insensitive collations

From ae5a234653a257313666f47ef235e9cb3ee92202 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Fri, 28 Dec 2018 09:46:31 +0100
Subject: [PATCH v2] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  11 +-
 doc/src/sgml/ref/create_collation.sgml        |  22 ++
 src/backend/access/hash/hashfunc.c            |  86 +++++
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  12 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/nodeAgg.c                |   4 +
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |   8 +
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 ++-
 src/backend/optimizer/util/tlist.c            |  25 ++
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  20 ++
 src/backend/utils/adt/varchar.c               |  20 ++
 src/backend/utils/adt/varlena.c               |  45 ++-
 src/backend/utils/cache/catcache.c            |   2 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 ++-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   3 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 331 +++++++++++++++++-
 .../regress/expected/collate.linux.utf8.out   |  25 +-
 src/test/regress/sql/collate.icu.utf8.sql     | 109 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   8 +
 54 files changed, 908 insertions(+), 109 deletions(-)

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index 3973ac75e8..0b05f9796d 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6b2b9e3742..7bd0d0aa2f 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index af4d0625ea..b087c1ec74 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..ec6343fa80 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,12 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index a0060a633d..456b55aa73 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,8 +244,50 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/*
 	 * Note: this is currently identical in behavior to hashvarlena, but keep
 	 * it as a separate function in case we someday want to do something
@@ -262,8 +306,50 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/* Same approach as hashtext */
 	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
 							   VARSIZE_ANY_EXHDR(key),
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index d4543b511e..2f47e775ef 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -47,6 +47,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -161,6 +162,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index 8fb51e8c3d..89dd371604 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 4f8a2a5bc2..2d974fe749 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3316,6 +3316,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3376,6 +3377,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3393,7 +3395,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index efe8c30383..01e85355b1 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -155,6 +156,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt, MemoryContext tempcxt,
 					bool use_variable_hash_iv)
@@ -174,6 +176,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -211,7 +214,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													parent);
 
 	MemoryContextSwitchTo(oldcontext);
@@ -374,8 +377,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 179a501f30..0387717180 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1217,6 +1217,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index daf56cd3d1..0dd2b02a9e 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -1283,6 +1283,7 @@ build_hash_table(AggState *aggstate)
 												 perhash->hashGrpColIdxHash,
 												 perhash->eqfuncoids,
 												 perhash->hashfunctions,
+												 perhash->aggnode->grpCollations,
 												 perhash->aggnode->numGroups,
 												 additionalsize,
 												 aggstate->hashcontext->ecxt_per_tuple_memory,
@@ -2376,6 +2377,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2387,6 +2389,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3141,6 +3144,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 58e0b10cd1..95b19be1ed 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index ba2f6686cf..3a86d9b964 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index c2c8beffc1..c44cfda51d 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 2d26cec831..8733c85afc 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 											 node->dupColIdx,
 											 rustate->eqfuncoids,
 											 rustate->hashfunctions,
+											 node->dupCollations,
 											 node->numGroups,
 											 0,
 											 rustate->tableContext,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 48b7aa9b8b..7b101ab946 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												node->dupColIdx,
 												setopstate->eqfuncoids,
 												setopstate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												setopstate->tableContext,
@@ -553,6 +554,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 84a1a91682..7f90b5f828 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -511,6 +511,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 										  node->keyColIdx,
 										  node->tab_eq_funcoids,
 										  node->tab_hash_funcs,
+										  node->tab_collations,
 										  nbuckets,
 										  0,
 										  node->hashtablecxt,
@@ -533,6 +534,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 											  node->keyColIdx,
 											  node->tab_eq_funcoids,
 											  node->tab_hash_funcs,
+											  node->tab_collations,
 											  nbuckets,
 											  0,
 											  node->hashtablecxt,
@@ -808,6 +810,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -906,6 +909,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -956,6 +960,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -992,6 +999,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index c5e4232e68..79cad1ca70 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 298e370745..6312ec451f 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index db49968409..201a19ea2e 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index be6b4ca2f4..5e832ef983 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index fa27f37d6f..6550b3dbed 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1672,6 +1672,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2138,6 +2139,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2157,6 +2159,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2179,9 +2182,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2207,6 +2212,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2285,6 +2291,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 91cf78233d..615236d121 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -256,14 +256,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1355,6 +1355,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1421,6 +1422,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1431,7 +1433,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1469,6 +1473,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1851,6 +1856,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1917,6 +1924,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2078,6 +2087,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2115,6 +2125,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2214,9 +2225,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2238,6 +2251,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2248,11 +2262,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2263,6 +2279,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2272,9 +2289,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5409,10 +5428,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5422,11 +5443,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6098,7 +6121,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6114,6 +6137,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6129,8 +6153,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6143,9 +6167,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6170,6 +6196,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6178,6 +6205,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6201,6 +6229,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6215,6 +6244,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6223,6 +6253,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6230,6 +6261,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6245,6 +6277,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6260,6 +6293,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6328,6 +6362,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6335,6 +6370,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6379,6 +6415,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6392,6 +6429,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6400,6 +6438,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6409,6 +6448,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 5500f33e63..00ba58bcbd 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -502,6 +502,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index eeaab2f4c9..c60a1bb509 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2657,7 +2657,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2678,7 +2678,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 35c87535d3..2abe119529 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2157,6 +2157,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2177,7 +2178,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index ce1ded888f..6a31ed7852 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3954,7 +3954,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index eb35188e06..c61856b86a 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 1b21da8d09..9b1c5bd7ff 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index a3dc3be5a8..998f34c94a 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index cdda860e73..3fa07fab3d 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -777,6 +777,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -785,6 +787,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -917,6 +921,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -925,6 +931,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1068,6 +1076,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1079,6 +1089,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1256,6 +1268,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1267,6 +1281,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1443,6 +1459,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1454,6 +1472,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index d5a5800cb2..13f48793b7 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -933,10 +933,20 @@ Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		elog(ERROR, "TODO");
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
@@ -952,10 +962,20 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		elog(ERROR, "TODO");
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 50a157df9f..c74b961635 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1430,7 +1430,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * equal strings in the input - then we win big by avoiding expensive
 		 * collation-aware comparisons.
 		 */
-		if (len1 == len2 && memcmp(arg1, arg2, len1) == 0)
+		if ((!mylocale || (mylocale && mylocale->deterministic)) &&
+			len1 == len2 && memcmp(arg1, arg2, len1) == 0)
 			return 0;
 
 #ifdef WIN32
@@ -1508,7 +1509,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 			 * reasons, so we follow Perl's lead and sort "equal" strings
 			 * according to strcmp (on the UTF-8 representation).
 			 */
-			if (result == 0)
+			if (result == 0 &&
+				(!mylocale || (mylocale && mylocale->deterministic)))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1599,7 +1601,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * so we follow Perl's lead and sort "equal" strings according to
 		 * strcmp().
 		 */
-		if (result == 0)
+		if (result == 0 &&
+			(!mylocale || (mylocale && mylocale->deterministic)))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1643,6 +1646,23 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
+	if (PG_GET_COLLATION() &&
+		PG_GET_COLLATION() != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(PG_GET_COLLATION())->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) == 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1673,11 +1693,29 @@ texteq(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
 textne(PG_FUNCTION_ARGS)
 {
+	if (PG_GET_COLLATION() &&
+		PG_GET_COLLATION() != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(PG_GET_COLLATION())->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) != 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1702,6 +1740,7 @@ textne(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 4176ced923..c4d76b8dac 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -188,7 +188,7 @@ texteqfast(Datum a, Datum b)
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 33b5b1649c..1b1691117f 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 017c11bc94..613e60e6a3 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1766,8 +1766,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 341b1a51f2..70c2b00831 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13259,6 +13259,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13276,28 +13277,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13324,6 +13332,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 0a181b01d9..1540df5c82 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 51f9b2a2ca..9be977b2c6 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 92a10ebd5c..21ef0140d4 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -110,6 +110,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -120,6 +121,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -246,6 +248,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index a9f9872a78..000277a343 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 8d700c06c5..f2444c85c6 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 5ed0f40f69..b9ad9a8061 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -689,6 +689,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -858,6 +859,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1870,6 +1872,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index f116bc23ff..e10daaf500 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -772,6 +773,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -796,6 +798,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -814,9 +817,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -838,6 +843,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -912,6 +918,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index ec1ea10233..dd0cca98fe 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -63,7 +63,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 9fa52e1278..f3556fe268 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -48,6 +48,7 @@ extern SortGroupClause *get_sortgroupref_clause_noerr(Index sortref,
 							  List *clauses);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index 36fb584e23..9a271b09e9 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 6408993001..5675aa15f6 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 88a3134862..ca775a3681 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f485b5c330..a0e7e4517f 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,27 +1100,320 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ ABC |          1 |    1
+ abc |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+INSERT INTO test22 VALUES (1, 'abc');
+INSERT INTO test22 VALUES (2, 'ABC');
+SELECT * FROM test22_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
 RESET search_path;
 -- leave a collation for pg_upgrade test
 CREATE COLLATION coll_icu_upgrade FROM "und-x-icu";
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index 400a747cdc..9c5b8abef8 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,24 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index ef39445b30..9b62d6b1ad 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,7 +425,116 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+INSERT INTO test22 VALUES (1, 'abc');
+INSERT INTO test22 VALUES (2, 'ABC');
+SELECT * FROM test22_1;
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
 RESET search_path;
 
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index b51162e3a1..3a3ece9c62 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,5 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;

base-commit: ae4472c619341ff0517254d395d74796277622e6
-- 
2.20.1

From dcd081ba5fdc3a29adddcd52deac5fb67d18fcc1 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 15 Jan 2019 15:54:33 +0100
Subject: [PATCH v3] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  11 +-
 doc/src/sgml/ref/create_collation.sgml        |  22 ++
 src/backend/access/hash/hashfunc.c            |  86 +++++
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  12 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/nodeAgg.c                |   4 +
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |   8 +
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 ++-
 src/backend/optimizer/util/tlist.c            |  25 ++
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  20 +
 src/backend/utils/adt/varchar.c               |  20 +
 src/backend/utils/adt/varlena.c               |  51 ++-
 src/backend/utils/cache/catcache.c            |   2 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   3 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 341 +++++++++++++++++-
 .../regress/expected/collate.linux.utf8.out   |  25 +-
 src/test/regress/sql/collate.icu.utf8.sql     | 115 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   8 +
 54 files changed, 928 insertions(+), 111 deletions(-)

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index 24200fb5fa..c4672f6853 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index af4d0625ea..b087c1ec74 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..ec6343fa80 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,12 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..144dd114a1 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,8 +244,50 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/*
 	 * Note: this is currently identical in behavior to hashvarlena, but keep
 	 * it as a separate function in case we someday want to do something
@@ -262,8 +306,50 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/* Same approach as hashtext */
 	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
 							   VARSIZE_ANY_EXHDR(key),
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 467ab5a5e5..e7529ac1e8 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -47,6 +47,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -161,6 +162,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index e6a5c3a555..c33ab76f99 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 4047d24b03..4eada12e70 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3316,6 +3316,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3376,6 +3377,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3393,7 +3395,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index 4e7600e4ed..cef6323c63 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -155,6 +156,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt, MemoryContext tempcxt,
 					bool use_variable_hash_iv)
@@ -174,6 +176,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -211,7 +214,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													parent);
 
 	MemoryContextSwitchTo(oldcontext);
@@ -374,8 +377,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 7415dfa45e..f83b5787fe 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1218,6 +1218,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 508c919574..1783216e63 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -1283,6 +1283,7 @@ build_hash_table(AggState *aggstate)
 												 perhash->hashGrpColIdxHash,
 												 perhash->eqfuncoids,
 												 perhash->hashfunctions,
+												 perhash->aggnode->grpCollations,
 												 perhash->aggnode->numGroups,
 												 additionalsize,
 												 aggstate->hashcontext->ecxt_per_tuple_memory,
@@ -2376,6 +2377,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2387,6 +2389,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3141,6 +3144,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index d2488ad988..bef2c7fbdc 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 											 node->dupColIdx,
 											 rustate->eqfuncoids,
 											 rustate->hashfunctions,
+											 node->dupCollations,
 											 node->numGroups,
 											 0,
 											 rustate->tableContext,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 5d8c8b8b02..5a86bbcc95 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												node->dupColIdx,
 												setopstate->eqfuncoids,
 												setopstate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												setopstate->tableContext,
@@ -553,6 +554,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 574e7bc4fa..1e7db81c7f 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -511,6 +511,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 										  node->keyColIdx,
 										  node->tab_eq_funcoids,
 										  node->tab_hash_funcs,
+										  node->tab_collations,
 										  nbuckets,
 										  0,
 										  node->hashtablecxt,
@@ -533,6 +534,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 											  node->keyColIdx,
 											  node->tab_eq_funcoids,
 											  node->tab_hash_funcs,
+											  node->tab_collations,
 											  nbuckets,
 											  0,
 											  node->hashtablecxt,
@@ -808,6 +810,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -906,6 +909,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -956,6 +960,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -992,6 +999,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 7ae56074ca..4942003e82 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 006a3d1772..63dc0dacf9 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 0fde876c77..0af43aeb47 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index ec6f2569ab..7e40c2990b 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1672,6 +1672,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2138,6 +2139,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2157,6 +2159,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2179,9 +2182,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2207,6 +2212,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2285,6 +2291,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 97d0c28132..61e9dc5938 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -253,14 +253,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1352,6 +1352,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1418,6 +1419,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1428,7 +1430,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1466,6 +1470,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1848,6 +1853,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1914,6 +1921,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2075,6 +2084,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2112,6 +2122,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2211,9 +2222,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2235,6 +2248,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2245,11 +2259,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2260,6 +2276,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2269,9 +2286,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5292,10 +5311,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5305,11 +5326,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -5981,7 +6004,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -5997,6 +6020,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6012,8 +6036,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6026,9 +6050,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6053,6 +6079,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6061,6 +6088,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6084,6 +6112,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6098,6 +6127,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6106,6 +6136,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6113,6 +6144,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6128,6 +6160,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6143,6 +6176,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6211,6 +6245,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6218,6 +6253,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6262,6 +6298,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6275,6 +6312,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6283,6 +6321,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6292,6 +6331,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index d0cc14f11d..a673819890 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -502,6 +502,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index 60993c3a7a..7898f4a043 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2658,7 +2658,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2679,7 +2679,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 901433c68c..ee2cce452e 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2158,6 +2158,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2178,7 +2179,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index e457d81f23..f6567075ba 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3954,7 +3954,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 6075bc3db7..0165b23a6e 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e606eb342f..d1c6a0100d 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -778,6 +778,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -786,6 +788,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -918,6 +922,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -926,6 +932,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1069,6 +1077,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1080,6 +1090,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1257,6 +1269,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1268,6 +1282,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1444,6 +1460,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1455,6 +1473,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 5cf927e27f..b50f441c8f 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -933,10 +933,20 @@ Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		elog(ERROR, "TODO");
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
@@ -952,10 +962,20 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		elog(ERROR, "TODO");
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 801d8c5c29..66b0e5fe99 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1430,7 +1430,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * equal strings in the input - then we win big by avoiding expensive
 		 * collation-aware comparisons.
 		 */
-		if (len1 == len2 && memcmp(arg1, arg2, len1) == 0)
+		if ((!mylocale || (mylocale && mylocale->deterministic)) &&
+			len1 == len2 && memcmp(arg1, arg2, len1) == 0)
 			return 0;
 
 #ifdef WIN32
@@ -1508,7 +1509,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 			 * reasons, so we follow Perl's lead and sort "equal" strings
 			 * according to strcmp (on the UTF-8 representation).
 			 */
-			if (result == 0)
+			if (result == 0 &&
+				(!mylocale || (mylocale && mylocale->deterministic)))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1599,7 +1601,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * so we follow Perl's lead and sort "equal" strings according to
 		 * strcmp().
 		 */
-		if (result == 0)
+		if (result == 0 &&
+			(!mylocale || (mylocale && mylocale->deterministic)))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1643,6 +1646,23 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
+	if (PG_GET_COLLATION() &&
+		PG_GET_COLLATION() != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(PG_GET_COLLATION())->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) == 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1673,11 +1693,29 @@ texteq(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
 textne(PG_FUNCTION_ARGS)
 {
+	if (PG_GET_COLLATION() &&
+		PG_GET_COLLATION() != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(PG_GET_COLLATION())->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, PG_GET_COLLATION()) != 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1702,6 +1740,7 @@ textne(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
@@ -2142,7 +2181,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	bool		arg1_match;
 
 	/* Fast pre-check for equality, as discussed in varstr_cmp() */
-	if (len1 == len2 && memcmp(a1p, a2p, len1) == 0)
+	if ((!sss->locale || (sss->locale && sss->locale->deterministic)) &&
+		len1 == len2 && memcmp(a1p, a2p, len1) == 0)
 	{
 		/*
 		 * No change in buf1 or buf2 contents, so avoid changing last_len1 or
@@ -2277,7 +2317,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	 * equal. Believing that would be bad news for a number of reasons, so we
 	 * follow Perl's lead and sort "equal" strings according to strcmp().
 	 */
-	if (result == 0)
+	if (result == 0 &&
+		(!sss->locale || (sss->locale && sss->locale->deterministic)))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 8152f7e21e..2097e20945 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -188,7 +188,7 @@ texteqfast(Datum a, Datum b)
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index fba0ee8b84..f3bbaed992 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index e55ba668ce..7df4e85e2f 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 0e129f9654..9ff35fd31e 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13259,6 +13259,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13276,28 +13277,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13324,6 +13332,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4da6719ce7..b43300c262 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 3831cceedf..76cc5caa61 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -247,6 +249,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 7cae085177..9c512bddf9 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -688,6 +688,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -857,6 +858,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1869,6 +1871,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..840ba416a0 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index bec0c38617..8e8f570e00 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -63,7 +63,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 8b967f9583..70f8454a44 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -48,6 +48,7 @@ extern SortGroupClause *get_sortgroupref_clause_noerr(Index sortref,
 							  List *clauses);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index ceec85db92..f622b9e512 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f485b5c330..02699ae102 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,27 +1100,330 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+INSERT INTO test22 VALUES (1, 'abc');
+INSERT INTO test22 VALUES (2, 'ABC');
+SELECT * FROM test22_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
 RESET search_path;
 -- leave a collation for pg_upgrade test
 CREATE COLLATION coll_icu_upgrade FROM "und-x-icu";
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index 400a747cdc..9c5b8abef8 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,24 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index ef39445b30..c0a5cf776d 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,7 +425,122 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+INSERT INTO test22 VALUES (1, 'abc');
+INSERT INTO test22 VALUES (2, 'ABC');
+SELECT * FROM test22_1;
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
 RESET search_path;
 
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index b51162e3a1..3a3ece9c62 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,5 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;

base-commit: 0944ec54de389b4b8a471ca1f40f1b9d81de1f30
-- 
2.20.1

From 1d675c51fb40a23b355ad5aa3de382e9fd4ffc82 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Fri, 25 Jan 2019 16:13:00 +0100
Subject: [PATCH v4] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  11 +-
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            |  86 +++
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  12 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  39 +-
 src/backend/utils/adt/varchar.c               | 117 +++
 src/backend/utils/adt/varlena.c               | 166 +++--
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   3 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 702 +++++++++++++++++-
 .../regress/expected/collate.linux.utf8.out   |  25 +-
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 230 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   8 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      |  98 +++
 64 files changed, 1793 insertions(+), 170 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index 24200fb5fa..c4672f6853 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index af4d0625ea..b087c1ec74 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..ec6343fa80 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,12 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 4930ec17f6..ee84e60ca6 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3962,6 +3962,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..a2ac1f8137 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,8 +244,50 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/*
 	 * Note: this is currently identical in behavior to hashvarlena, but keep
 	 * it as a separate function in case we someday want to do something
@@ -262,8 +306,50 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	/* Same approach as hashtext */
 	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
 							   VARSIZE_ANY_EXHDR(key),
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 4047d24b03..4eada12e70 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3316,6 +3316,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3376,6 +3377,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3393,7 +3395,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index 4e7600e4ed..cef6323c63 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -155,6 +156,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt, MemoryContext tempcxt,
 					bool use_variable_hash_iv)
@@ -174,6 +176,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -211,7 +214,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													parent);
 
 	MemoryContextSwitchTo(oldcontext);
@@ -374,8 +377,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 2a7bc01563..0341250f1d 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1218,6 +1218,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 589573b879..d9d5a7b78b 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -95,6 +95,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -261,7 +263,8 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										values[attrnum],
 										slot->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 508c919574..1e0b46cd95 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -747,15 +747,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1283,6 +1282,7 @@ build_hash_table(AggState *aggstate)
 												 perhash->hashGrpColIdxHash,
 												 perhash->eqfuncoids,
 												 perhash->hashfunctions,
+												 perhash->aggnode->grpCollations,
 												 perhash->aggnode->numGroups,
 												 additionalsize,
 												 aggstate->hashcontext->ecxt_per_tuple_memory,
@@ -2376,6 +2376,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2387,6 +2388,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3141,6 +3143,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index d2488ad988..bef2c7fbdc 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 											 node->dupColIdx,
 											 rustate->eqfuncoids,
 											 rustate->hashfunctions,
+											 node->dupCollations,
 											 node->numGroups,
 											 0,
 											 rustate->tableContext,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 5d8c8b8b02..5a86bbcc95 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												node->dupColIdx,
 												setopstate->eqfuncoids,
 												setopstate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												setopstate->tableContext,
@@ -553,6 +554,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 574e7bc4fa..6d2a66ec67 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -511,6 +511,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 										  node->keyColIdx,
 										  node->tab_eq_funcoids,
 										  node->tab_hash_funcs,
+										  node->tab_collations,
 										  nbuckets,
 										  0,
 										  node->hashtablecxt,
@@ -533,6 +534,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 											  node->keyColIdx,
 											  node->tab_eq_funcoids,
 											  node->tab_hash_funcs,
+											  node->tab_collations,
 											  nbuckets,
 											  0,
 											  node->hashtablecxt,
@@ -633,6 +635,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -670,8 +673,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -713,6 +716,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -808,6 +812,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -906,6 +911,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -956,6 +962,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -992,6 +1001,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 7ae56074ca..4942003e82 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 3eb7e95d64..8296da047c 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 0fde876c77..0af43aeb47 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index ec6f2569ab..7e40c2990b 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1672,6 +1672,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2138,6 +2139,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2157,6 +2159,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2179,9 +2182,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2207,6 +2212,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2285,6 +2291,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 97d0c28132..61e9dc5938 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -253,14 +253,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1352,6 +1352,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1418,6 +1419,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1428,7 +1430,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1466,6 +1470,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1848,6 +1853,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1914,6 +1921,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2075,6 +2084,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2112,6 +2122,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2211,9 +2222,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2235,6 +2248,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2245,11 +2259,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2260,6 +2276,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2269,9 +2286,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5292,10 +5311,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5305,11 +5326,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -5981,7 +6004,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -5997,6 +6020,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6012,8 +6036,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6026,9 +6050,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6053,6 +6079,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6061,6 +6088,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6084,6 +6112,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6098,6 +6127,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6106,6 +6136,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6113,6 +6144,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6128,6 +6160,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6143,6 +6176,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6211,6 +6245,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6218,6 +6253,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6262,6 +6298,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6275,6 +6312,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6283,6 +6321,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6292,6 +6331,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index d0cc14f11d..a673819890 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -502,6 +502,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index f21c9b32a6..22d5d7e7a8 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2658,7 +2658,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2679,7 +2679,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 901433c68c..ee2cce452e 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2158,6 +2158,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2178,7 +2179,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index e457d81f23..f6567075ba 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3954,7 +3954,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 46c4fc727c..43060e5288 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(char *t, int tlen, char *p, int plen,
 static int SB_IMatchText(char *t, int tlen, char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(char *s, int slen, char *p, int plen);
+static int	GenericMatchText(char *s, int slen, char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(char *s, int slen, char *p, int plen)
+GenericMatchText(char *s, int slen, char *p, int plen, Oid collation)
 {
+	if (collation)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 6075bc3db7..0165b23a6e 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e1aa3d0044..55488f1192 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -778,6 +778,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -786,6 +788,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -918,6 +922,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -926,6 +932,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1069,6 +1077,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1080,6 +1090,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1257,6 +1269,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1268,6 +1282,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1444,6 +1460,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1455,6 +1473,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -2901,11 +2921,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
-	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
+	 */
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /* ----------
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 5cf927e27f..d43fbe9a03 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -23,6 +23,7 @@
 #include "nodes/nodeFuncs.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -708,6 +709,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -716,10 +733,19 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
+	if (collid != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(collid)->deterministic)
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	else
+	{
 	/*
 	 * Since we only care about equality or not-equality, we can avoid all the
 	 * expense of strcoll() here, and just do bitwise comparison.
@@ -728,6 +754,7 @@ bpchareq(PG_FUNCTION_ARGS)
 		result = false;
 	else
 		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -743,10 +770,17 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
+	if (collid != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(collid)->deterministic)
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	else
+	{
 	/*
 	 * Since we only care about equality or not-equality, we can avoid all the
 	 * expense of strcoll() here, and just do bitwise comparison.
@@ -755,6 +789,7 @@ bpcharne(PG_FUNCTION_ARGS)
 		result = true;
 	else
 		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -933,13 +968,53 @@ Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any(buf, bsize);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	result = hash_any((unsigned char *) keydata, keylen);
 
 	/* Avoid leaking memory for toasted inputs */
@@ -952,13 +1027,55 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
+	if (collid != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t	mylocale = pg_newlocale_from_collation(collid);
+
+		if (mylocale && !mylocale->deterministic)
+		{
+			if (mylocale->provider == COLLPROVIDER_ICU)
+			{
+#ifdef USE_ICU
+				int32_t		ulen = -1;
+				UChar	   *uchar = NULL;
+				Size		bsize;
+				uint8_t	   *buf;
+
+				ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+				bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+										uchar, ulen, NULL, 0);
+				buf = palloc(bsize);
+				ucol_getSortKey(mylocale->info.icu.ucol,
+								uchar, ulen, buf, bsize);
+
+				result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+				PG_FREE_IF_COPY(key, 0);
+
+				return result;
+#else
+				/* shouldn't happen */
+				elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+#endif
+			}
+		}
+	}
+
 	result = hash_any_extended((unsigned char *) keydata, keylen,
 							   PG_GETARG_INT64(1));
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 801d8c5c29..5bd65e422f 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -1373,6 +1373,22 @@ text_position_cleanup(TextPositionState *state)
 	}
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1385,6 +1401,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1406,20 +1424,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1430,7 +1435,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * equal strings in the input - then we win big by avoiding expensive
 		 * collation-aware comparisons.
 		 */
-		if (len1 == len2 && memcmp(arg1, arg2, len1) == 0)
+		if ((!mylocale || (mylocale && mylocale->deterministic)) &&
+			len1 == len2 && memcmp(arg1, arg2, len1) == 0)
 			return 0;
 
 #ifdef WIN32
@@ -1508,7 +1514,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 			 * reasons, so we follow Perl's lead and sort "equal" strings
 			 * according to strcmp (on the UTF-8 representation).
 			 */
-			if (result == 0)
+			if (result == 0 &&
+				(!mylocale || (mylocale && mylocale->deterministic)))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1599,7 +1606,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * so we follow Perl's lead and sort "equal" strings according to
 		 * strcmp().
 		 */
-		if (result == 0)
+		if (result == 0 &&
+			(!mylocale || (mylocale && mylocale->deterministic)))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1643,6 +1651,26 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(collid)->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, collid) == 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1673,11 +1701,32 @@ texteq(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
 textne(PG_FUNCTION_ARGS)
 {
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID &&
+		!pg_newlocale_from_collation(collid)->deterministic)
+	{
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
+		bool		result;
+
+		result = (text_cmp(arg1, arg2, collid) != 0);
+
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
+
+		PG_RETURN_BOOL(result);
+	}
+	else
+	{
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
 	bool		result;
@@ -1702,6 +1751,7 @@ textne(PG_FUNCTION_ARGS)
 	}
 
 	PG_RETURN_BOOL(result);
+	}
 }
 
 Datum
@@ -1842,6 +1892,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1878,20 +1930,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2142,7 +2181,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	bool		arg1_match;
 
 	/* Fast pre-check for equality, as discussed in varstr_cmp() */
-	if (len1 == len2 && memcmp(a1p, a2p, len1) == 0)
+	if ((!sss->locale || (sss->locale && sss->locale->deterministic)) &&
+		len1 == len2 && memcmp(a1p, a2p, len1) == 0)
 	{
 		/*
 		 * No change in buf1 or buf2 contents, so avoid changing last_len1 or
@@ -2277,7 +2317,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	 * equal. Believing that would be bad news for a number of reasons, so we
 	 * follow Perl's lead and sort "equal" strings according to strcmp().
 	 */
-	if (result == 0)
+	if (result == 0 &&
+		(!sss->locale || (sss->locale && sss->locale->deterministic)))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2704,10 +2745,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2721,10 +2770,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2738,10 +2795,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2755,10 +2820,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -4494,11 +4567,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4604,7 +4678,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			text_position_cleanup(&state);
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4639,7 +4713,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4684,7 +4758,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 258a1d64cc..85dc0fbf8c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -181,13 +181,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index fba0ee8b84..f3bbaed992 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 2b1a94733b..4be0c42175 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13259,6 +13259,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13276,28 +13277,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13324,6 +13332,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4da6719ce7..b43300c262 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 3831cceedf..76cc5caa61 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -247,6 +249,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 64e8ef3740..73fa8b78be 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -688,6 +688,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -857,6 +858,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1869,6 +1871,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..840ba416a0 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index bec0c38617..8e8f570e00 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -63,7 +63,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 8b967f9583..70f8454a44 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -48,6 +48,7 @@ extern SortGroupClause *get_sortgroupref_clause_noerr(Index sortref,
 							  List *clauses);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index ceec85db92..f622b9e512 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f485b5c330..eaf58637f8 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,27 +1100,691 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs;
+  x  
+-----
+ ABC
+ ghi
+ abc
+ def
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {NULL,DEF,GHI}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {NULL,DEF,GHI}
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test22_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test23_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test32_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test33_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
 RESET search_path;
 -- leave a collation for pg_upgrade test
 CREATE COLLATION coll_icu_upgrade FROM "und-x-icu";
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index 400a747cdc..9c5b8abef8 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,24 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
-NOTICE:  drop cascades to 18 other objects
-DETAIL:  drop cascades to table collate_test1
-drop cascades to table collate_test_like
-drop cascades to table collate_test2
-drop cascades to table collate_test3
-drop cascades to type testdomain_sv
-drop cascades to table collate_test4
-drop cascades to table collate_test5
-drop cascades to table collate_test10
-drop cascades to table collate_test6
-drop cascades to view collview1
-drop cascades to view collview2
-drop cascades to view collview3
-drop cascades to type testdomain
-drop cascades to function mylt(text,text)
-drop cascades to function mylt_noninline(text,text)
-drop cascades to function mylt_plpgsql(text,text)
-drop cascades to function mylt2(text,text)
-drop cascades to function dup(anyelement)
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index 588d069589..043d9fa532 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index ef39445b30..cb0f221982 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,7 +425,237 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+SELECT * FROM test22_1;
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+SELECT * FROM test23_1;
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+SELECT * FROM test32_1;
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+SELECT * FROM test33_1;
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
 RESET search_path;
 
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index b51162e3a1..3a3ece9c62 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,5 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
+SET client_min_messages TO 'warning';
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 843f511b3d..82d5a7edcd 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..f9edda6ab6
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,98 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false)");
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text PRIMARY KEY, b text)");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text COLLATE case_insensitive PRIMARY KEY, b text)");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text, b text)");
+$node_publisher->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text COLLATE case_insensitive, b text)");
+$node_subscriber->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	"CREATE PUBLICATION pub1 FOR ALL TABLES");
+
+$node_subscriber->safe_psql('postgres',
+	"CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr application_name=sub1' PUBLICATION pub1 WITH (copy_data = false)");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab1 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# Note: Even though the UPDATE command above only updates column "b",
+# the replication target will also update column "a", because the
+# whole row is shippped.
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab1 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive primary key');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab2 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab2 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive column with replica identity full');

base-commit: 7c079d7417a8f2d4bf5144732e2f85117db9214f
-- 
2.20.1

From 60bb8dc01f919268b13a90855cada3d820ad6716 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 6 Feb 2019 23:32:32 +0100
Subject: [PATCH v5] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Discussion: https://www.postgresql.org/message-id/flat/1ccc668f-4cbc-0bef-af67-450b47cdfee7@2ndquadrant.com/
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  61 +-
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            | 100 ++-
 src/backend/access/spgist/spgtextproc.c       |   3 +-
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/commands/extension.c              |   6 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  12 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  39 +-
 src/backend/utils/adt/varchar.c               | 159 +++-
 src/backend/utils/adt/varlena.c               | 288 ++++---
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   3 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 708 ++++++++++++++++++
 .../regress/expected/collate.linux.utf8.out   |   5 +
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 239 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   7 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      |  98 +++
 66 files changed, 1970 insertions(+), 224 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index d641361aef..7c18eaa508 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index af4d0625ea..b087c1ec74 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..35cb167326 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,13 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>;
+    see <xref linkend="collation-nondeterministic"/>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
@@ -883,6 +885,55 @@ <title>Copying Collations</title>
    </para>
    </sect4>
    </sect3>
+
+   <sect3 id="collation-nondeterministic">
+    <title>Nondeterminstic Collations</title>
+
+    <para>
+     A collation is either <firstterm>deterministic</firstterm> or
+     <firstterm>nondeterministic</firstterm>.  A deterministic collation uses
+     deterministic comparisons, which means that it considers strings to be
+     equal only if they consist of the same byte sequence.  Nondetermistic
+     comparison may determine strings to be equal even if they consist of
+     different bytes.  Typical situations include case-insensitive comparison,
+     accent-insensitive comparison, as well as comparion of strings in
+     different Unicode normal forms.  It is up to the collation provider to
+     actually implement such insensitive comparisons; the deterministic flag
+     only determines whether ties are to be broken using bytewise comparison.
+     See also <ulink url="https://unicode.org/reports/tr10">Unicode Technical
+     Standard 10</ulink> for more information on the terminology.
+    </para>
+
+    <para>
+     To create a nondeterministic collation, specify the property
+     <literal>deterministic = false</literal> to <command>CREATE
+     COLLATION</command>, for example:
+<programlisting>
+CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
+</programlisting>
+     This example would use the standard Unicode collation in a
+     nondeterministic way.  In particular, this would allow strings in
+     different normal forms to be compared correctly.  More interesting
+     examples make use of the ICU customization facilities explained above.
+     For example:
+<programlisting>
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+</programlisting>
+    </para>
+
+    <para>
+     All standard and predefined collations are deterministic, all
+     user-defined collations are deterministic by default.  While
+     nondeterministic collations give a more <quote>correct</quote> behavior,
+     especially when considering the full power of Unicode and its many
+     special cases, they also have some drawbacks.  Foremost, their use leads
+     to a performance penalty.  Also, certain operations are not possible with
+     nondeterministic collations, such as pattern matching operations.
+     Therefore, they should be used only in cases where they are specifically
+     wanted.
+    </para>
+   </sect3>
   </sect2>
  </sect1>
 
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 4930ec17f6..ee84e60ca6 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3962,6 +3962,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..785e02a5fe 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,15 +244,51 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/*
-	 * Note: this is currently identical in behavior to hashvarlena, but keep
-	 * it as a separate function in case we someday want to do something
-	 * different in non-C locales.  (See also hashbpchar, if so.)
-	 */
-	result = hash_any((unsigned char *) VARDATA_ANY(key),
-					  VARSIZE_ANY_EXHDR(key));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -262,12 +300,52 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/* Same approach as hashtext */
-	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
-							   VARSIZE_ANY_EXHDR(key),
-							   PG_GETARG_INT64(1));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 39cd391529..d22998c54b 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -630,7 +630,8 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
 			 * query (prefix) string, so we don't need to check it again.
 			 */
 			res = (level >= queryLen) ||
-				DatumGetBool(DirectFunctionCall2(text_starts_with,
+				DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
+													 PG_GET_COLLATION(),
 												 out->leafValue,
 												 PointerGetDatum(query)));
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..d4723fced8 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -901,7 +901,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		{
 			const char *qSchemaName = quote_identifier(schemaName);
 
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("@extschema@"),
 										CStringGetTextDatum(qSchemaName));
@@ -913,7 +914,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		 */
 		if (control->module_pathname)
 		{
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("MODULE_PATHNAME"),
 										CStringGetTextDatum(control->module_pathname));
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index db3777d15e..bc3e05cd1b 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3327,6 +3327,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3387,6 +3388,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3404,7 +3406,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index 4e7600e4ed..cef6323c63 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -155,6 +156,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt, MemoryContext tempcxt,
 					bool use_variable_hash_iv)
@@ -174,6 +176,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -211,7 +214,7 @@ BuildTupleHashTable(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													parent);
 
 	MemoryContextSwitchTo(oldcontext);
@@ -374,8 +377,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 2a7bc01563..0341250f1d 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1218,6 +1218,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 589573b879..d9d5a7b78b 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -95,6 +95,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -261,7 +263,8 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										values[attrnum],
 										slot->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 263a0f8127..060a34e746 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -746,15 +746,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1284,6 +1283,7 @@ build_hash_table(AggState *aggstate)
 												 perhash->hashGrpColIdxHash,
 												 perhash->eqfuncoids,
 												 perhash->hashfunctions,
+												 perhash->aggnode->grpCollations,
 												 perhash->aggnode->numGroups,
 												 additionalsize,
 												 aggstate->hashcontext->ecxt_per_tuple_memory,
@@ -2377,6 +2377,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2388,6 +2389,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3151,6 +3153,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index d2488ad988..bef2c7fbdc 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 											 node->dupColIdx,
 											 rustate->eqfuncoids,
 											 rustate->hashfunctions,
+											 node->dupCollations,
 											 node->numGroups,
 											 0,
 											 rustate->tableContext,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 5d8c8b8b02..5a86bbcc95 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												node->dupColIdx,
 												setopstate->eqfuncoids,
 												setopstate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												setopstate->tableContext,
@@ -553,6 +554,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 152696035c..c5aa08044e 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -511,6 +511,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 										  node->keyColIdx,
 										  node->tab_eq_funcoids,
 										  node->tab_hash_funcs,
+										  node->tab_collations,
 										  nbuckets,
 										  0,
 										  node->hashtablecxt,
@@ -533,6 +534,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 											  node->keyColIdx,
 											  node->tab_eq_funcoids,
 											  node->tab_hash_funcs,
+											  node->tab_collations,
 											  nbuckets,
 											  0,
 											  node->hashtablecxt,
@@ -633,6 +635,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -670,8 +673,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -713,6 +716,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -808,6 +812,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -906,6 +911,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -956,6 +962,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -992,6 +1001,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 157ac042b8..b090828c01 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index b44ead269f..cb7b7ae798 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index f97cf37f1f..ae92b48200 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 3b002778ad..04b2514a7b 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1675,6 +1675,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2141,6 +2142,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2160,6 +2162,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2182,9 +2185,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2210,6 +2215,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2288,6 +2294,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 1b4f7db649..082496a349 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -255,14 +255,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1382,6 +1382,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1448,6 +1449,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1458,7 +1460,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1496,6 +1500,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1878,6 +1883,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1944,6 +1951,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2105,6 +2114,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2142,6 +2152,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2241,9 +2252,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2265,6 +2278,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2275,11 +2289,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2290,6 +2306,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2299,9 +2316,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5360,10 +5379,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5373,11 +5394,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6049,7 +6072,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6065,6 +6088,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6080,8 +6104,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6094,9 +6118,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6121,6 +6147,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6129,6 +6156,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6152,6 +6180,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6166,6 +6195,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6174,6 +6204,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6181,6 +6212,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6196,6 +6228,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6211,6 +6244,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6279,6 +6313,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6286,6 +6321,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6330,6 +6366,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6343,6 +6380,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6351,6 +6389,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6360,6 +6399,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 14d1c67a94..bb3b7969f2 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -503,6 +503,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index d478ae7e19..c62450f78d 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2657,7 +2657,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2678,7 +2678,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 8c9721935d..bc1f00d33e 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2154,6 +2154,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2174,7 +2175,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index a785361fd0..331c1766bf 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3954,7 +3954,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(*locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 46c4fc727c..43060e5288 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(char *t, int tlen, char *p, int plen,
 static int SB_IMatchText(char *t, int tlen, char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(char *s, int slen, char *p, int plen);
+static int	GenericMatchText(char *s, int slen, char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(char *s, int slen, char *p, int plen)
+GenericMatchText(char *s, int slen, char *p, int plen, Oid collation)
 {
+	if (collation)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 2d384a9944..4db2d0d0e1 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e1aa3d0044..55488f1192 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -778,6 +778,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -786,6 +788,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -918,6 +922,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -926,6 +932,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1069,6 +1077,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1080,6 +1090,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1257,6 +1269,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1268,6 +1282,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1444,6 +1460,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1455,6 +1473,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -2901,11 +2921,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
-	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
+	 */
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /* ----------
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 5cf927e27f..c2316415a9 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -23,6 +23,7 @@
 #include "nodes/nodeFuncs.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -708,6 +709,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -716,18 +733,30 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = false;
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = false;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -743,18 +772,28 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = true;
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = true;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -924,23 +963,60 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 /*
  * bpchar needs a specialized hash function because we want to ignore
  * trailing blanks in comparisons.
- *
- * Note: currently there is no need for locale-specific behavior here,
- * but if we ever change the semantics of bpchar comparison to trust
- * strcoll() completely, we'd need to do something different in non-C locales.
  */
 Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any((unsigned char *) keydata, keylen);
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) keydata, keylen);
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -952,15 +1028,56 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any_extended((unsigned char *) keydata, keylen,
-							   PG_GETARG_INT64(1));
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) keydata, keylen,
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 693ccc5149..b94b15eea2 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -122,13 +122,14 @@ static text *text_substring(Datum str,
 			   int32 length,
 			   bool length_not_specified);
 static text *text_overlay(text *t1, text *t2, int sp, int sl);
-static int	text_position(text *t1, text *t2);
-static void text_position_setup(text *t1, text *t2, TextPositionState *state);
+static int	text_position(text *t1, text *t2, Oid collid);
+static void text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state);
 static bool text_position_next(TextPositionState *state);
 static char *text_position_next_internal(char *start_ptr, TextPositionState *state);
 static char *text_position_get_match_ptr(TextPositionState *state);
 static int	text_position_get_match_pos(TextPositionState *state);
 static void text_position_cleanup(TextPositionState *state);
+static void check_collation_set(Oid collid);
 static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static bytea *bytea_catenate(bytea *t1, bytea *t2);
 static bytea *bytea_substring(Datum str,
@@ -1094,7 +1095,7 @@ textpos(PG_FUNCTION_ARGS)
 	text	   *str = PG_GETARG_TEXT_PP(0);
 	text	   *search_str = PG_GETARG_TEXT_PP(1);
 
-	PG_RETURN_INT32((int32) text_position(str, search_str));
+	PG_RETURN_INT32((int32) text_position(str, search_str, PG_GET_COLLATION()));
 }
 
 /*
@@ -1112,7 +1113,7 @@ textpos(PG_FUNCTION_ARGS)
  *	functions.
  */
 static int
-text_position(text *t1, text *t2)
+text_position(text *t1, text *t2, Oid collid)
 {
 	TextPositionState state;
 	int			result;
@@ -1120,7 +1121,7 @@ text_position(text *t1, text *t2)
 	if (VARSIZE_ANY_EXHDR(t1) < 1 || VARSIZE_ANY_EXHDR(t2) < 1)
 		return 0;
 
-	text_position_setup(t1, t2, &state);
+	text_position_setup(t1, t2, collid, &state);
 	if (!text_position_next(&state))
 		result = 0;
 	else
@@ -1147,10 +1148,21 @@ text_position(text *t1, text *t2)
  */
 
 static void
-text_position_setup(text *t1, text *t2, TextPositionState *state)
+text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
+	pg_locale_t	mylocale = 0;
+
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
 
 	Assert(len1 > 0);
 	Assert(len2 > 0);
@@ -1429,6 +1441,22 @@ text_position_cleanup(TextPositionState *state)
 	/* no cleanup needed */
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1441,6 +1469,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1462,20 +1492,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1486,7 +1503,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * equal strings in the input - then we win big by avoiding expensive
 		 * collation-aware comparisons.
 		 */
-		if (len1 == len2 && memcmp(arg1, arg2, len1) == 0)
+		if ((!mylocale || mylocale->deterministic) &&
+			len1 == len2 && memcmp(arg1, arg2, len1) == 0)
 			return 0;
 
 #ifdef WIN32
@@ -1558,13 +1576,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 				ereport(ERROR,
 						(errmsg("could not compare Unicode strings: %m")));
 
-			/*
-			 * In some locales wcscoll() can claim that nonidentical strings
-			 * are equal.  Believing that would be bad news for a number of
-			 * reasons, so we follow Perl's lead and sort "equal" strings
-			 * according to strcmp (on the UTF-8 representation).
-			 */
-			if (result == 0)
+			/* Break tie if necessary. */
+			if (result == 0 &&
+				(!mylocale || mylocale->deterministic))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1649,13 +1663,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		else
 			result = strcoll(a1p, a2p);
 
-		/*
-		 * In some locales strcoll() can claim that nonidentical strings are
-		 * equal.  Believing that would be bad news for a number of reasons,
-		 * so we follow Perl's lead and sort "equal" strings according to
-		 * strcmp().
-		 */
-		if (result == 0)
+		/* Break tie if necessary. */
+		if (result == 0 &&
+			(!mylocale || mylocale->deterministic))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1699,33 +1709,51 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
-	 * don't even have to do a bitwise comparison if we can show the lengths
-	 * of the strings are unequal; which might save us from having to detoast
-	 * one or both values.
-	 */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = false;
+	check_collation_set(collid);
+
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
+		 * don't even have to do a bitwise comparison if we can show the lengths
+		 * of the strings are unequal; which might save us from having to detoast
+		 * one or both values.
+		 */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = false;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) == 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) == 0);
+		result = (text_cmp(arg1, arg2, collid) == 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1734,27 +1762,45 @@ texteq(PG_FUNCTION_ARGS)
 Datum
 textne(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/* See comment in texteq() */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = true;
+	check_collation_set(collid);
+
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/* See comment in texteq() */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = true;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) != 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) != 0);
+		result = (text_cmp(arg1, arg2, collid) != 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1825,10 +1871,22 @@ text_starts_with(PG_FUNCTION_ARGS)
 {
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	bool		result;
 	Size		len1,
 				len2;
 
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
+
 	len1 = toast_raw_datum_size(arg1);
 	len2 = toast_raw_datum_size(arg2);
 	if (len2 > len1)
@@ -1898,6 +1956,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1934,20 +1994,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2198,7 +2245,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	bool		arg1_match;
 
 	/* Fast pre-check for equality, as discussed in varstr_cmp() */
-	if (len1 == len2 && memcmp(a1p, a2p, len1) == 0)
+	if ((!sss->locale || sss->locale->deterministic) &&
+		len1 == len2 && memcmp(a1p, a2p, len1) == 0)
 	{
 		/*
 		 * No change in buf1 or buf2 contents, so avoid changing last_len1 or
@@ -2333,7 +2381,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	 * equal. Believing that would be bad news for a number of reasons, so we
 	 * follow Perl's lead and sort "equal" strings according to strcmp().
 	 */
-	if (result == 0)
+	if (result == 0 &&
+		(!sss->locale || sss->locale->deterministic))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2760,10 +2809,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2777,10 +2834,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2794,10 +2859,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2811,10 +2884,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -4121,7 +4202,7 @@ replace_text(PG_FUNCTION_ARGS)
 		PG_RETURN_TEXT_P(src_text);
 	}
 
-	text_position_setup(src_text, from_sub_text, &state);
+	text_position_setup(src_text, from_sub_text, PG_GET_COLLATION(), &state);
 
 	found = text_position_next(&state);
 
@@ -4482,7 +4563,7 @@ split_text(PG_FUNCTION_ARGS)
 			PG_RETURN_TEXT_P(cstring_to_text(""));
 	}
 
-	text_position_setup(inputstring, fldsep, &state);
+	text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 	/* identify bounds of first field */
 	start_ptr = VARDATA_ANY(inputstring);
@@ -4538,11 +4619,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4633,7 +4715,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 			int			lbs[1];
 
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4645,7 +4727,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 													 TEXTOID, -1, false, 'i'));
 		}
 
-		text_position_setup(inputstring, fldsep, &state);
+		text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 		start_ptr = VARDATA_ANY(inputstring);
 
@@ -4673,7 +4755,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4715,7 +4797,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 258a1d64cc..85dc0fbf8c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -181,13 +181,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index fba0ee8b84..f3bbaed992 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 3a89ad846a..1cadc7303b 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13232,6 +13232,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13249,28 +13250,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13297,6 +13305,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4da6719ce7..b43300c262 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 537fe5cef0..6fc57d4dd9 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -247,6 +249,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 3b789ee7cf..5f964436e0 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -688,6 +688,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -857,6 +858,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1869,6 +1871,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..840ba416a0 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 3bbdb5e2f7..b093a3c8ac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -53,7 +53,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 58db79203b..46d614f4fb 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -32,6 +32,7 @@ extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
 extern void apply_tlist_labeling(List *dest_tlist, List *src_tlist);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index ceec85db92..f622b9e512 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f95d165288..174c41aa64 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,6 +1100,714 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs;
+  x  
+-----
+ ABC
+ ghi
+ abc
+ def
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+   string_to_array   
+---------------------
+ {A,B,C,D,E,F,G,H,I}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+ ?column? 
+----------
+ f
+(1 row)
+
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test22_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test23_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test32_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test33_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index d33f04a3b5..6b245a7f28 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,6 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index a54b4a5a7c..872ff5966a 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0aeba3e202..1e97fb712e 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,6 +425,245 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+SELECT * FROM test22_1;
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+SELECT * FROM test23_1;
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+SELECT * FROM test32_1;
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+SELECT * FROM test33_1;
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index e882153244..4ca02b821d 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,6 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 843f511b3d..82d5a7edcd 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..f9edda6ab6
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,98 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false)");
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text PRIMARY KEY, b text)");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text COLLATE case_insensitive PRIMARY KEY, b text)");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text, b text)");
+$node_publisher->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text COLLATE case_insensitive, b text)");
+$node_subscriber->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	"CREATE PUBLICATION pub1 FOR ALL TABLES");
+
+$node_subscriber->safe_psql('postgres',
+	"CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr application_name=sub1' PUBLICATION pub1 WITH (copy_data = false)");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab1 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# Note: Even though the UPDATE command above only updates column "b",
+# the replication target will also update column "a", because the
+# whole row is shippped.
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab1 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive primary key');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab2 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab2 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive column with replica identity full');

base-commit: 727921f466a5234e41b27d34f8e859ca39a93f9e
-- 
2.20.1

From 1c3edcb60ea7b10282035da0687ff6f67745b380 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Feb 2019 15:45:46 +0100
Subject: [PATCH v6] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Discussion: https://www.postgresql.org/message-id/flat/1ccc668f-4cbc-0bef-af67-450b47cdfee7@2ndquadrant.com/
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  61 +-
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            | 100 ++-
 src/backend/access/spgist/spgtextproc.c       |   3 +-
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/commands/extension.c              |   6 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  14 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  39 +-
 src/backend/utils/adt/varchar.c               | 159 +++-
 src/backend/utils/adt/varlena.c               | 288 ++++---
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   4 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 708 ++++++++++++++++++
 .../regress/expected/collate.linux.utf8.out   |   5 +
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 239 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   7 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      |  98 +++
 66 files changed, 1973 insertions(+), 224 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index d641361aef..7c18eaa508 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 0fd792ff1a..45ed077654 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..555d1b4ac6 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,13 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>;
+    see <xref linkend="collation-nondeterministic"/>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
@@ -883,6 +885,55 @@ <title>Copying Collations</title>
    </para>
    </sect4>
    </sect3>
+
+   <sect3 id="collation-nondeterministic">
+    <title>Nondeterminstic Collations</title>
+
+    <para>
+     A collation is either <firstterm>deterministic</firstterm> or
+     <firstterm>nondeterministic</firstterm>.  A deterministic collation uses
+     deterministic comparisons, which means that it considers strings to be
+     equal only if they consist of the same byte sequence.  Nondeterministic
+     comparison may determine strings to be equal even if they consist of
+     different bytes.  Typical situations include case-insensitive comparison,
+     accent-insensitive comparison, as well as comparion of strings in
+     different Unicode normal forms.  It is up to the collation provider to
+     actually implement such insensitive comparisons; the deterministic flag
+     only determines whether ties are to be broken using bytewise comparison.
+     See also <ulink url="https://unicode.org/reports/tr10">Unicode Technical
+     Standard 10</ulink> for more information on the terminology.
+    </para>
+
+    <para>
+     To create a nondeterministic collation, specify the property
+     <literal>deterministic = false</literal> to <command>CREATE
+     COLLATION</command>, for example:
+<programlisting>
+CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
+</programlisting>
+     This example would use the standard Unicode collation in a
+     nondeterministic way.  In particular, this would allow strings in
+     different normal forms to be compared correctly.  More interesting
+     examples make use of the ICU customization facilities explained above.
+     For example:
+<programlisting>
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+</programlisting>
+    </para>
+
+    <para>
+     All standard and predefined collations are deterministic, all
+     user-defined collations are deterministic by default.  While
+     nondeterministic collations give a more <quote>correct</quote> behavior,
+     especially when considering the full power of Unicode and its many
+     special cases, they also have some drawbacks.  Foremost, their use leads
+     to a performance penalty.  Also, certain operations are not possible with
+     nondeterministic collations, such as pattern matching operations.
+     Therefore, they should be used only in cases where they are specifically
+     wanted.
+    </para>
+   </sect3>
   </sect2>
  </sect1>
 
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 86ff4e5c9e..48f7a48e0d 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3962,6 +3962,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..785e02a5fe 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,15 +244,51 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/*
-	 * Note: this is currently identical in behavior to hashvarlena, but keep
-	 * it as a separate function in case we someday want to do something
-	 * different in non-C locales.  (See also hashbpchar, if so.)
-	 */
-	result = hash_any((unsigned char *) VARDATA_ANY(key),
-					  VARSIZE_ANY_EXHDR(key));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -262,12 +300,52 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/* Same approach as hashtext */
-	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
-							   VARSIZE_ANY_EXHDR(key),
-							   PG_GETARG_INT64(1));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 39cd391529..d22998c54b 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -630,7 +630,8 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
 			 * query (prefix) string, so we don't need to check it again.
 			 */
 			res = (level >= queryLen) ||
-				DatumGetBool(DirectFunctionCall2(text_starts_with,
+				DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
+													 PG_GET_COLLATION(),
 												 out->leafValue,
 												 PointerGetDatum(query)));
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..d4723fced8 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -901,7 +901,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		{
 			const char *qSchemaName = quote_identifier(schemaName);
 
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("@extschema@"),
 										CStringGetTextDatum(qSchemaName));
@@ -913,7 +914,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		 */
 		if (control->module_pathname)
 		{
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("MODULE_PATHNAME"),
 										CStringGetTextDatum(control->module_pathname));
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index db3777d15e..bc3e05cd1b 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3327,6 +3327,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3387,6 +3388,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3404,7 +3406,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index a9d80e692b..870a730a66 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -156,6 +157,7 @@ BuildTupleHashTableExt(PlanState *parent,
 					   int numCols, AttrNumber *keyColIdx,
 					   const Oid *eqfuncoids,
 					   FmgrInfo *hashfunctions,
+					   Oid *collations,
 					   long nbuckets, Size additionalsize,
 					   MemoryContext metacxt,
 					   MemoryContext tablecxt,
@@ -178,6 +180,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -213,7 +216,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													NULL);
 
 	/*
@@ -241,6 +244,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt,
@@ -251,6 +255,7 @@ BuildTupleHashTable(PlanState *parent,
 								  numCols, keyColIdx,
 								  eqfuncoids,
 								  hashfunctions,
+								  collations,
 								  nbuckets, additionalsize,
 								  tablecxt,
 								  tablecxt,
@@ -422,8 +427,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 2a7bc01563..0341250f1d 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1218,6 +1218,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 589573b879..d9d5a7b78b 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -95,6 +95,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -261,7 +263,8 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										values[attrnum],
 										slot->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index bae7989a42..47161afbd4 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -746,15 +746,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1287,6 +1286,7 @@ build_hash_table(AggState *aggstate)
 														perhash->hashGrpColIdxHash,
 														perhash->eqfuncoids,
 														perhash->hashfunctions,
+														perhash->aggnode->grpCollations,
 														perhash->aggnode->numGroups,
 														additionalsize,
 														aggstate->ss.ps.state->es_query_cxt,
@@ -2381,6 +2381,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2392,6 +2393,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3155,6 +3157,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 9b74ed3208..9c5eed7def 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 												node->dupColIdx,
 												rustate->eqfuncoids,
 												rustate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												rustate->ps.state->es_query_cxt,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 26aeaee083..044246aa09 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												   node->dupColIdx,
 												   setopstate->eqfuncoids,
 												   setopstate->hashfunctions,
+												   node->dupCollations,
 												   node->numGroups,
 												   0,
 												   setopstate->ps.state->es_query_cxt,
@@ -554,6 +555,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index d7d076758c..749b4eced3 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -514,6 +514,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 												 node->keyColIdx,
 												 node->tab_eq_funcoids,
 												 node->tab_hash_funcs,
+												 node->tab_collations,
 												 nbuckets,
 												 0,
 												 node->planstate->state->es_query_cxt,
@@ -541,6 +542,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 													 node->keyColIdx,
 													 node->tab_eq_funcoids,
 													 node->tab_hash_funcs,
+													 node->tab_collations,
 													 nbuckets,
 													 0,
 													 node->planstate->state->es_query_cxt,
@@ -642,6 +644,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -679,8 +682,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -722,6 +725,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -817,6 +821,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -915,6 +920,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -965,6 +971,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -1001,6 +1010,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 157ac042b8..b090828c01 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e15724bb0e..ee62cfc4da 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 65302fe65b..64ce615b90 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 5aa42242a9..df32e4862b 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1676,6 +1676,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2142,6 +2143,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2161,6 +2163,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2183,9 +2186,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2211,6 +2216,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2289,6 +2295,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 236f506cfb..eaf11d9b87 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -260,14 +260,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1387,6 +1387,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1453,6 +1454,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1463,7 +1465,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1501,6 +1505,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1883,6 +1888,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1949,6 +1956,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2110,6 +2119,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2147,6 +2157,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2246,9 +2257,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2270,6 +2283,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2280,11 +2294,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2295,6 +2311,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2304,9 +2321,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5326,10 +5345,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5339,11 +5360,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6015,7 +6038,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6031,6 +6054,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6046,8 +6070,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6060,9 +6084,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6087,6 +6113,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6095,6 +6122,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6118,6 +6146,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6132,6 +6161,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6140,6 +6170,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6147,6 +6178,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6162,6 +6194,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6177,6 +6210,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6245,6 +6279,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6252,6 +6287,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6296,6 +6332,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6309,6 +6346,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6317,6 +6355,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6326,6 +6365,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 14d1c67a94..bb3b7969f2 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -503,6 +503,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index d478ae7e19..c62450f78d 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2657,7 +2657,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2678,7 +2678,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 8c9721935d..bc1f00d33e 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2154,6 +2154,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2174,7 +2175,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 5b2917d159..61deefbbc8 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3958,7 +3958,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(*locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 853c9c01e9..a61fb542f2 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(const char *t, int tlen, const char *p, int plen,
 static int SB_IMatchText(const char *t, int tlen, const char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(const char *s, int slen, const char *p, int plen);
+static int	GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(const char *s, int slen, const char *p, int plen)
+GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
 {
+	if (collation)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 2d384a9944..4db2d0d0e1 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e1aa3d0044..55488f1192 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -778,6 +778,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -786,6 +788,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -918,6 +922,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -926,6 +932,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1069,6 +1077,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1080,6 +1090,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1257,6 +1269,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1268,6 +1282,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1444,6 +1460,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1455,6 +1473,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -2901,11 +2921,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
-	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
+	 */
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /* ----------
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index c866af022f..0869018bcc 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -24,6 +24,7 @@
 #include "nodes/supportnodes.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -718,6 +719,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -726,18 +743,30 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = false;
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = false;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -753,18 +782,28 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = true;
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = true;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -934,23 +973,60 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 /*
  * bpchar needs a specialized hash function because we want to ignore
  * trailing blanks in comparisons.
- *
- * Note: currently there is no need for locale-specific behavior here,
- * but if we ever change the semantics of bpchar comparison to trust
- * strcoll() completely, we'd need to do something different in non-C locales.
  */
 Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any((unsigned char *) keydata, keylen);
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) keydata, keylen);
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -962,15 +1038,56 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any_extended((unsigned char *) keydata, keylen,
-							   PG_GETARG_INT64(1));
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) keydata, keylen,
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 693ccc5149..b94b15eea2 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -122,13 +122,14 @@ static text *text_substring(Datum str,
 			   int32 length,
 			   bool length_not_specified);
 static text *text_overlay(text *t1, text *t2, int sp, int sl);
-static int	text_position(text *t1, text *t2);
-static void text_position_setup(text *t1, text *t2, TextPositionState *state);
+static int	text_position(text *t1, text *t2, Oid collid);
+static void text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state);
 static bool text_position_next(TextPositionState *state);
 static char *text_position_next_internal(char *start_ptr, TextPositionState *state);
 static char *text_position_get_match_ptr(TextPositionState *state);
 static int	text_position_get_match_pos(TextPositionState *state);
 static void text_position_cleanup(TextPositionState *state);
+static void check_collation_set(Oid collid);
 static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static bytea *bytea_catenate(bytea *t1, bytea *t2);
 static bytea *bytea_substring(Datum str,
@@ -1094,7 +1095,7 @@ textpos(PG_FUNCTION_ARGS)
 	text	   *str = PG_GETARG_TEXT_PP(0);
 	text	   *search_str = PG_GETARG_TEXT_PP(1);
 
-	PG_RETURN_INT32((int32) text_position(str, search_str));
+	PG_RETURN_INT32((int32) text_position(str, search_str, PG_GET_COLLATION()));
 }
 
 /*
@@ -1112,7 +1113,7 @@ textpos(PG_FUNCTION_ARGS)
  *	functions.
  */
 static int
-text_position(text *t1, text *t2)
+text_position(text *t1, text *t2, Oid collid)
 {
 	TextPositionState state;
 	int			result;
@@ -1120,7 +1121,7 @@ text_position(text *t1, text *t2)
 	if (VARSIZE_ANY_EXHDR(t1) < 1 || VARSIZE_ANY_EXHDR(t2) < 1)
 		return 0;
 
-	text_position_setup(t1, t2, &state);
+	text_position_setup(t1, t2, collid, &state);
 	if (!text_position_next(&state))
 		result = 0;
 	else
@@ -1147,10 +1148,21 @@ text_position(text *t1, text *t2)
  */
 
 static void
-text_position_setup(text *t1, text *t2, TextPositionState *state)
+text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
+	pg_locale_t	mylocale = 0;
+
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
 
 	Assert(len1 > 0);
 	Assert(len2 > 0);
@@ -1429,6 +1441,22 @@ text_position_cleanup(TextPositionState *state)
 	/* no cleanup needed */
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1441,6 +1469,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1462,20 +1492,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1486,7 +1503,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		 * equal strings in the input - then we win big by avoiding expensive
 		 * collation-aware comparisons.
 		 */
-		if (len1 == len2 && memcmp(arg1, arg2, len1) == 0)
+		if ((!mylocale || mylocale->deterministic) &&
+			len1 == len2 && memcmp(arg1, arg2, len1) == 0)
 			return 0;
 
 #ifdef WIN32
@@ -1558,13 +1576,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 				ereport(ERROR,
 						(errmsg("could not compare Unicode strings: %m")));
 
-			/*
-			 * In some locales wcscoll() can claim that nonidentical strings
-			 * are equal.  Believing that would be bad news for a number of
-			 * reasons, so we follow Perl's lead and sort "equal" strings
-			 * according to strcmp (on the UTF-8 representation).
-			 */
-			if (result == 0)
+			/* Break tie if necessary. */
+			if (result == 0 &&
+				(!mylocale || mylocale->deterministic))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1649,13 +1663,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		else
 			result = strcoll(a1p, a2p);
 
-		/*
-		 * In some locales strcoll() can claim that nonidentical strings are
-		 * equal.  Believing that would be bad news for a number of reasons,
-		 * so we follow Perl's lead and sort "equal" strings according to
-		 * strcmp().
-		 */
-		if (result == 0)
+		/* Break tie if necessary. */
+		if (result == 0 &&
+			(!mylocale || mylocale->deterministic))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1699,33 +1709,51 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
-	 * don't even have to do a bitwise comparison if we can show the lengths
-	 * of the strings are unequal; which might save us from having to detoast
-	 * one or both values.
-	 */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = false;
+	check_collation_set(collid);
+
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
+		 * don't even have to do a bitwise comparison if we can show the lengths
+		 * of the strings are unequal; which might save us from having to detoast
+		 * one or both values.
+		 */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = false;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) == 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) == 0);
+		result = (text_cmp(arg1, arg2, collid) == 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1734,27 +1762,45 @@ texteq(PG_FUNCTION_ARGS)
 Datum
 textne(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/* See comment in texteq() */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = true;
+	check_collation_set(collid);
+
+	if (collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/* See comment in texteq() */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = true;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) != 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) != 0);
+		result = (text_cmp(arg1, arg2, collid) != 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1825,10 +1871,22 @@ text_starts_with(PG_FUNCTION_ARGS)
 {
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	bool		result;
 	Size		len1,
 				len2;
 
+	check_collation_set(collid);
+
+	if (collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
+
 	len1 = toast_raw_datum_size(arg1);
 	len2 = toast_raw_datum_size(arg2);
 	if (len2 > len1)
@@ -1898,6 +1956,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1934,20 +1994,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2198,7 +2245,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	bool		arg1_match;
 
 	/* Fast pre-check for equality, as discussed in varstr_cmp() */
-	if (len1 == len2 && memcmp(a1p, a2p, len1) == 0)
+	if ((!sss->locale || sss->locale->deterministic) &&
+		len1 == len2 && memcmp(a1p, a2p, len1) == 0)
 	{
 		/*
 		 * No change in buf1 or buf2 contents, so avoid changing last_len1 or
@@ -2333,7 +2381,8 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	 * equal. Believing that would be bad news for a number of reasons, so we
 	 * follow Perl's lead and sort "equal" strings according to strcmp().
 	 */
-	if (result == 0)
+	if (result == 0 &&
+		(!sss->locale || sss->locale->deterministic))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2760,10 +2809,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2777,10 +2834,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2794,10 +2859,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2811,10 +2884,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -4121,7 +4202,7 @@ replace_text(PG_FUNCTION_ARGS)
 		PG_RETURN_TEXT_P(src_text);
 	}
 
-	text_position_setup(src_text, from_sub_text, &state);
+	text_position_setup(src_text, from_sub_text, PG_GET_COLLATION(), &state);
 
 	found = text_position_next(&state);
 
@@ -4482,7 +4563,7 @@ split_text(PG_FUNCTION_ARGS)
 			PG_RETURN_TEXT_P(cstring_to_text(""));
 	}
 
-	text_position_setup(inputstring, fldsep, &state);
+	text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 	/* identify bounds of first field */
 	start_ptr = VARDATA_ANY(inputstring);
@@ -4538,11 +4619,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4633,7 +4715,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 			int			lbs[1];
 
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4645,7 +4727,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 													 TEXTOID, -1, false, 'i'));
 		}
 
-		text_position_setup(inputstring, fldsep, &state);
+		text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 		start_ptr = VARDATA_ANY(inputstring);
 
@@ -4673,7 +4755,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4715,7 +4797,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 78dd5714fa..bb9ae8fd0c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -171,13 +171,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e88c45d268..59e6bcd856 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index a08bc4ecae..f0c7765f74 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13290,6 +13290,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13307,28 +13308,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13355,6 +13363,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4da6719ce7..b43300c262 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 7a63e9a7cc..bca10e75e8 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -129,6 +131,7 @@ extern TupleHashTable BuildTupleHashTableExt(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext metacxt,
 					MemoryContext tablecxt,
@@ -257,6 +260,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 3b789ee7cf..5f964436e0 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -688,6 +688,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -857,6 +858,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1869,6 +1871,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..840ba416a0 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 3bbdb5e2f7..b093a3c8ac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -53,7 +53,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 58db79203b..46d614f4fb 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -32,6 +32,7 @@ extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
 extern void apply_tlist_labeling(List *dest_tlist, List *src_tlist);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 16b0b1d2dc..b9a9ecb7cc 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f95d165288..174c41aa64 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,6 +1100,714 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+ abc
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs;
+  x  
+-----
+ ABC
+ ghi
+ abc
+ def
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+   string_to_array   
+---------------------
+ {A,B,C,D,E,F,G,H,I}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+  x  
+-----
+ abc
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+  x  
+-----
+ ABC
+ ghi
+ def
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci;
+  x  
+-----
+ ghi
+ def
+ abc
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+ ?column? 
+----------
+ f
+(1 row)
+
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test22_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test23_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+ a |  b  
+---+-----
+ 1 | def
+(1 row)
+
+SELECT * FROM test32_1;
+ a |  b  
+---+-----
+ 2 | DEF
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test33_1;
+ a |  b  
+---+-----
+ 1 | def
+ 2 | DEF
+(2 rows)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index d33f04a3b5..6b245a7f28 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,6 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index cc3f5f3737..edd6d1ef7f 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0aeba3e202..1e97fb712e 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,6 +425,245 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test22_0;
+SELECT * FROM test22_1;
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test23_0;
+SELECT * FROM test23_1;
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT * FROM test32_0;
+SELECT * FROM test32_1;
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition
+SELECT * FROM test33_0;
+SELECT * FROM test33_1;
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index e882153244..4ca02b821d 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,6 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 8bca1f5d55..7e0ef0554a 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..f9edda6ab6
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,98 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false)");
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text PRIMARY KEY, b text)");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab1 (a text COLLATE case_insensitive PRIMARY KEY, b text)");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab1 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text, b text)");
+$node_publisher->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('abc', 'abc'), ('def', 'def')");
+
+$node_subscriber->safe_psql('postgres',
+   "CREATE TABLE tab2 (a text COLLATE case_insensitive, b text)");
+$node_subscriber->safe_psql('postgres',
+   "ALTER TABLE tab2 REPLICA IDENTITY FULL");
+
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO tab2 VALUES ('ABC', 'abc'), ('GHI', 'ghi')");
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	"CREATE PUBLICATION pub1 FOR ALL TABLES");
+
+$node_subscriber->safe_psql('postgres',
+	"CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr application_name=sub1' PUBLICATION pub1 WITH (copy_data = false)");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab1 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+# Note: Even though the UPDATE command above only updates column "b",
+# the replication target will also update column "a", because the
+# whole row is shippped.
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab1 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive primary key');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	"UPDATE tab2 SET b = 'xyz' WHERE b = 'abc'");
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', "SELECT a, b FROM tab2 ORDER BY a"),
+   qq(abc|xyz
+GHI|ghi),
+  'update of case insensitive column with replica identity full');

base-commit: 90cfa49003831dbea109a9f0a7924dc95c1bf1c5
-- 
2.20.1

From 04a2192c880a257775e4d3c2a07e48f41fb2815d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 21 Feb 2019 17:59:03 +0100
Subject: [PATCH v7] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Discussion: https://www.postgresql.org/message-id/flat/1ccc668f-4cbc-0bef-af67-450b47cdfee7@2ndquadrant.com/
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  61 +-
 doc/src/sgml/citext.sgml                      |  21 +
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            | 100 ++-
 src/backend/access/spgist/spgtextproc.c       |   3 +-
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/commands/extension.c              |   6 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  14 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  39 +-
 src/backend/utils/adt/varchar.c               | 161 ++++-
 src/backend/utils/adt/varlena.c               | 290 +++++---
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   4 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 684 ++++++++++++++++++
 .../regress/expected/collate.linux.utf8.out   |   5 +
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 235 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   7 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      | 103 +++
 67 files changed, 1972 insertions(+), 227 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index d641361aef..7c18eaa508 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 0fd792ff1a..45ed077654 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..555d1b4ac6 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,13 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>;
+    see <xref linkend="collation-nondeterministic"/>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
@@ -883,6 +885,55 @@ <title>Copying Collations</title>
    </para>
    </sect4>
    </sect3>
+
+   <sect3 id="collation-nondeterministic">
+    <title>Nondeterminstic Collations</title>
+
+    <para>
+     A collation is either <firstterm>deterministic</firstterm> or
+     <firstterm>nondeterministic</firstterm>.  A deterministic collation uses
+     deterministic comparisons, which means that it considers strings to be
+     equal only if they consist of the same byte sequence.  Nondeterministic
+     comparison may determine strings to be equal even if they consist of
+     different bytes.  Typical situations include case-insensitive comparison,
+     accent-insensitive comparison, as well as comparion of strings in
+     different Unicode normal forms.  It is up to the collation provider to
+     actually implement such insensitive comparisons; the deterministic flag
+     only determines whether ties are to be broken using bytewise comparison.
+     See also <ulink url="https://unicode.org/reports/tr10">Unicode Technical
+     Standard 10</ulink> for more information on the terminology.
+    </para>
+
+    <para>
+     To create a nondeterministic collation, specify the property
+     <literal>deterministic = false</literal> to <command>CREATE
+     COLLATION</command>, for example:
+<programlisting>
+CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
+</programlisting>
+     This example would use the standard Unicode collation in a
+     nondeterministic way.  In particular, this would allow strings in
+     different normal forms to be compared correctly.  More interesting
+     examples make use of the ICU customization facilities explained above.
+     For example:
+<programlisting>
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+</programlisting>
+    </para>
+
+    <para>
+     All standard and predefined collations are deterministic, all
+     user-defined collations are deterministic by default.  While
+     nondeterministic collations give a more <quote>correct</quote> behavior,
+     especially when considering the full power of Unicode and its many
+     special cases, they also have some drawbacks.  Foremost, their use leads
+     to a performance penalty.  Also, certain operations are not possible with
+     nondeterministic collations, such as pattern matching operations.
+     Therefore, they should be used only in cases where they are specifically
+     wanted.
+    </para>
+   </sect3>
   </sect2>
  </sect1>
 
diff --git a/doc/src/sgml/citext.sgml b/doc/src/sgml/citext.sgml
index b1fe7101b2..85aa339d8b 100644
--- a/doc/src/sgml/citext.sgml
+++ b/doc/src/sgml/citext.sgml
@@ -14,6 +14,16 @@ <title>citext</title>
   exactly like <type>text</type>.
  </para>
 
+ <tip>
+  <para>
+   Consider using <firstterm>nondeterministic collations</firstterm> (see
+   <xref linkend="collation-nondeterministic"/>) instead of this module.  They
+   can be used for case-insensitive comparisons, accent-insensitive
+   comparisons, and other combinations, and they handle more Unicode special
+   cases correctly.
+  </para>
+ </tip>
+
  <sect2>
   <title>Rationale</title>
 
@@ -246,6 +256,17 @@ <title>Limitations</title>
       will be invoked instead.
     </para>
     </listitem>
+
+    <listitem>
+     <para>
+      The approach of lower-casing strings for comparison does not handle some
+      Unicode special cases correctly, for example when one upper-case letter
+      has two lower-case letter equivalents.  Unicode distinguishes between
+      <firstterm>case mapping</firstterm> and <firstterm>case
+      folding</firstterm> for this reason.  Use nondeterministic collations
+      instead of <type>citext</type> to handle that correctly.
+     </para>
+    </listitem>
    </itemizedlist>
  </sect2>
 
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 86ff4e5c9e..48f7a48e0d 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3962,6 +3962,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..cc116f5ece 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,15 +244,51 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/*
-	 * Note: this is currently identical in behavior to hashvarlena, but keep
-	 * it as a separate function in case we someday want to do something
-	 * different in non-C locales.  (See also hashbpchar, if so.)
-	 */
-	result = hash_any((unsigned char *) VARDATA_ANY(key),
-					  VARSIZE_ANY_EXHDR(key));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -262,12 +300,52 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/* Same approach as hashtext */
-	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
-							   VARSIZE_ANY_EXHDR(key),
-							   PG_GETARG_INT64(1));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 39cd391529..d22998c54b 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -630,7 +630,8 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
 			 * query (prefix) string, so we don't need to check it again.
 			 */
 			res = (level >= queryLen) ||
-				DatumGetBool(DirectFunctionCall2(text_starts_with,
+				DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
+													 PG_GET_COLLATION(),
 												 out->leafValue,
 												 PointerGetDatum(query)));
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..d4723fced8 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -901,7 +901,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		{
 			const char *qSchemaName = quote_identifier(schemaName);
 
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("@extschema@"),
 										CStringGetTextDatum(qSchemaName));
@@ -913,7 +914,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		 */
 		if (control->module_pathname)
 		{
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("MODULE_PATHNAME"),
 										CStringGetTextDatum(control->module_pathname));
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index db3777d15e..bc3e05cd1b 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3327,6 +3327,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3387,6 +3388,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3404,7 +3406,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index a9d80e692b..870a730a66 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -156,6 +157,7 @@ BuildTupleHashTableExt(PlanState *parent,
 					   int numCols, AttrNumber *keyColIdx,
 					   const Oid *eqfuncoids,
 					   FmgrInfo *hashfunctions,
+					   Oid *collations,
 					   long nbuckets, Size additionalsize,
 					   MemoryContext metacxt,
 					   MemoryContext tablecxt,
@@ -178,6 +180,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -213,7 +216,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													NULL);
 
 	/*
@@ -241,6 +244,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt,
@@ -251,6 +255,7 @@ BuildTupleHashTable(PlanState *parent,
 								  numCols, keyColIdx,
 								  eqfuncoids,
 								  hashfunctions,
+								  collations,
 								  nbuckets, additionalsize,
 								  tablecxt,
 								  tablecxt,
@@ -422,8 +427,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 2a7bc01563..0341250f1d 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1218,6 +1218,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 589573b879..d9d5a7b78b 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -95,6 +95,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -261,7 +263,8 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										values[attrnum],
 										slot->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index bae7989a42..47161afbd4 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -746,15 +746,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1287,6 +1286,7 @@ build_hash_table(AggState *aggstate)
 														perhash->hashGrpColIdxHash,
 														perhash->eqfuncoids,
 														perhash->hashfunctions,
+														perhash->aggnode->grpCollations,
 														perhash->aggnode->numGroups,
 														additionalsize,
 														aggstate->ss.ps.state->es_query_cxt,
@@ -2381,6 +2381,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2392,6 +2393,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3155,6 +3157,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 9b74ed3208..9c5eed7def 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 												node->dupColIdx,
 												rustate->eqfuncoids,
 												rustate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												rustate->ps.state->es_query_cxt,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 26aeaee083..044246aa09 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												   node->dupColIdx,
 												   setopstate->eqfuncoids,
 												   setopstate->hashfunctions,
+												   node->dupCollations,
 												   node->numGroups,
 												   0,
 												   setopstate->ps.state->es_query_cxt,
@@ -554,6 +555,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index d7d076758c..749b4eced3 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -514,6 +514,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 												 node->keyColIdx,
 												 node->tab_eq_funcoids,
 												 node->tab_hash_funcs,
+												 node->tab_collations,
 												 nbuckets,
 												 0,
 												 node->planstate->state->es_query_cxt,
@@ -541,6 +542,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 													 node->keyColIdx,
 													 node->tab_eq_funcoids,
 													 node->tab_hash_funcs,
+													 node->tab_collations,
 													 nbuckets,
 													 0,
 													 node->planstate->state->es_query_cxt,
@@ -642,6 +644,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -679,8 +682,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -722,6 +725,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -817,6 +821,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -915,6 +920,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -965,6 +971,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -1001,6 +1010,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 157ac042b8..b090828c01 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e15724bb0e..ee62cfc4da 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 65302fe65b..64ce615b90 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 5aa42242a9..df32e4862b 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1676,6 +1676,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2142,6 +2143,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2161,6 +2163,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2183,9 +2186,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2211,6 +2216,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2289,6 +2295,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 236f506cfb..eaf11d9b87 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -260,14 +260,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1387,6 +1387,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1453,6 +1454,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1463,7 +1465,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1501,6 +1505,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1883,6 +1888,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1949,6 +1956,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2110,6 +2119,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2147,6 +2157,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2246,9 +2257,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2270,6 +2283,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2280,11 +2294,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2295,6 +2311,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2304,9 +2321,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5326,10 +5345,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5339,11 +5360,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6015,7 +6038,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6031,6 +6054,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6046,8 +6070,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6060,9 +6084,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6087,6 +6113,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6095,6 +6122,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6118,6 +6146,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6132,6 +6161,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6140,6 +6170,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6147,6 +6178,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6162,6 +6194,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6177,6 +6210,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6245,6 +6279,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6252,6 +6287,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6296,6 +6332,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6309,6 +6346,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6317,6 +6355,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6326,6 +6365,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 14d1c67a94..bb3b7969f2 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -503,6 +503,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index d478ae7e19..c62450f78d 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2657,7 +2657,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2678,7 +2678,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index 8c9721935d..bc1f00d33e 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2154,6 +2154,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2174,7 +2175,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 5b2917d159..61deefbbc8 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3958,7 +3958,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(*locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 853c9c01e9..704e5720cf 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(const char *t, int tlen, const char *p, int plen,
 static int SB_IMatchText(const char *t, int tlen, const char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(const char *s, int slen, const char *p, int plen);
+static int	GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(const char *s, int slen, const char *p, int plen)
+GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
 {
+	if (collation && !lc_ctype_is_c(collation) && collation != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 2d384a9944..4db2d0d0e1 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index e1aa3d0044..55488f1192 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -778,6 +778,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -786,6 +788,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -918,6 +922,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -926,6 +932,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = "AND";
 					queryoids[i] = pk_type;
 				}
@@ -1069,6 +1077,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1080,6 +1090,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1257,6 +1269,8 @@ ri_setnull(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1268,6 +1282,8 @@ ri_setnull(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -1444,6 +1460,8 @@ ri_setdefault(TriggerData *trigdata)
 				{
 					Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 					Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+					Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+					Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 					quoteOneName(attname,
 								 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1455,6 +1473,8 @@ ri_setdefault(TriggerData *trigdata)
 									paramname, pk_type,
 									riinfo->pf_eq_oprs[i],
 									attname, fk_type);
+					if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+						ri_GenerateQualCollation(&querybuf, pk_coll);
 					querysep = ",";
 					qualsep = "AND";
 					queryoids[i] = pk_type;
@@ -2901,11 +2921,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
-	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
+	 */
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /* ----------
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index c866af022f..26c4b0178f 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -24,6 +24,7 @@
 #include "nodes/supportnodes.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -718,6 +719,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -726,18 +743,31 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = false;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = false;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -753,18 +783,29 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = true;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = true;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -934,23 +975,60 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 /*
  * bpchar needs a specialized hash function because we want to ignore
  * trailing blanks in comparisons.
- *
- * Note: currently there is no need for locale-specific behavior here,
- * but if we ever change the semantics of bpchar comparison to trust
- * strcoll() completely, we'd need to do something different in non-C locales.
  */
 Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any((unsigned char *) keydata, keylen);
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) keydata, keylen);
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -962,15 +1040,56 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any_extended((unsigned char *) keydata, keylen,
-							   PG_GETARG_INT64(1));
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) keydata, keylen,
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 693ccc5149..1e5b4d5cc7 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -122,13 +122,14 @@ static text *text_substring(Datum str,
 			   int32 length,
 			   bool length_not_specified);
 static text *text_overlay(text *t1, text *t2, int sp, int sl);
-static int	text_position(text *t1, text *t2);
-static void text_position_setup(text *t1, text *t2, TextPositionState *state);
+static int	text_position(text *t1, text *t2, Oid collid);
+static void text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state);
 static bool text_position_next(TextPositionState *state);
 static char *text_position_next_internal(char *start_ptr, TextPositionState *state);
 static char *text_position_get_match_ptr(TextPositionState *state);
 static int	text_position_get_match_pos(TextPositionState *state);
 static void text_position_cleanup(TextPositionState *state);
+static void check_collation_set(Oid collid);
 static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static bytea *bytea_catenate(bytea *t1, bytea *t2);
 static bytea *bytea_substring(Datum str,
@@ -1094,7 +1095,7 @@ textpos(PG_FUNCTION_ARGS)
 	text	   *str = PG_GETARG_TEXT_PP(0);
 	text	   *search_str = PG_GETARG_TEXT_PP(1);
 
-	PG_RETURN_INT32((int32) text_position(str, search_str));
+	PG_RETURN_INT32((int32) text_position(str, search_str, PG_GET_COLLATION()));
 }
 
 /*
@@ -1112,7 +1113,7 @@ textpos(PG_FUNCTION_ARGS)
  *	functions.
  */
 static int
-text_position(text *t1, text *t2)
+text_position(text *t1, text *t2, Oid collid)
 {
 	TextPositionState state;
 	int			result;
@@ -1120,7 +1121,7 @@ text_position(text *t1, text *t2)
 	if (VARSIZE_ANY_EXHDR(t1) < 1 || VARSIZE_ANY_EXHDR(t2) < 1)
 		return 0;
 
-	text_position_setup(t1, t2, &state);
+	text_position_setup(t1, t2, collid, &state);
 	if (!text_position_next(&state))
 		result = 0;
 	else
@@ -1147,10 +1148,21 @@ text_position(text *t1, text *t2)
  */
 
 static void
-text_position_setup(text *t1, text *t2, TextPositionState *state)
+text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
+	pg_locale_t	mylocale = 0;
+
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
 
 	Assert(len1 > 0);
 	Assert(len2 > 0);
@@ -1429,6 +1441,22 @@ text_position_cleanup(TextPositionState *state)
 	/* no cleanup needed */
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1441,6 +1469,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1462,20 +1492,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1558,13 +1575,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 				ereport(ERROR,
 						(errmsg("could not compare Unicode strings: %m")));
 
-			/*
-			 * In some locales wcscoll() can claim that nonidentical strings
-			 * are equal.  Believing that would be bad news for a number of
-			 * reasons, so we follow Perl's lead and sort "equal" strings
-			 * according to strcmp (on the UTF-8 representation).
-			 */
-			if (result == 0)
+			/* Break tie if necessary. */
+			if (result == 0 &&
+				(!mylocale || mylocale->deterministic))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1649,13 +1662,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		else
 			result = strcoll(a1p, a2p);
 
-		/*
-		 * In some locales strcoll() can claim that nonidentical strings are
-		 * equal.  Believing that would be bad news for a number of reasons,
-		 * so we follow Perl's lead and sort "equal" strings according to
-		 * strcmp().
-		 */
-		if (result == 0)
+		/* Break tie if necessary. */
+		if (result == 0 &&
+			(!mylocale || mylocale->deterministic))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1699,33 +1708,52 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
-	 * don't even have to do a bitwise comparison if we can show the lengths
-	 * of the strings are unequal; which might save us from having to detoast
-	 * one or both values.
-	 */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = false;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
+		 * don't even have to do a bitwise comparison if we can show the lengths
+		 * of the strings are unequal; which might save us from having to detoast
+		 * one or both values.
+		 */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = false;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) == 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) == 0);
+		result = (text_cmp(arg1, arg2, collid) == 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1734,27 +1762,46 @@ texteq(PG_FUNCTION_ARGS)
 Datum
 textne(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/* See comment in texteq() */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = true;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/* See comment in texteq() */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = true;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) != 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) != 0);
+		result = (text_cmp(arg1, arg2, collid) != 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1825,10 +1872,22 @@ text_starts_with(PG_FUNCTION_ARGS)
 {
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	bool		result;
 	Size		len1,
 				len2;
 
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
+
 	len1 = toast_raw_datum_size(arg1);
 	len2 = toast_raw_datum_size(arg2);
 	if (len2 > len1)
@@ -1898,6 +1957,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1934,20 +1995,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2328,12 +2376,9 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	else
 		result = strcoll(sss->buf1, sss->buf2);
 
-	/*
-	 * In some locales strcoll() can claim that nonidentical strings are
-	 * equal. Believing that would be bad news for a number of reasons, so we
-	 * follow Perl's lead and sort "equal" strings according to strcmp().
-	 */
-	if (result == 0)
+	/* Break tie if necessary. */
+	if (result == 0 &&
+		(!sss->locale || sss->locale->deterministic))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2760,10 +2805,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2777,10 +2830,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2794,10 +2855,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2811,10 +2880,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -4121,7 +4198,7 @@ replace_text(PG_FUNCTION_ARGS)
 		PG_RETURN_TEXT_P(src_text);
 	}
 
-	text_position_setup(src_text, from_sub_text, &state);
+	text_position_setup(src_text, from_sub_text, PG_GET_COLLATION(), &state);
 
 	found = text_position_next(&state);
 
@@ -4482,7 +4559,7 @@ split_text(PG_FUNCTION_ARGS)
 			PG_RETURN_TEXT_P(cstring_to_text(""));
 	}
 
-	text_position_setup(inputstring, fldsep, &state);
+	text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 	/* identify bounds of first field */
 	start_ptr = VARDATA_ANY(inputstring);
@@ -4538,11 +4615,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4633,7 +4711,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 			int			lbs[1];
 
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4645,7 +4723,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 													 TEXTOID, -1, false, 'i'));
 		}
 
-		text_position_setup(inputstring, fldsep, &state);
+		text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 		start_ptr = VARDATA_ANY(inputstring);
 
@@ -4673,7 +4751,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4715,7 +4793,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 78dd5714fa..bb9ae8fd0c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -171,13 +171,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e88c45d268..59e6bcd856 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index a08bc4ecae..f0c7765f74 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13290,6 +13290,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13307,28 +13308,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13355,6 +13363,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4da6719ce7..b43300c262 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4092,7 +4092,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4120,6 +4120,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 7a63e9a7cc..bca10e75e8 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -129,6 +131,7 @@ extern TupleHashTable BuildTupleHashTableExt(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext metacxt,
 					MemoryContext tablecxt,
@@ -257,6 +260,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 3b789ee7cf..5f964436e0 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -688,6 +688,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -857,6 +858,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1869,6 +1871,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..840ba416a0 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 3bbdb5e2f7..b093a3c8ac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -53,7 +53,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 58db79203b..46d614f4fb 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -32,6 +32,7 @@ extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
 extern void apply_tlist_labeling(List *dest_tlist, List *src_tlist);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 16b0b1d2dc..b9a9ecb7cc 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f95d165288..e8d5ef33d4 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,6 +1100,690 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+   string_to_array   
+---------------------
+ {A,B,C,D,E,F,G,H,I}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+ ?column? 
+----------
+ f
+(1 row)
+
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+ ?column? 
+----------
+ t
+(1 row)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index d33f04a3b5..6b245a7f28 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,6 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index cc3f5f3737..edd6d1ef7f 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0aeba3e202..b0e0b21d1e 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,6 +425,241 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index e882153244..4ca02b821d 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,6 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 8bca1f5d55..7e0ef0554a 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..1c5ebcd0e6
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,103 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+# Test plan: Create a table with a nondeterministic collation in the
+# primary key column.  Pre-insert rows on the publisher and subscriber
+# that are collation-wise equal but byte-wise different.  (We use a
+# string in different normal forms for that.)  Set up publisher and
+# subscriber.  Update the row on the publisher, but don't change the
+# primary key column.  The subscriber needs to find the row to be
+# updated using the nondeterministic collation semantics.  We need to
+# test for both a replica identity index and for replica identity
+# full, since those have different code paths internally.
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false)});
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text PRIMARY KEY, b text)});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text COLLATE ctest_nondet PRIMARY KEY, b text)});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\0061\0308bc', 'foo')});
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text, b text)});
+$node_publisher->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text COLLATE ctest_nondet, b text)});
+$node_subscriber->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\0061\0308bc', 'foo')});
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE PUBLICATION pub1 FOR ALL TABLES});
+
+$node_subscriber->safe_psql('postgres',
+	qq{CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr application_name=sub1' PUBLICATION pub1 WITH (copy_data = false)});
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab1 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab1}),
+   qq(bar),
+  'update with primary key with nondeterministic collation');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab2 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab2}),
+   qq(bar),
+  'update with replica identity full with nondeterministic collation');

base-commit: fa86238f1eac5b1bfb3887d2deb138f53da82c9b
-- 
2.20.1

From 48337b4076a7aaf7cc5d020515cf8b1d4e0a4b0c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Fri, 8 Mar 2019 11:03:54 +0100
Subject: [PATCH v8] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Discussion: https://www.postgresql.org/message-id/flat/1ccc668f-4cbc-0bef-af67-450b47cdfee7@2ndquadrant.com
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  61 +-
 doc/src/sgml/citext.sgml                      |  21 +
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            | 100 ++-
 src/backend/access/spgist/spgtextproc.c       |   3 +-
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/commands/extension.c              |   6 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  14 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/like_support.c          |  14 +
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  33 +-
 src/backend/utils/adt/varchar.c               | 194 ++++-
 src/backend/utils/adt/varlena.c               | 333 +++++---
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   4 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 710 ++++++++++++++++++
 .../regress/expected/collate.linux.utf8.out   |   5 +
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 250 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   7 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      | 103 +++
 68 files changed, 2086 insertions(+), 238 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index d641361aef..7c18eaa508 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 0fd792ff1a..45ed077654 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..555d1b4ac6 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,13 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>;
+    see <xref linkend="collation-nondeterministic"/>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
@@ -883,6 +885,55 @@ <title>Copying Collations</title>
    </para>
    </sect4>
    </sect3>
+
+   <sect3 id="collation-nondeterministic">
+    <title>Nondeterminstic Collations</title>
+
+    <para>
+     A collation is either <firstterm>deterministic</firstterm> or
+     <firstterm>nondeterministic</firstterm>.  A deterministic collation uses
+     deterministic comparisons, which means that it considers strings to be
+     equal only if they consist of the same byte sequence.  Nondeterministic
+     comparison may determine strings to be equal even if they consist of
+     different bytes.  Typical situations include case-insensitive comparison,
+     accent-insensitive comparison, as well as comparion of strings in
+     different Unicode normal forms.  It is up to the collation provider to
+     actually implement such insensitive comparisons; the deterministic flag
+     only determines whether ties are to be broken using bytewise comparison.
+     See also <ulink url="https://unicode.org/reports/tr10">Unicode Technical
+     Standard 10</ulink> for more information on the terminology.
+    </para>
+
+    <para>
+     To create a nondeterministic collation, specify the property
+     <literal>deterministic = false</literal> to <command>CREATE
+     COLLATION</command>, for example:
+<programlisting>
+CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
+</programlisting>
+     This example would use the standard Unicode collation in a
+     nondeterministic way.  In particular, this would allow strings in
+     different normal forms to be compared correctly.  More interesting
+     examples make use of the ICU customization facilities explained above.
+     For example:
+<programlisting>
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+</programlisting>
+    </para>
+
+    <para>
+     All standard and predefined collations are deterministic, all
+     user-defined collations are deterministic by default.  While
+     nondeterministic collations give a more <quote>correct</quote> behavior,
+     especially when considering the full power of Unicode and its many
+     special cases, they also have some drawbacks.  Foremost, their use leads
+     to a performance penalty.  Also, certain operations are not possible with
+     nondeterministic collations, such as pattern matching operations.
+     Therefore, they should be used only in cases where they are specifically
+     wanted.
+    </para>
+   </sect3>
   </sect2>
  </sect1>
 
diff --git a/doc/src/sgml/citext.sgml b/doc/src/sgml/citext.sgml
index b1fe7101b2..85aa339d8b 100644
--- a/doc/src/sgml/citext.sgml
+++ b/doc/src/sgml/citext.sgml
@@ -14,6 +14,16 @@ <title>citext</title>
   exactly like <type>text</type>.
  </para>
 
+ <tip>
+  <para>
+   Consider using <firstterm>nondeterministic collations</firstterm> (see
+   <xref linkend="collation-nondeterministic"/>) instead of this module.  They
+   can be used for case-insensitive comparisons, accent-insensitive
+   comparisons, and other combinations, and they handle more Unicode special
+   cases correctly.
+  </para>
+ </tip>
+
  <sect2>
   <title>Rationale</title>
 
@@ -246,6 +256,17 @@ <title>Limitations</title>
       will be invoked instead.
     </para>
     </listitem>
+
+    <listitem>
+     <para>
+      The approach of lower-casing strings for comparison does not handle some
+      Unicode special cases correctly, for example when one upper-case letter
+      has two lower-case letter equivalents.  Unicode distinguishes between
+      <firstterm>case mapping</firstterm> and <firstterm>case
+      folding</firstterm> for this reason.  Use nondeterministic collations
+      instead of <type>citext</type> to handle that correctly.
+     </para>
+    </listitem>
    </itemizedlist>
  </sect2>
 
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 03859a78ea..7faec35f91 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -3962,6 +3962,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index 63005ddc4d..cc116f5ece 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,7 +27,9 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -242,15 +244,51 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/*
-	 * Note: this is currently identical in behavior to hashvarlena, but keep
-	 * it as a separate function in case we someday want to do something
-	 * different in non-C locales.  (See also hashbpchar, if so.)
-	 */
-	result = hash_any((unsigned char *) VARDATA_ANY(key),
-					  VARSIZE_ANY_EXHDR(key));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -262,12 +300,52 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/* Same approach as hashtext */
-	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
-							   VARSIZE_ANY_EXHDR(key),
-							   PG_GETARG_INT64(1));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 39cd391529..d22998c54b 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -630,7 +630,8 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
 			 * query (prefix) string, so we don't need to check it again.
 			 */
 			res = (level >= queryLen) ||
-				DatumGetBool(DirectFunctionCall2(text_starts_with,
+				DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
+													 PG_GET_COLLATION(),
 												 out->leafValue,
 												 PointerGetDatum(query)));
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..d4723fced8 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -901,7 +901,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		{
 			const char *qSchemaName = quote_identifier(schemaName);
 
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("@extschema@"),
 										CStringGetTextDatum(qSchemaName));
@@ -913,7 +914,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		 */
 		if (control->module_pathname)
 		{
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("MODULE_PATHNAME"),
 										CStringGetTextDatum(control->module_pathname));
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 7cbf9d3bc1..0fb31f5c3d 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3317,6 +3317,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3377,6 +3378,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3394,7 +3396,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index a9d80e692b..870a730a66 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -61,6 +61,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -76,7 +77,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -156,6 +157,7 @@ BuildTupleHashTableExt(PlanState *parent,
 					   int numCols, AttrNumber *keyColIdx,
 					   const Oid *eqfuncoids,
 					   FmgrInfo *hashfunctions,
+					   Oid *collations,
 					   long nbuckets, Size additionalsize,
 					   MemoryContext metacxt,
 					   MemoryContext tablecxt,
@@ -178,6 +180,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -213,7 +216,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													NULL);
 
 	/*
@@ -241,6 +244,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt,
@@ -251,6 +255,7 @@ BuildTupleHashTable(PlanState *parent,
 								  numCols, keyColIdx,
 								  eqfuncoids,
 								  hashfunctions,
+								  collations,
 								  nbuckets, additionalsize,
 								  tablecxt,
 								  tablecxt,
@@ -422,8 +427,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index aaa81f0620..7b3ad97ff5 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1249,6 +1249,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 5c5aa96e7f..a964522fdd 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -95,6 +95,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -261,7 +263,8 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										values[attrnum],
 										slot->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index bae7989a42..47161afbd4 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -746,15 +746,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1287,6 +1286,7 @@ build_hash_table(AggState *aggstate)
 														perhash->hashGrpColIdxHash,
 														perhash->eqfuncoids,
 														perhash->hashfunctions,
+														perhash->aggnode->grpCollations,
 														perhash->aggnode->numGroups,
 														additionalsize,
 														aggstate->ss.ps.state->es_query_cxt,
@@ -2381,6 +2381,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2392,6 +2393,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3155,6 +3157,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 9b74ed3208..9c5eed7def 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 												node->dupColIdx,
 												rustate->eqfuncoids,
 												rustate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												rustate->ps.state->es_query_cxt,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 26aeaee083..044246aa09 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												   node->dupColIdx,
 												   setopstate->eqfuncoids,
 												   setopstate->hashfunctions,
+												   node->dupCollations,
 												   node->numGroups,
 												   0,
 												   setopstate->ps.state->es_query_cxt,
@@ -554,6 +555,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index d7d076758c..749b4eced3 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -514,6 +514,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 												 node->keyColIdx,
 												 node->tab_eq_funcoids,
 												 node->tab_hash_funcs,
+												 node->tab_collations,
 												 nbuckets,
 												 0,
 												 node->planstate->state->es_query_cxt,
@@ -541,6 +542,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 													 node->keyColIdx,
 													 node->tab_eq_funcoids,
 													 node->tab_hash_funcs,
+													 node->tab_collations,
 													 nbuckets,
 													 0,
 													 node->planstate->state->es_query_cxt,
@@ -642,6 +644,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -679,8 +682,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -722,6 +725,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -817,6 +821,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -915,6 +920,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -965,6 +971,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -1001,6 +1010,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 157ac042b8..b090828c01 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index a8a735c247..d6fe35374b 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 69179a07c3..910a738c20 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 4b845b1bb7..eff98febf1 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1677,6 +1677,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2143,6 +2144,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2162,6 +2164,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2184,9 +2187,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2212,6 +2217,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2290,6 +2296,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 9fbe5b2a5f..93c56c657c 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -260,14 +260,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1387,6 +1387,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1453,6 +1454,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1463,7 +1465,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1501,6 +1505,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1883,6 +1888,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1949,6 +1956,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2110,6 +2119,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2147,6 +2157,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2246,9 +2257,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2270,6 +2283,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2280,11 +2294,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2295,6 +2311,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2304,9 +2321,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5326,10 +5345,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5339,11 +5360,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6015,7 +6038,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6031,6 +6054,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6046,8 +6070,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6060,9 +6084,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6087,6 +6113,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6095,6 +6122,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6118,6 +6146,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6132,6 +6161,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6140,6 +6170,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6147,6 +6178,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6162,6 +6194,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6177,6 +6210,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6245,6 +6279,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6252,6 +6287,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6296,6 +6332,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6309,6 +6346,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6317,6 +6355,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6326,6 +6365,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 14d1c67a94..bb3b7969f2 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -503,6 +503,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index e71eb3793b..83abff94bd 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2659,7 +2659,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2680,7 +2680,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index b5c0889935..31e0164ea9 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2159,6 +2159,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2179,7 +2180,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 5b2917d159..61deefbbc8 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3958,7 +3958,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(*locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 853c9c01e9..704e5720cf 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(const char *t, int tlen, const char *p, int plen,
 static int SB_IMatchText(const char *t, int tlen, const char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(const char *s, int slen, const char *p, int plen);
+static int	GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(const char *s, int slen, const char *p, int plen)
+GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
 {
+	if (collation && !lc_ctype_is_c(collation) && collation != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index 69509811ef..a65e63736c 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -257,6 +257,20 @@ match_pattern_prefix(Node *leftop,
 		return NIL;
 	patt = (Const *) rightop;
 
+	/*
+	 * Not supported if the expression collation is nondeterministic.  The
+	 * optimized equality or prefix tests use bytewise comparisons, which is
+	 * not consistent with nondeterministic collations.  The actual
+	 * pattern-matching implementation functions will later error out that
+	 * pattern-matching is not supported with nondeterministic collations.
+	 * (We could also error out here, but by doing it later we get more
+	 * precise error messages.)  (It should be possible to support at least
+	 * Pattern_Prefix_Exact, but no point as along as the actual
+	 * pattern-matching implementations don't support it.)
+	 */
+	if (!get_collation_isdeterministic(expr_coll))
+		return NIL;
+
 	/*
 	 * Try to extract a fixed prefix from the pattern.
 	 */
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 2d384a9944..4db2d0d0e1 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..1f7fdc0593 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1308,6 +1308,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index ef04fa5009..f98db135ad 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -692,6 +692,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -700,6 +702,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = "AND";
 			queryoids[i] = pk_type;
 		}
@@ -794,6 +798,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -802,6 +808,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = "AND";
 			queryoids[i] = pk_type;
 		}
@@ -906,6 +914,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -917,6 +927,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = ",";
 			qualsep = "AND";
 			queryoids[i] = pk_type;
@@ -1081,6 +1093,8 @@ ri_set(TriggerData *trigdata, bool is_set_null)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1093,6 +1107,8 @@ ri_set(TriggerData *trigdata, bool is_set_null)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = ",";
 			qualsep = "AND";
 			queryoids[i] = pk_type;
@@ -2492,11 +2508,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
 	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /*
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index c866af022f..447d57b3a1 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -24,6 +24,8 @@
 #include "nodes/supportnodes.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/lsyscache.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -718,6 +720,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -726,18 +744,31 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = false;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = false;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -753,18 +784,29 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = true;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = true;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -934,23 +976,60 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 /*
  * bpchar needs a specialized hash function because we want to ignore
  * trailing blanks in comparisons.
- *
- * Note: currently there is no need for locale-specific behavior here,
- * but if we ever change the semantics of bpchar comparison to trust
- * strcoll() completely, we'd need to do something different in non-C locales.
  */
 Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any((unsigned char *) keydata, keylen);
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) keydata, keylen);
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -962,15 +1041,56 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any_extended((unsigned char *) keydata, keylen,
-							   PG_GETARG_INT64(1));
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) keydata, keylen,
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
@@ -986,12 +1106,23 @@ hashbpcharextended(PG_FUNCTION_ARGS)
  */
 
 static int
-internal_bpchar_pattern_compare(BpChar *arg1, BpChar *arg2)
+internal_bpchar_pattern_compare(BpChar *arg1, BpChar *arg2, Oid collid)
 {
 	int			result;
 	int			len1,
 				len2;
 
+	check_collation_set(collid);
+
+	/*
+	 * see internal_text_pattern_compare()
+	 */
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"bpchar_pattern_ops")));
+
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
@@ -1014,7 +1145,7 @@ bpchar_pattern_lt(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1030,7 +1161,7 @@ bpchar_pattern_le(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1046,7 +1177,7 @@ bpchar_pattern_ge(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1062,7 +1193,7 @@ bpchar_pattern_gt(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1078,7 +1209,7 @@ btbpchar_pattern_cmp(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1091,8 +1222,17 @@ Datum
 btbpchar_pattern_sortsupport(PG_FUNCTION_ARGS)
 {
 	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
+	Oid			collid = ssup->ssup_collation;
 	MemoryContext oldcontext;
 
+	check_collation_set(collid);
+
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"bpchar_pattern_ops")));
+
 	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
 
 	/* Use generic string SortSupport, forcing "C" collation */
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 693ccc5149..9f810c2fd5 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -122,13 +122,14 @@ static text *text_substring(Datum str,
 			   int32 length,
 			   bool length_not_specified);
 static text *text_overlay(text *t1, text *t2, int sp, int sl);
-static int	text_position(text *t1, text *t2);
-static void text_position_setup(text *t1, text *t2, TextPositionState *state);
+static int	text_position(text *t1, text *t2, Oid collid);
+static void text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state);
 static bool text_position_next(TextPositionState *state);
 static char *text_position_next_internal(char *start_ptr, TextPositionState *state);
 static char *text_position_get_match_ptr(TextPositionState *state);
 static int	text_position_get_match_pos(TextPositionState *state);
 static void text_position_cleanup(TextPositionState *state);
+static void check_collation_set(Oid collid);
 static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static bytea *bytea_catenate(bytea *t1, bytea *t2);
 static bytea *bytea_substring(Datum str,
@@ -1094,7 +1095,7 @@ textpos(PG_FUNCTION_ARGS)
 	text	   *str = PG_GETARG_TEXT_PP(0);
 	text	   *search_str = PG_GETARG_TEXT_PP(1);
 
-	PG_RETURN_INT32((int32) text_position(str, search_str));
+	PG_RETURN_INT32((int32) text_position(str, search_str, PG_GET_COLLATION()));
 }
 
 /*
@@ -1112,7 +1113,7 @@ textpos(PG_FUNCTION_ARGS)
  *	functions.
  */
 static int
-text_position(text *t1, text *t2)
+text_position(text *t1, text *t2, Oid collid)
 {
 	TextPositionState state;
 	int			result;
@@ -1120,7 +1121,7 @@ text_position(text *t1, text *t2)
 	if (VARSIZE_ANY_EXHDR(t1) < 1 || VARSIZE_ANY_EXHDR(t2) < 1)
 		return 0;
 
-	text_position_setup(t1, t2, &state);
+	text_position_setup(t1, t2, collid, &state);
 	if (!text_position_next(&state))
 		result = 0;
 	else
@@ -1147,10 +1148,21 @@ text_position(text *t1, text *t2)
  */
 
 static void
-text_position_setup(text *t1, text *t2, TextPositionState *state)
+text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
+	pg_locale_t	mylocale = 0;
+
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
 
 	Assert(len1 > 0);
 	Assert(len2 > 0);
@@ -1429,6 +1441,22 @@ text_position_cleanup(TextPositionState *state)
 	/* no cleanup needed */
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1441,6 +1469,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1462,20 +1492,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1558,13 +1575,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 				ereport(ERROR,
 						(errmsg("could not compare Unicode strings: %m")));
 
-			/*
-			 * In some locales wcscoll() can claim that nonidentical strings
-			 * are equal.  Believing that would be bad news for a number of
-			 * reasons, so we follow Perl's lead and sort "equal" strings
-			 * according to strcmp (on the UTF-8 representation).
-			 */
-			if (result == 0)
+			/* Break tie if necessary. */
+			if (result == 0 &&
+				(!mylocale || mylocale->deterministic))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1649,13 +1662,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		else
 			result = strcoll(a1p, a2p);
 
-		/*
-		 * In some locales strcoll() can claim that nonidentical strings are
-		 * equal.  Believing that would be bad news for a number of reasons,
-		 * so we follow Perl's lead and sort "equal" strings according to
-		 * strcmp().
-		 */
-		if (result == 0)
+		/* Break tie if necessary. */
+		if (result == 0 &&
+			(!mylocale || mylocale->deterministic))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1699,33 +1708,52 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
-	 * don't even have to do a bitwise comparison if we can show the lengths
-	 * of the strings are unequal; which might save us from having to detoast
-	 * one or both values.
-	 */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = false;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
+		 * don't even have to do a bitwise comparison if we can show the lengths
+		 * of the strings are unequal; which might save us from having to detoast
+		 * one or both values.
+		 */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = false;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) == 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) == 0);
+		result = (text_cmp(arg1, arg2, collid) == 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1734,27 +1762,46 @@ texteq(PG_FUNCTION_ARGS)
 Datum
 textne(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/* See comment in texteq() */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = true;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/* See comment in texteq() */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = true;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) != 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) != 0);
+		result = (text_cmp(arg1, arg2, collid) != 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1825,10 +1872,22 @@ text_starts_with(PG_FUNCTION_ARGS)
 {
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	bool		result;
 	Size		len1,
 				len2;
 
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
+
 	len1 = toast_raw_datum_size(arg1);
 	len2 = toast_raw_datum_size(arg2);
 	if (len2 > len1)
@@ -1898,6 +1957,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1934,20 +1995,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2328,12 +2376,9 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	else
 		result = strcoll(sss->buf1, sss->buf2);
 
-	/*
-	 * In some locales strcoll() can claim that nonidentical strings are
-	 * equal. Believing that would be bad news for a number of reasons, so we
-	 * follow Perl's lead and sort "equal" strings according to strcmp().
-	 */
-	if (result == 0)
+	/* Break tie if necessary. */
+	if (result == 0 &&
+		(!sss->locale || sss->locale->deterministic))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2760,10 +2805,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2777,10 +2830,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2794,10 +2855,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2811,10 +2880,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2919,12 +2996,34 @@ textgename(PG_FUNCTION_ARGS)
  */
 
 static int
-internal_text_pattern_compare(text *arg1, text *arg2)
+internal_text_pattern_compare(text *arg1, text *arg2, Oid collid)
 {
 	int			result;
 	int			len1,
 				len2;
 
+	check_collation_set(collid);
+
+	/*
+	 * XXX We cannot use a text_pattern_ops index for nondeterministic
+	 * collations, because these operators intentionally ignore the collation.
+	 * However, the planner has no way to know that, so it might choose such
+	 * an index for an "=" clause, which would lead to wrong results.  This
+	 * check here doesn't prevent choosing the index, but it will at least
+	 * error out if the index is chosen.  A text_pattern_ops index on a column
+	 * with nondeterministic collation is pretty useless anyway, since LIKE
+	 * etc. won't work there either.  A future possibility would be to
+	 * annotate the operator class or its members in the catalog to avoid the
+	 * index.  Another alternative is to stay away from the *_pattern_ops
+	 * operator classes and prefer creating LIKE-supporting indexes with
+	 * COLLATE "C".
+	 */
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"text_pattern_ops")));
+
 	len1 = VARSIZE_ANY_EXHDR(arg1);
 	len2 = VARSIZE_ANY_EXHDR(arg2);
 
@@ -2947,7 +3046,7 @@ text_pattern_lt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2963,7 +3062,7 @@ text_pattern_le(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2979,7 +3078,7 @@ text_pattern_ge(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2995,7 +3094,7 @@ text_pattern_gt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3011,7 +3110,7 @@ bttext_pattern_cmp(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3024,8 +3123,17 @@ Datum
 bttext_pattern_sortsupport(PG_FUNCTION_ARGS)
 {
 	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
+	Oid			collid = ssup->ssup_collation;
 	MemoryContext oldcontext;
 
+	check_collation_set(collid);
+
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"text_pattern_ops")));
+
 	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
 
 	/* Use generic string SortSupport, forcing "C" collation */
@@ -4121,7 +4229,7 @@ replace_text(PG_FUNCTION_ARGS)
 		PG_RETURN_TEXT_P(src_text);
 	}
 
-	text_position_setup(src_text, from_sub_text, &state);
+	text_position_setup(src_text, from_sub_text, PG_GET_COLLATION(), &state);
 
 	found = text_position_next(&state);
 
@@ -4482,7 +4590,7 @@ split_text(PG_FUNCTION_ARGS)
 			PG_RETURN_TEXT_P(cstring_to_text(""));
 	}
 
-	text_position_setup(inputstring, fldsep, &state);
+	text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 	/* identify bounds of first field */
 	start_ptr = VARDATA_ANY(inputstring);
@@ -4538,11 +4646,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4633,7 +4742,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 			int			lbs[1];
 
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4645,7 +4754,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 													 TEXTOID, -1, false, 'i'));
 		}
 
-		text_position_setup(inputstring, fldsep, &state);
+		text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 		start_ptr = VARDATA_ANY(inputstring);
 
@@ -4673,7 +4782,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4715,7 +4824,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 78dd5714fa..bb9ae8fd0c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -171,13 +171,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e88c45d268..59e6bcd856 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e962ae7e91..31ef4eea12 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13406,6 +13406,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13423,28 +13424,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13471,6 +13479,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 779e48437c..fd8ebee8cd 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4106,7 +4106,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4134,6 +4134,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 9003f2ce58..0cf7aa3495 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -129,6 +131,7 @@ extern TupleHashTable BuildTupleHashTableExt(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext metacxt,
 					MemoryContext tablecxt,
@@ -257,6 +260,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index fd13c170d7..d3ed5077ec 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -693,6 +693,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -862,6 +863,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1872,6 +1874,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index d66a187a53..24740c31e3 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 3bbdb5e2f7..b093a3c8ac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -53,7 +53,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 58db79203b..46d614f4fb 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -32,6 +32,7 @@ extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
 extern void apply_tlist_labeling(List *dest_tlist, List *src_tlist);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 16b0b1d2dc..b9a9ecb7cc 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f95d165288..fc8f092585 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,6 +1100,716 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+   string_to_array   
+---------------------
+ {A,B,C,D,E,F,G,H,I}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+CREATE INDEX ON test3ci (x text_pattern_ops);  -- error
+ERROR:  nondeterministic collations are not supported for operator class "text_pattern_ops"
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+CREATE INDEX ON test3bpci (x bpchar_pattern_ops);  -- error
+ERROR:  nondeterministic collations are not supported for operator class "bpchar_pattern_ops"
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- This tests the issue described in match_pattern_prefix().  In the
+-- absence of that check, the case_insensitive tests below would
+-- return no rows where they should logically return one.
+CREATE TABLE test4c (x text COLLATE "C");
+INSERT INTO test4c VALUES ('abc');
+CREATE INDEX ON test4c (x);
+SET enable_seqscan = off;
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_sensitive;  -- ok, no rows
+ x 
+---
+(0 rows)
+
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_sensitive;  -- ok, no rows
+ x 
+---
+(0 rows)
+
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_insensitive;  -- error
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_insensitive;  -- error
+ERROR:  nondeterministic collations are not supported for LIKE
+RESET enable_seqscan;
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+ ?column? 
+----------
+ f
+(1 row)
+
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+ ?column? 
+----------
+ t
+(1 row)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index d33f04a3b5..6b245a7f28 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,6 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index fe5fc64480..4a54104182 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0aeba3e202..8de4ad7b5d 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,6 +425,256 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+CREATE INDEX ON test3ci (x text_pattern_ops);  -- error
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+CREATE INDEX ON test3bpci (x bpchar_pattern_ops);  -- error
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+
+-- This tests the issue described in match_pattern_prefix().  In the
+-- absence of that check, the case_insensitive tests below would
+-- return no rows where they should logically return one.
+CREATE TABLE test4c (x text COLLATE "C");
+INSERT INTO test4c VALUES ('abc');
+CREATE INDEX ON test4c (x);
+SET enable_seqscan = off;
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_sensitive;  -- ok, no rows
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_sensitive;  -- ok, no rows
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_insensitive;  -- error
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_insensitive;  -- error
+RESET enable_seqscan;
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index e882153244..4ca02b821d 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,6 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index b5931ee700..856bbff732 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..1c5ebcd0e6
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,103 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+# Test plan: Create a table with a nondeterministic collation in the
+# primary key column.  Pre-insert rows on the publisher and subscriber
+# that are collation-wise equal but byte-wise different.  (We use a
+# string in different normal forms for that.)  Set up publisher and
+# subscriber.  Update the row on the publisher, but don't change the
+# primary key column.  The subscriber needs to find the row to be
+# updated using the nondeterministic collation semantics.  We need to
+# test for both a replica identity index and for replica identity
+# full, since those have different code paths internally.
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false)});
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text PRIMARY KEY, b text)});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text COLLATE ctest_nondet PRIMARY KEY, b text)});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\0061\0308bc', 'foo')});
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text, b text)});
+$node_publisher->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text COLLATE ctest_nondet, b text)});
+$node_subscriber->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\0061\0308bc', 'foo')});
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE PUBLICATION pub1 FOR ALL TABLES});
+
+$node_subscriber->safe_psql('postgres',
+	qq{CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr application_name=sub1' PUBLICATION pub1 WITH (copy_data = false)});
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab1 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab1}),
+   qq(bar),
+  'update with primary key with nondeterministic collation');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab2 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab2}),
+   qq(bar),
+  'update with replica identity full with nondeterministic collation');

base-commit: e1e0e8d58c5c70da92e36cb9d59c2f7ecf839e00
-- 
2.21.0

From dc21791adee43a854247ff007b3757ab480e509d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 11 Mar 2019 16:10:59 +0100
Subject: [PATCH 1/2] Add tests for ICU collation customization

---
 .../regress/expected/collate.icu.utf8.out     | 39 +++++++++++++++++++
 src/test/regress/sql/collate.icu.utf8.sql     | 21 ++++++++++
 2 files changed, 60 insertions(+)

diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index f95d165288..4b94921cf8 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1100,6 +1100,45 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- test ICU collation customization
+CREATE COLLATION testcoll_ignore_accents (provider = icu, locale = '@colStrength=primary;colCaseLevel=yes');
+SELECT 'aaá' > 'AAA' COLLATE "und-x-icu", 'aaá' < 'AAA' COLLATE testcoll_ignore_accents;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE COLLATION testcoll_backwards (provider = icu, locale = '@colBackwards=yes');
+SELECT 'coté' < 'côte' COLLATE "und-x-icu", 'coté' > 'côte' COLLATE testcoll_backwards;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE COLLATION testcoll_lower_first (provider = icu, locale = '@colCaseFirst=lower');
+CREATE COLLATION testcoll_upper_first (provider = icu, locale = '@colCaseFirst=upper');
+SELECT 'aaa' < 'AAA' COLLATE testcoll_lower_first, 'aaa' > 'AAA' COLLATE testcoll_upper_first;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE COLLATION testcoll_shifted (provider = icu, locale = '@colAlternate=shifted');
+SELECT 'de-luge' < 'deanza' COLLATE "und-x-icu", 'de-luge' > 'deanza' COLLATE testcoll_shifted;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE COLLATION testcoll_numeric (provider = icu, locale = '@colNumeric=yes');
+SELECT 'A-21' > 'A-123' COLLATE "und-x-icu", 'A-21' < 'A-123' COLLATE testcoll_numeric;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
+ERROR:  could not open collator for locale "@colNumeric=lower": U_ILLEGAL_ARGUMENT_ERROR
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 0aeba3e202..73fb1232a7 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -425,6 +425,27 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- test ICU collation customization
+
+CREATE COLLATION testcoll_ignore_accents (provider = icu, locale = '@colStrength=primary;colCaseLevel=yes');
+SELECT 'aaá' > 'AAA' COLLATE "und-x-icu", 'aaá' < 'AAA' COLLATE testcoll_ignore_accents;
+
+CREATE COLLATION testcoll_backwards (provider = icu, locale = '@colBackwards=yes');
+SELECT 'coté' < 'côte' COLLATE "und-x-icu", 'coté' > 'côte' COLLATE testcoll_backwards;
+
+CREATE COLLATION testcoll_lower_first (provider = icu, locale = '@colCaseFirst=lower');
+CREATE COLLATION testcoll_upper_first (provider = icu, locale = '@colCaseFirst=upper');
+SELECT 'aaa' < 'AAA' COLLATE testcoll_lower_first, 'aaa' > 'AAA' COLLATE testcoll_upper_first;
+
+CREATE COLLATION testcoll_shifted (provider = icu, locale = '@colAlternate=shifted');
+SELECT 'de-luge' < 'deanza' COLLATE "und-x-icu", 'de-luge' > 'deanza' COLLATE testcoll_shifted;
+
+CREATE COLLATION testcoll_numeric (provider = icu, locale = '@colNumeric=yes');
+SELECT 'A-21' > 'A-123' COLLATE "und-x-icu", 'A-21' < 'A-123' COLLATE testcoll_numeric;
+
+CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
-- 
2.21.0

From 711ec5f45e83abab93d06cc1d65647d04c6e97d0 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 11 Mar 2019 21:20:03 +0100
Subject: [PATCH 2/2] Add support for collation attributes on older ICU
 versions

Starting in ICU 54, collation customization attributes can be
specified in the locale string, for example
"@colStrength=primary;colCaseLevel=yes".  Add support for this for
older ICU versions as well, by adding some minimal parsing of the
attributes in the locale string and calling ucol_setAttribute() on
them.  This is essentially what never ICU versions do internally in
ucol_open().  This was we can offer this functionality in a consistent
way in all ICU versions supported by PostgreSQL.
---
 src/backend/utils/adt/pg_locale.c | 104 ++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 50b8b31645..c6fedab8f4 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -58,6 +58,7 @@
 #include "catalog/pg_control.h"
 #include "mb/pg_wchar.h"
 #include "utils/builtins.h"
+#include "utils/formatting.h"
 #include "utils/hsearch.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
@@ -132,6 +133,9 @@ static HTAB *collation_cache = NULL;
 static char *IsoLocaleName(const char *);	/* MSVC specific */
 #endif
 
+#ifdef USE_ICU
+static void icu_set_collation_attributes(UCollator *collator, const char *loc);
+#endif
 
 /*
  * pg_perm_setlocale
@@ -1380,6 +1384,9 @@ pg_newlocale_from_collation(Oid collid)
 						(errmsg("could not open collator for locale \"%s\": %s",
 								collcollate, u_errorName(status))));
 
+			if (U_ICU_VERSION_MAJOR_NUM < 54)
+				icu_set_collation_attributes(collator, collcollate);
+
 			/* We will leak this string if we get an error below :-( */
 			result.info.icu.locale = MemoryContextStrdup(TopMemoryContext,
 														 collcollate);
@@ -1588,6 +1595,103 @@ icu_from_uchar(char **result, const UChar *buff_uchar, int32_t len_uchar)
 	return len_result;
 }
 
+/*
+ * Parse collation attributes and apply them to the open collator.  This takes
+ * a string like "und@colStrength=primary;colCaseLevel=yes" and parses and
+ * applyes the key-value arguments.
+ *
+ * Starting with ICU version 54, the attributes are processed automatically by
+ * ucol_open(), so this is only necessary for emulating this behavior on older
+ * versions.
+ */
+pg_attribute_unused()
+static void
+icu_set_collation_attributes(UCollator *collator, const char *loc)
+{
+	char	   *str = asc_tolower(loc, strlen(loc));
+
+	str = strchr(str, '@');
+	if (!str)
+		return;
+	str++;
+
+	for (char *token = strtok(str, ";"); token; token = strtok(NULL, ";"))
+	{
+		char	   *e = strchr(token, '=');
+
+		if (e)
+		{
+			char	   *name;
+			char	   *value;
+			UColAttribute uattr = -1;
+			UColAttributeValue uvalue = -1;
+			UErrorCode	status;
+
+			status = U_ZERO_ERROR;
+
+			*e = '\0';
+			name = token;
+			value = e + 1;
+
+			/*
+			 * See attribute name and value lists in ICU i18n/coll.cpp
+			 */
+			if (strcmp(name, "colstrength") == 0)
+				uattr = UCOL_STRENGTH;
+			else if (strcmp(name, "colbackwards") == 0)
+				uattr = UCOL_FRENCH_COLLATION;
+			else if (strcmp(name, "colcaselevel") == 0)
+				uattr = UCOL_CASE_LEVEL;
+			else if (strcmp(name, "colcasefirst") == 0)
+				uattr = UCOL_CASE_FIRST;
+			else if (strcmp(name, "colalternate") == 0)
+				uattr = UCOL_ALTERNATE_HANDLING;
+			else if (strcmp(name, "colnormalization") == 0)
+				uattr = UCOL_NORMALIZATION_MODE;
+			else if (strcmp(name, "colnumeric") == 0)
+				uattr = UCOL_NUMERIC_COLLATION;
+			/* ignore if unknown */
+
+			if (strcmp(value, "primary") == 0)
+				uvalue = UCOL_PRIMARY;
+			else if (strcmp(value, "secondary") == 0)
+				uvalue = UCOL_SECONDARY;
+			else if (strcmp(value, "tertiary") == 0)
+				uvalue = UCOL_TERTIARY;
+			else if (strcmp(value, "quaternary") == 0)
+				uvalue = UCOL_QUATERNARY;
+			else if (strcmp(value, "identical") == 0)
+				uvalue = UCOL_IDENTICAL;
+			else if (strcmp(value, "no") == 0)
+				uvalue = UCOL_OFF;
+			else if (strcmp(value, "yes") == 0)
+				uvalue = UCOL_ON;
+			else if (strcmp(value, "shifted") == 0)
+				uvalue = UCOL_SHIFTED;
+			else if (strcmp(value, "non-ignorable") == 0)
+				uvalue = UCOL_NON_IGNORABLE;
+			else if (strcmp(value, "lower") == 0)
+				uvalue = UCOL_LOWER_FIRST;
+			else if (strcmp(value, "upper") == 0)
+				uvalue = UCOL_UPPER_FIRST;
+			else
+				status = U_ILLEGAL_ARGUMENT_ERROR;
+
+			if (uattr != -1 && uvalue != -1)
+				ucol_setAttribute(collator, uattr, uvalue, &status);
+
+			/*
+			 * Pretend the error came from ucol_open(), for consistent error
+			 * message across ICU versions.
+			 */
+			if (U_FAILURE(status))
+				ereport(ERROR,
+						(errmsg("could not open collator for locale \"%s\": %s",
+								loc, u_errorName(status))));
+		}
+	}
+}
+
 #endif							/* USE_ICU */
 
 /*
-- 
2.21.0

From 42f7c14e549a442eeff054c3f9eca26c17f4915e Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 18 Mar 2019 00:12:52 +0100
Subject: [PATCH v9] Collations with nondeterministic comparison

This adds a flag "deterministic" to collations.  If that is false,
such a collation disables various optimizations that assume that
strings are equal only if they are byte-wise equal.  That then allows
use cases such as case-insensitive or accent-insensitive comparisons
or handling of strings with different Unicode normal forms.

The term "deterministic comparison" in this context is from Unicode
Technical Standard #10
(https://unicode.org/reports/tr10/#Deterministic_Comparison).

This patch makes changes in three areas:

- CREATE COLLATION DDL changes and system catalog changes to support
  this new flag.

- Many executor nodes and auxiliary code are extended to track
  collations.  Previously, this code would just throw away collation
  information, because the eventually-called user-defined functions
  didn't use it since they only cared about equality, which didn't
  need collation information.

- String data type functions that do equality comparisons and hashing
  are changed to take the (non-)deterministic flag into account.  For
  comparison, this just means skipping various shortcuts and tie
  breakers that use byte-wise comparison.  For hashing, we first need
  to convert the input string to a canonical "sort key" using the ICU
  analogue of strxfrm().

Discussion: https://www.postgresql.org/message-id/flat/1ccc668f-4cbc-0bef-af67-450b47cdfee7@2ndquadrant.com
---
 contrib/bloom/bloom.h                         |   1 +
 contrib/bloom/blutils.c                       |   3 +-
 doc/src/sgml/catalogs.sgml                    |   7 +
 doc/src/sgml/charset.sgml                     |  61 +-
 doc/src/sgml/citext.sgml                      |  21 +
 doc/src/sgml/func.sgml                        |   6 +
 doc/src/sgml/ref/create_collation.sgml        |  22 +
 src/backend/access/hash/hashfunc.c            | 100 ++-
 src/backend/access/spgist/spgtextproc.c       |   3 +-
 src/backend/catalog/pg_collation.c            |   2 +
 src/backend/commands/collationcmds.c          |  25 +-
 src/backend/commands/extension.c              |   6 +-
 src/backend/executor/execExpr.c               |   4 +-
 src/backend/executor/execGrouping.c           |  14 +-
 src/backend/executor/execPartition.c          |   1 +
 src/backend/executor/execReplication.c        |   5 +-
 src/backend/executor/nodeAgg.c                |   9 +-
 src/backend/executor/nodeGroup.c              |   1 +
 src/backend/executor/nodeHash.c               |  14 +-
 src/backend/executor/nodeHashjoin.c           |   5 +
 src/backend/executor/nodeRecursiveunion.c     |   1 +
 src/backend/executor/nodeSetOp.c              |   2 +
 src/backend/executor/nodeSubplan.c            |  14 +-
 src/backend/executor/nodeUnique.c             |   1 +
 src/backend/executor/nodeWindowAgg.c          |   2 +
 src/backend/nodes/copyfuncs.c                 |   7 +
 src/backend/nodes/outfuncs.c                  |   7 +
 src/backend/nodes/readfuncs.c                 |   7 +
 src/backend/optimizer/plan/createplan.c       |  54 +-
 src/backend/optimizer/util/tlist.c            |  25 +
 src/backend/partitioning/partbounds.c         |   4 +-
 src/backend/partitioning/partprune.c          |   3 +-
 src/backend/regex/regc_pg_locale.c            |   5 +
 src/backend/utils/adt/arrayfuncs.c            |   2 +-
 src/backend/utils/adt/like.c                  |  27 +-
 src/backend/utils/adt/like_support.c          |  14 +
 src/backend/utils/adt/name.c                  |  32 +-
 src/backend/utils/adt/orderedsetaggs.c        |   3 +-
 src/backend/utils/adt/pg_locale.c             |   1 +
 src/backend/utils/adt/ri_triggers.c           |  33 +-
 src/backend/utils/adt/varchar.c               | 194 ++++-
 src/backend/utils/adt/varlena.c               | 333 +++++---
 src/backend/utils/cache/catcache.c            |   9 +-
 src/backend/utils/cache/lsyscache.c           |  16 +
 src/bin/initdb/initdb.c                       |   4 +-
 src/bin/pg_dump/pg_dump.c                     |  39 +-
 src/bin/psql/describe.c                       |  17 +-
 src/include/catalog/pg_collation.h            |   2 +
 src/include/executor/executor.h               |   4 +
 src/include/executor/hashjoin.h               |   1 +
 src/include/executor/nodeHash.h               |   2 +-
 src/include/nodes/execnodes.h                 |   3 +
 src/include/nodes/plannodes.h                 |   7 +
 src/include/optimizer/planmain.h              |   2 +-
 src/include/optimizer/tlist.h                 |   1 +
 src/include/partitioning/partbounds.h         |   1 +
 src/include/utils/lsyscache.h                 |   1 +
 src/include/utils/pg_locale.h                 |   1 +
 .../regress/expected/collate.icu.utf8.out     | 710 ++++++++++++++++++
 .../regress/expected/collate.linux.utf8.out   |   5 +
 src/test/regress/expected/collate.out         |  15 +
 src/test/regress/expected/subselect.out       |  19 +
 src/test/regress/sql/collate.icu.utf8.sql     | 250 ++++++
 src/test/regress/sql/collate.linux.utf8.sql   |   7 +
 src/test/regress/sql/collate.sql              |   5 +
 src/test/regress/sql/subselect.sql            |  17 +
 src/test/subscription/Makefile                |   2 +
 src/test/subscription/t/012_collation.pl      | 103 +++
 68 files changed, 2086 insertions(+), 238 deletions(-)
 create mode 100644 src/test/subscription/t/012_collation.pl

diff --git a/contrib/bloom/bloom.h b/contrib/bloom/bloom.h
index d641361aef..7c18eaa508 100644
--- a/contrib/bloom/bloom.h
+++ b/contrib/bloom/bloom.h
@@ -137,6 +137,7 @@ typedef struct BloomMetaPageData
 typedef struct BloomState
 {
 	FmgrInfo	hashFn[INDEX_MAX_KEYS];
+	Oid			collations[INDEX_MAX_KEYS];
 	BloomOptions opts;			/* copy of options on index's metapage */
 	int32		nColumns;
 
diff --git a/contrib/bloom/blutils.c b/contrib/bloom/blutils.c
index 6458376578..d078dfbd46 100644
--- a/contrib/bloom/blutils.c
+++ b/contrib/bloom/blutils.c
@@ -163,6 +163,7 @@ initBloomState(BloomState *state, Relation index)
 		fmgr_info_copy(&(state->hashFn[i]),
 					   index_getprocinfo(index, i + 1, BLOOM_HASH_PROC),
 					   CurrentMemoryContext);
+		state->collations[i] = index->rd_indcollation[i];
 	}
 
 	/* Initialize amcache if needed with options from metapage */
@@ -267,7 +268,7 @@ signValue(BloomState *state, BloomSignatureWord *sign, Datum value, int attno)
 	 * different columns will be mapped into different bits because of step
 	 * above
 	 */
-	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
+	hashVal = DatumGetInt32(FunctionCall1Coll(&state->hashFn[attno], state->collations[attno], value));
 	mySrand(hashVal ^ myRand());
 
 	for (j = 0; j < state->opts.bitSize[attno]; j++)
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 0fd792ff1a..45ed077654 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -2077,6 +2077,13 @@ <title><structname>pg_collation</structname> Columns</title>
        default, <literal>c</literal> = libc, <literal>i</literal> = icu</entry>
      </row>
 
+     <row>
+      <entry><structfield>collisdeterministic</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>Is the collation deterministic?</entry>
+     </row>
+
      <row>
       <entry><structfield>collencoding</structfield></entry>
       <entry><type>int4</type></entry>
diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index a6143ef8a7..555d1b4ac6 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -847,11 +847,13 @@ <title>ICU collations</title>
 
    <para>
     Note that while this system allows creating collations that <quote>ignore
-    case</quote> or <quote>ignore accents</quote> or similar (using
-    the <literal>ks</literal> key), PostgreSQL does not at the moment allow
-    such collations to act in a truly case- or accent-insensitive manner.  Any
-    strings that compare equal according to the collation but are not
-    byte-wise equal will be sorted according to their byte values.
+    case</quote> or <quote>ignore accents</quote> or similar (using the
+    <literal>ks</literal> key), in order for such collations to act in a
+    truly case- or accent-insensitive manner, they also need to be declared as not
+    <firstterm>deterministic</firstterm> in <command>CREATE COLLATION</command>;
+    see <xref linkend="collation-nondeterministic"/>.
+    Otherwise, any strings that compare equal according to the collation but
+    are not byte-wise equal will be sorted according to their byte values.
    </para>
 
    <note>
@@ -883,6 +885,55 @@ <title>Copying Collations</title>
    </para>
    </sect4>
    </sect3>
+
+   <sect3 id="collation-nondeterministic">
+    <title>Nondeterminstic Collations</title>
+
+    <para>
+     A collation is either <firstterm>deterministic</firstterm> or
+     <firstterm>nondeterministic</firstterm>.  A deterministic collation uses
+     deterministic comparisons, which means that it considers strings to be
+     equal only if they consist of the same byte sequence.  Nondeterministic
+     comparison may determine strings to be equal even if they consist of
+     different bytes.  Typical situations include case-insensitive comparison,
+     accent-insensitive comparison, as well as comparion of strings in
+     different Unicode normal forms.  It is up to the collation provider to
+     actually implement such insensitive comparisons; the deterministic flag
+     only determines whether ties are to be broken using bytewise comparison.
+     See also <ulink url="https://unicode.org/reports/tr10">Unicode Technical
+     Standard 10</ulink> for more information on the terminology.
+    </para>
+
+    <para>
+     To create a nondeterministic collation, specify the property
+     <literal>deterministic = false</literal> to <command>CREATE
+     COLLATION</command>, for example:
+<programlisting>
+CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
+</programlisting>
+     This example would use the standard Unicode collation in a
+     nondeterministic way.  In particular, this would allow strings in
+     different normal forms to be compared correctly.  More interesting
+     examples make use of the ICU customization facilities explained above.
+     For example:
+<programlisting>
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+</programlisting>
+    </para>
+
+    <para>
+     All standard and predefined collations are deterministic, all
+     user-defined collations are deterministic by default.  While
+     nondeterministic collations give a more <quote>correct</quote> behavior,
+     especially when considering the full power of Unicode and its many
+     special cases, they also have some drawbacks.  Foremost, their use leads
+     to a performance penalty.  Also, certain operations are not possible with
+     nondeterministic collations, such as pattern matching operations.
+     Therefore, they should be used only in cases where they are specifically
+     wanted.
+    </para>
+   </sect3>
   </sect2>
  </sect1>
 
diff --git a/doc/src/sgml/citext.sgml b/doc/src/sgml/citext.sgml
index b1fe7101b2..85aa339d8b 100644
--- a/doc/src/sgml/citext.sgml
+++ b/doc/src/sgml/citext.sgml
@@ -14,6 +14,16 @@ <title>citext</title>
   exactly like <type>text</type>.
  </para>
 
+ <tip>
+  <para>
+   Consider using <firstterm>nondeterministic collations</firstterm> (see
+   <xref linkend="collation-nondeterministic"/>) instead of this module.  They
+   can be used for case-insensitive comparisons, accent-insensitive
+   comparisons, and other combinations, and they handle more Unicode special
+   cases correctly.
+  </para>
+ </tip>
+
  <sect2>
   <title>Rationale</title>
 
@@ -246,6 +256,17 @@ <title>Limitations</title>
       will be invoked instead.
     </para>
     </listitem>
+
+    <listitem>
+     <para>
+      The approach of lower-casing strings for comparison does not handle some
+      Unicode special cases correctly, for example when one upper-case letter
+      has two lower-case letter equivalents.  Unicode distinguishes between
+      <firstterm>case mapping</firstterm> and <firstterm>case
+      folding</firstterm> for this reason.  Use nondeterministic collations
+      instead of <type>citext</type> to handle that correctly.
+     </para>
+    </listitem>
    </itemizedlist>
  </sect2>
 
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 3a99e209a2..1a01473291 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -4065,6 +4065,12 @@ <title>Pattern Matching</title>
     </para>
    </caution>
 
+   <para>
+    The pattern matching operators of all three kinds do not support
+    nondeterministic collations.  If required, apply a different collation to
+    the expression to work around this limitation.
+   </para>
+
   <sect2 id="functions-like">
    <title><function>LIKE</function></title>
 
diff --git a/doc/src/sgml/ref/create_collation.sgml b/doc/src/sgml/ref/create_collation.sgml
index 038797fce1..def4dda6e8 100644
--- a/doc/src/sgml/ref/create_collation.sgml
+++ b/doc/src/sgml/ref/create_collation.sgml
@@ -23,6 +23,7 @@
     [ LC_COLLATE = <replaceable>lc_collate</replaceable>, ]
     [ LC_CTYPE = <replaceable>lc_ctype</replaceable>, ]
     [ PROVIDER = <replaceable>provider</replaceable>, ]
+    [ DETERMINISTIC = <replaceable>boolean</replaceable>, ]
     [ VERSION = <replaceable>version</replaceable> ]
 )
 CREATE COLLATION [ IF NOT EXISTS ] <replaceable>name</replaceable> FROM <replaceable>existing_collation</replaceable>
@@ -124,6 +125,27 @@ <title>Parameters</title>
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><literal>DETERMINISTIC</literal></term>
+
+     <listitem>
+      <para>
+       Specifies whether the collation should use deterministic comparisons.
+       The default is true.  A deterministic comparison considers strings that
+       are not byte-wise equal to be unequal even if they are considered
+       logically equal by the comparison.  PostgreSQL breaks ties using a
+       byte-wise comparison.  Comparison that is not deterministic can make the
+       collation be, say, case- or accent-insensitive.  For that, you need to
+       choose an appropriate <literal>LC_COLLATE</literal> setting
+       <emphasis>and</emphasis> set the collation to not deterministic here.
+      </para>
+
+      <para>
+       Nondeterministic collations are only supported with the ICU provider.
+      </para>
+     </listitem>
+    </varlistentry>
+
     <varlistentry>
      <term><replaceable>version</replaceable></term>
 
diff --git a/src/backend/access/hash/hashfunc.c b/src/backend/access/hash/hashfunc.c
index e5f3d42e04..0bf15ae723 100644
--- a/src/backend/access/hash/hashfunc.c
+++ b/src/backend/access/hash/hashfunc.c
@@ -27,8 +27,10 @@
 #include "postgres.h"
 
 #include "access/hash.h"
+#include "catalog/pg_collation.h"
 #include "utils/builtins.h"
 #include "utils/hashutils.h"
+#include "utils/pg_locale.h"
 
 /*
  * Datatype-specific hash functions.
@@ -243,15 +245,51 @@ Datum
 hashtext(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/*
-	 * Note: this is currently identical in behavior to hashvarlena, but keep
-	 * it as a separate function in case we someday want to do something
-	 * different in non-C locales.  (See also hashbpchar, if so.)
-	 */
-	result = hash_any((unsigned char *) VARDATA_ANY(key),
-					  VARSIZE_ANY_EXHDR(key));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) VARDATA_ANY(key),
+						  VARSIZE_ANY_EXHDR(key));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -263,12 +301,52 @@ Datum
 hashtextextended(PG_FUNCTION_ARGS)
 {
 	text	   *key = PG_GETARG_TEXT_PP(0);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
-	/* Same approach as hashtext */
-	result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
-							   VARSIZE_ANY_EXHDR(key),
-							   PG_GETARG_INT64(1));
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) VARDATA_ANY(key),
+								   VARSIZE_ANY_EXHDR(key),
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index 39cd391529..d22998c54b 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -630,7 +630,8 @@ spg_text_leaf_consistent(PG_FUNCTION_ARGS)
 			 * query (prefix) string, so we don't need to check it again.
 			 */
 			res = (level >= queryLen) ||
-				DatumGetBool(DirectFunctionCall2(text_starts_with,
+				DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
+													 PG_GET_COLLATION(),
 												 out->leafValue,
 												 PointerGetDatum(query)));
 
diff --git a/src/backend/catalog/pg_collation.c b/src/backend/catalog/pg_collation.c
index 74e1e82cb9..dd99d53547 100644
--- a/src/backend/catalog/pg_collation.c
+++ b/src/backend/catalog/pg_collation.c
@@ -46,6 +46,7 @@ Oid
 CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
@@ -160,6 +161,7 @@ CollationCreate(const char *collname, Oid collnamespace,
 	values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
 	values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
 	values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
+	values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
 	values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
 	namestrcpy(&name_collate, collcollate);
 	values[Anum_pg_collation_collcollate - 1] = NameGetDatum(&name_collate);
diff --git a/src/backend/commands/collationcmds.c b/src/backend/commands/collationcmds.c
index ed3f1c12e5..919e092483 100644
--- a/src/backend/commands/collationcmds.c
+++ b/src/backend/commands/collationcmds.c
@@ -59,10 +59,12 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	DefElem    *lccollateEl = NULL;
 	DefElem    *lcctypeEl = NULL;
 	DefElem    *providerEl = NULL;
+	DefElem    *deterministicEl = NULL;
 	DefElem    *versionEl = NULL;
 	char	   *collcollate = NULL;
 	char	   *collctype = NULL;
 	char	   *collproviderstr = NULL;
+	bool		collisdeterministic = true;
 	int			collencoding = 0;
 	char		collprovider = 0;
 	char	   *collversion = NULL;
@@ -91,6 +93,8 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 			defelp = &lcctypeEl;
 		else if (strcmp(defel->defname, "provider") == 0)
 			defelp = &providerEl;
+		else if (strcmp(defel->defname, "deterministic") == 0)
+			defelp = &deterministicEl;
 		else if (strcmp(defel->defname, "version") == 0)
 			defelp = &versionEl;
 		else
@@ -125,6 +129,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 		collcollate = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collcollate));
 		collctype = pstrdup(NameStr(((Form_pg_collation) GETSTRUCT(tp))->collctype));
 		collprovider = ((Form_pg_collation) GETSTRUCT(tp))->collprovider;
+		collisdeterministic = ((Form_pg_collation) GETSTRUCT(tp))->collisdeterministic;
 		collencoding = ((Form_pg_collation) GETSTRUCT(tp))->collencoding;
 
 		ReleaseSysCache(tp);
@@ -157,6 +162,9 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 	if (providerEl)
 		collproviderstr = defGetString(providerEl);
 
+	if (deterministicEl)
+		collisdeterministic = defGetBoolean(deterministicEl);
+
 	if (versionEl)
 		collversion = defGetString(versionEl);
 
@@ -185,6 +193,16 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 				 errmsg("parameter \"lc_ctype\" must be specified")));
 
+	/*
+	 * Nondeterministic collations are currently only supported with ICU
+	 * because that's the only case where it can actually make a difference.
+	 * So we can save writing the code for the other providers.
+	 */
+	if (!collisdeterministic && collprovider != COLLPROVIDER_ICU)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations not supported with this provider")));
+
 	if (!fromEl)
 	{
 		if (collprovider == COLLPROVIDER_ICU)
@@ -203,6 +221,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters, bool if_not_e
 							 collNamespace,
 							 GetUserId(),
 							 collprovider,
+							 collisdeterministic,
 							 collencoding,
 							 collcollate,
 							 collctype,
@@ -586,7 +605,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			 * about existing ones.
 			 */
 			collid = CollationCreate(localebuf, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 localebuf, localebuf,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, localebuf),
 									 true, true);
@@ -647,7 +666,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 			int			enc = aliases[i].enc;
 
 			collid = CollationCreate(alias, nspid, GetUserId(),
-									 COLLPROVIDER_LIBC, enc,
+									 COLLPROVIDER_LIBC, true, enc,
 									 locale, locale,
 									 get_collation_actual_version(COLLPROVIDER_LIBC, locale),
 									 true, true);
@@ -709,7 +728,7 @@ pg_import_system_collations(PG_FUNCTION_ARGS)
 
 			collid = CollationCreate(psprintf("%s-x-icu", langtag),
 									 nspid, GetUserId(),
-									 COLLPROVIDER_ICU, -1,
+									 COLLPROVIDER_ICU, true, -1,
 									 collcollate, collcollate,
 									 get_collation_actual_version(COLLPROVIDER_ICU, collcollate),
 									 true, true);
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..d4723fced8 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -901,7 +901,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		{
 			const char *qSchemaName = quote_identifier(schemaName);
 
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("@extschema@"),
 										CStringGetTextDatum(qSchemaName));
@@ -913,7 +914,8 @@ execute_extension_script(Oid extensionOid, ExtensionControlFile *control,
 		 */
 		if (control->module_pathname)
 		{
-			t_sql = DirectFunctionCall3(replace_text,
+			t_sql = DirectFunctionCall3Coll(replace_text,
+											C_COLLATION_OID,
 										t_sql,
 										CStringGetTextDatum("MODULE_PATHNAME"),
 										CStringGetTextDatum(control->module_pathname));
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 7cbf9d3bc1..0fb31f5c3d 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -3317,6 +3317,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	ExprState  *state = makeNode(ExprState);
@@ -3377,6 +3378,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		Form_pg_attribute latt = TupleDescAttr(ldesc, attno - 1);
 		Form_pg_attribute ratt = TupleDescAttr(rdesc, attno - 1);
 		Oid			foid = eqfunctions[natt];
+		Oid			collid = collations[natt];
 		FmgrInfo   *finfo;
 		FunctionCallInfo fcinfo;
 		AclResult	aclresult;
@@ -3394,7 +3396,7 @@ ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 		fmgr_info(foid, finfo);
 		fmgr_info_set_expr(NULL, finfo);
 		InitFunctionCallInfoData(*fcinfo, finfo, 2,
-								 InvalidOid, NULL, NULL);
+								 collid, NULL, NULL);
 
 		/* left arg */
 		scratch.opcode = EEOP_INNER_VAR;
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index 417e971ec8..14ee8db3f9 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -60,6 +60,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent)
 {
 	Oid		   *eqFunctions = (Oid *) palloc(numCols * sizeof(Oid));
@@ -75,7 +76,7 @@ execTuplesMatchPrepare(TupleDesc desc,
 
 	/* build actual expression */
 	expr = ExecBuildGroupingEqual(desc, desc, NULL, NULL,
-								  numCols, keyColIdx, eqFunctions,
+								  numCols, keyColIdx, eqFunctions, collations,
 								  parent);
 
 	return expr;
@@ -155,6 +156,7 @@ BuildTupleHashTableExt(PlanState *parent,
 					   int numCols, AttrNumber *keyColIdx,
 					   const Oid *eqfuncoids,
 					   FmgrInfo *hashfunctions,
+					   Oid *collations,
 					   long nbuckets, Size additionalsize,
 					   MemoryContext metacxt,
 					   MemoryContext tablecxt,
@@ -177,6 +179,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->numCols = numCols;
 	hashtable->keyColIdx = keyColIdx;
 	hashtable->tab_hash_funcs = hashfunctions;
+	hashtable->tab_collations = collations;
 	hashtable->tablecxt = tablecxt;
 	hashtable->tempcxt = tempcxt;
 	hashtable->entrysize = entrysize;
@@ -212,7 +215,7 @@ BuildTupleHashTableExt(PlanState *parent,
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
 													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
 													numCols,
-													keyColIdx, eqfuncoids,
+													keyColIdx, eqfuncoids, collations,
 													NULL);
 
 	/*
@@ -240,6 +243,7 @@ BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt,
@@ -250,6 +254,7 @@ BuildTupleHashTable(PlanState *parent,
 								  numCols, keyColIdx,
 								  eqfuncoids,
 								  hashfunctions,
+								  collations,
 								  nbuckets, additionalsize,
 								  tablecxt,
 								  tablecxt,
@@ -421,8 +426,9 @@ TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
 		{
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
-												attr));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i],
+													hashtable->tab_collations[i],
+													attr));
 			hashkey ^= hkey;
 		}
 	}
diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 37e96a6013..cfad8a38f0 100644
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -1246,6 +1246,7 @@ get_partition_for_tuple(PartitionDispatch pd, Datum *values, bool *isnull)
 				greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
 				rowHash = compute_partition_hash_value(key->partnatts,
 													   key->partsupfunc,
+													   key->partcollation,
 													   values, isnull);
 
 				part_index = boundinfo->indexes[rowHash % greatest_modulus];
diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 95dfc4987d..c539bb5a3f 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -96,6 +96,8 @@ build_replindex_scan_key(ScanKey skey, Relation rel, Relation idxrel,
 					regop,
 					searchslot->tts_values[mainattno - 1]);
 
+		skey[attoff].sk_collation = idxrel->rd_indcollation[attoff];
+
 		/* Check for null value. */
 		if (searchslot->tts_isnull[mainattno - 1])
 		{
@@ -262,7 +264,8 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2)
 					 errmsg("could not identify an equality operator for type %s",
 							format_type_be(att->atttypid))));
 
-		if (!DatumGetBool(FunctionCall2(&typentry->eq_opr_finfo,
+		if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
+											att->attcollation,
 										slot1->tts_values[attrnum],
 										slot2->tts_values[attrnum])))
 			return false;
diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index bae7989a42..47161afbd4 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -746,15 +746,14 @@ process_ordered_aggregate_single(AggState *aggstate,
 
 		/*
 		 * If DISTINCT mode, and not distinct from prior, skip it.
-		 *
-		 * Note: we assume equality functions don't care about collation.
 		 */
 		if (isDistinct &&
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
 			  oldAbbrevVal == newAbbrevVal &&
-			  DatumGetBool(FunctionCall2(&pertrans->equalfnOne,
+			  DatumGetBool(FunctionCall2Coll(&pertrans->equalfnOne,
+											 pertrans->aggCollation,
 										 oldVal, *newVal)))))
 		{
 			/* equal to prior, so forget this one */
@@ -1287,6 +1286,7 @@ build_hash_table(AggState *aggstate)
 														perhash->hashGrpColIdxHash,
 														perhash->eqfuncoids,
 														perhash->hashfunctions,
+														perhash->aggnode->grpCollations,
 														perhash->aggnode->numGroups,
 														additionalsize,
 														aggstate->ss.ps.state->es_query_cxt,
@@ -2381,6 +2381,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   length,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 
@@ -2392,6 +2393,7 @@ ExecInitAgg(Agg *node, EState *estate, int eflags)
 											   aggnode->numCols,
 											   aggnode->grpColIdx,
 											   aggnode->grpOperators,
+											   aggnode->grpCollations,
 											   (PlanState *) aggstate);
 				}
 			}
@@ -3155,6 +3157,7 @@ build_pertrans_for_aggref(AggStatePerTrans pertrans,
 									   numDistinctCols,
 									   pertrans->sortColIdx,
 									   ops,
+									   pertrans->sortCollations,
 									   &aggstate->ss.ps);
 		pfree(ops);
 	}
diff --git a/src/backend/executor/nodeGroup.c b/src/backend/executor/nodeGroup.c
index 655084d7b5..05f1d33150 100644
--- a/src/backend/executor/nodeGroup.c
+++ b/src/backend/executor/nodeGroup.c
@@ -212,6 +212,7 @@ ExecInitGroup(Group *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->grpColIdx,
 							   node->grpOperators,
+							   node->grpCollations,
 							   &grpstate->ss.ps);
 
 	return grpstate;
diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 856daf6a7f..64eec91f8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -425,7 +425,7 @@ ExecEndHash(HashState *node)
  * ----------------------------------------------------------------
  */
 HashJoinTable
-ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
+ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations, bool keepNulls)
 {
 	Hash	   *node;
 	HashJoinTable hashtable;
@@ -439,6 +439,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	int			nkeys;
 	int			i;
 	ListCell   *ho;
+	ListCell   *hc;
 	MemoryContext oldcxt;
 
 	/*
@@ -541,8 +542,9 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 	hashtable->inner_hashfunctions =
 		(FmgrInfo *) palloc(nkeys * sizeof(FmgrInfo));
 	hashtable->hashStrict = (bool *) palloc(nkeys * sizeof(bool));
+	hashtable->collations = (Oid *) palloc(nkeys * sizeof(Oid));
 	i = 0;
-	foreach(ho, hashOperators)
+	forboth(ho, hashOperators, hc, hashCollations)
 	{
 		Oid			hashop = lfirst_oid(ho);
 		Oid			left_hashfn;
@@ -554,6 +556,7 @@ ExecHashTableCreate(HashState *state, List *hashOperators, bool keepNulls)
 		fmgr_info(left_hashfn, &hashtable->outer_hashfunctions[i]);
 		fmgr_info(right_hashfn, &hashtable->inner_hashfunctions[i]);
 		hashtable->hashStrict[i] = op_strict(hashop);
+		hashtable->collations[i] = lfirst_oid(hc);
 		i++;
 	}
 
@@ -1847,7 +1850,7 @@ ExecHashGetHashValue(HashJoinTable hashtable,
 			/* Compute the hash function */
 			uint32		hkey;
 
-			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i], keyval));
+			hkey = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[i], hashtable->collations[i], keyval));
 			hashkey ^= hkey;
 		}
 
@@ -2303,8 +2306,9 @@ ExecHashBuildSkewHash(HashJoinTable hashtable, Hash *node, int mcvsToUse)
 			uint32		hashvalue;
 			int			bucket;
 
-			hashvalue = DatumGetUInt32(FunctionCall1(&hashfunctions[0],
-													 sslot.values[i]));
+			hashvalue = DatumGetUInt32(FunctionCall1Coll(&hashfunctions[0],
+														 hashtable->collations[0],
+														 sslot.values[i]));
 
 			/*
 			 * While we have not hit a hole in the hashtable and have not hit
diff --git a/src/backend/executor/nodeHashjoin.c b/src/backend/executor/nodeHashjoin.c
index 2098708864..aa43296e26 100644
--- a/src/backend/executor/nodeHashjoin.c
+++ b/src/backend/executor/nodeHashjoin.c
@@ -278,6 +278,7 @@ ExecHashJoinImpl(PlanState *pstate, bool parallel)
 				 */
 				hashtable = ExecHashTableCreate(hashNode,
 												node->hj_HashOperators,
+												node->hj_Collations,
 												HJ_FILL_INNER(node));
 				node->hj_HashTable = hashtable;
 
@@ -603,6 +604,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	List	   *rclauses;
 	List	   *rhclauses;
 	List	   *hoperators;
+	List	   *hcollations;
 	TupleDesc	outerDesc,
 				innerDesc;
 	ListCell   *l;
@@ -738,6 +740,7 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 	rclauses = NIL;
 	rhclauses = NIL;
 	hoperators = NIL;
+	hcollations = NIL;
 	foreach(l, node->hashclauses)
 	{
 		OpExpr	   *hclause = lfirst_node(OpExpr, l);
@@ -749,10 +752,12 @@ ExecInitHashJoin(HashJoin *node, EState *estate, int eflags)
 		rhclauses = lappend(rhclauses, ExecInitExpr(lsecond(hclause->args),
 												   innerPlanState(hjstate)));
 		hoperators = lappend_oid(hoperators, hclause->opno);
+		hcollations = lappend_oid(hcollations, hclause->inputcollid);
 	}
 	hjstate->hj_OuterHashKeys = lclauses;
 	hjstate->hj_InnerHashKeys = rclauses;
 	hjstate->hj_HashOperators = hoperators;
+	hjstate->hj_Collations = hcollations;
 	/* child Hash node needs to evaluate inner hash keys, too */
 	((HashState *) innerPlanState(hjstate))->hashkeys = rhclauses;
 
diff --git a/src/backend/executor/nodeRecursiveunion.c b/src/backend/executor/nodeRecursiveunion.c
index 9b74ed3208..9c5eed7def 100644
--- a/src/backend/executor/nodeRecursiveunion.c
+++ b/src/backend/executor/nodeRecursiveunion.c
@@ -43,6 +43,7 @@ build_hash_table(RecursiveUnionState *rustate)
 												node->dupColIdx,
 												rustate->eqfuncoids,
 												rustate->hashfunctions,
+												node->dupCollations,
 												node->numGroups,
 												0,
 												rustate->ps.state->es_query_cxt,
diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index 26aeaee083..044246aa09 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -132,6 +132,7 @@ build_hash_table(SetOpState *setopstate)
 												   node->dupColIdx,
 												   setopstate->eqfuncoids,
 												   setopstate->hashfunctions,
+												   node->dupCollations,
 												   node->numGroups,
 												   0,
 												   setopstate->ps.state->es_query_cxt,
@@ -554,6 +555,7 @@ ExecInitSetOp(SetOp *node, EState *estate, int eflags)
 								   node->numCols,
 								   node->dupColIdx,
 								   node->dupOperators,
+								   node->dupCollations,
 								   &setopstate->ps);
 
 	if (node->strategy == SETOP_HASHED)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index d7d076758c..749b4eced3 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -514,6 +514,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 												 node->keyColIdx,
 												 node->tab_eq_funcoids,
 												 node->tab_hash_funcs,
+												 node->tab_collations,
 												 nbuckets,
 												 0,
 												 node->planstate->state->es_query_cxt,
@@ -541,6 +542,7 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
 													 node->keyColIdx,
 													 node->tab_eq_funcoids,
 													 node->tab_hash_funcs,
+													 node->tab_collations,
 													 nbuckets,
 													 0,
 													 node->planstate->state->es_query_cxt,
@@ -642,6 +644,7 @@ execTuplesUnequal(TupleTableSlot *slot1,
 				  int numCols,
 				  AttrNumber *matchColIdx,
 				  FmgrInfo *eqfunctions,
+				  const Oid *collations,
 				  MemoryContext evalContext)
 {
 	MemoryContext oldContext;
@@ -679,8 +682,8 @@ execTuplesUnequal(TupleTableSlot *slot1,
 			continue;			/* can't prove anything here */
 
 		/* Apply the type-specific equality function */
-
-		if (!DatumGetBool(FunctionCall2(&eqfunctions[i],
+		if (!DatumGetBool(FunctionCall2Coll(&eqfunctions[i],
+											collations[i],
 										attr1, attr2)))
 		{
 			result = true;		/* they are unequal */
@@ -722,6 +725,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
 		if (!execTuplesUnequal(slot, hashtable->tableslot,
 							   numCols, keyColIdx,
 							   eqfunctions,
+							   hashtable->tab_collations,
 							   hashtable->tempcxt))
 		{
 			TermTupleHashIterator(&hashiter);
@@ -817,6 +821,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 	sstate->tab_eq_funcoids = NULL;
 	sstate->tab_hash_funcs = NULL;
 	sstate->tab_eq_funcs = NULL;
+	sstate->tab_collations = NULL;
 	sstate->lhs_hash_funcs = NULL;
 	sstate->cur_eq_funcs = NULL;
 
@@ -915,6 +920,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 		sstate->tab_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->tab_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+		sstate->tab_collations = (Oid *) palloc(ncols * sizeof(Oid));
 		sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
 		i = 1;
@@ -965,6 +971,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 			fmgr_info(left_hashfn, &sstate->lhs_hash_funcs[i - 1]);
 			fmgr_info(right_hashfn, &sstate->tab_hash_funcs[i - 1]);
 
+			/* Set collation */
+			sstate->tab_collations[i - 1] = opexpr->inputcollid;
+
 			i++;
 		}
 
@@ -1001,6 +1010,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
 													 ncols,
 													 sstate->keyColIdx,
 													 sstate->tab_eq_funcoids,
+													 sstate->tab_collations,
 													 parent);
 
 	}
diff --git a/src/backend/executor/nodeUnique.c b/src/backend/executor/nodeUnique.c
index ad7039937d..c553f150b8 100644
--- a/src/backend/executor/nodeUnique.c
+++ b/src/backend/executor/nodeUnique.c
@@ -152,6 +152,7 @@ ExecInitUnique(Unique *node, EState *estate, int eflags)
 							   node->numCols,
 							   node->uniqColIdx,
 							   node->uniqOperators,
+							   node->uniqCollations,
 							   &uniquestate->ps);
 
 	return uniquestate;
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 157ac042b8..b090828c01 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2370,6 +2370,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->partNumCols,
 								   node->partColIdx,
 								   node->partOperators,
+								   node->partCollations,
 								   &winstate->ss.ps);
 
 	if (node->ordNumCols > 0)
@@ -2378,6 +2379,7 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
 								   node->ordNumCols,
 								   node->ordColIdx,
 								   node->ordOperators,
+								   node->ordCollations,
 								   &winstate->ss.ps);
 
 	/*
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index a8a735c247..d6fe35374b 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -297,6 +297,7 @@ _copyRecursiveUnion(const RecursiveUnion *from)
 	{
 		COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 
@@ -956,6 +957,7 @@ _copyGroup(const Group *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -977,6 +979,7 @@ _copyAgg(const Agg *from)
 	{
 		COPY_POINTER_FIELD(grpColIdx, from->numCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(grpOperators, from->numCols * sizeof(Oid));
+		COPY_POINTER_FIELD(grpCollations, from->numCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(numGroups);
 	COPY_BITMAPSET_FIELD(aggParams);
@@ -1002,12 +1005,14 @@ _copyWindowAgg(const WindowAgg *from)
 	{
 		COPY_POINTER_FIELD(partColIdx, from->partNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(partOperators, from->partNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(partCollations, from->partNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(ordNumCols);
 	if (from->ordNumCols > 0)
 	{
 		COPY_POINTER_FIELD(ordColIdx, from->ordNumCols * sizeof(AttrNumber));
 		COPY_POINTER_FIELD(ordOperators, from->ordNumCols * sizeof(Oid));
+		COPY_POINTER_FIELD(ordCollations, from->ordNumCols * sizeof(Oid));
 	}
 	COPY_SCALAR_FIELD(frameOptions);
 	COPY_NODE_FIELD(startOffset);
@@ -1040,6 +1045,7 @@ _copyUnique(const Unique *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->numCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -1089,6 +1095,7 @@ _copySetOp(const SetOp *from)
 	COPY_SCALAR_FIELD(numCols);
 	COPY_POINTER_FIELD(dupColIdx, from->numCols * sizeof(AttrNumber));
 	COPY_POINTER_FIELD(dupOperators, from->numCols * sizeof(Oid));
+	COPY_POINTER_FIELD(dupCollations, from->numCols * sizeof(Oid));
 	COPY_SCALAR_FIELD(flagColIdx);
 	COPY_SCALAR_FIELD(firstFlag);
 	COPY_SCALAR_FIELD(numGroups);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 69179a07c3..910a738c20 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -463,6 +463,7 @@ _outRecursiveUnion(StringInfo str, const RecursiveUnion *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 }
 
@@ -774,6 +775,7 @@ _outAgg(StringInfo str, const Agg *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 	WRITE_LONG_FIELD(numGroups);
 	WRITE_BITMAPSET_FIELD(aggParams);
 	WRITE_NODE_FIELD(groupingSets);
@@ -791,9 +793,11 @@ _outWindowAgg(StringInfo str, const WindowAgg *node)
 	WRITE_INT_FIELD(partNumCols);
 	WRITE_ATTRNUMBER_ARRAY(partColIdx, node->partNumCols);
 	WRITE_OID_ARRAY(partOperators, node->partNumCols);
+	WRITE_OID_ARRAY(partCollations, node->partNumCols);
 	WRITE_INT_FIELD(ordNumCols);
 	WRITE_ATTRNUMBER_ARRAY(ordColIdx, node->ordNumCols);
 	WRITE_OID_ARRAY(ordOperators, node->ordNumCols);
+	WRITE_OID_ARRAY(ordCollations, node->ordNumCols);
 	WRITE_INT_FIELD(frameOptions);
 	WRITE_NODE_FIELD(startOffset);
 	WRITE_NODE_FIELD(endOffset);
@@ -814,6 +818,7 @@ _outGroup(StringInfo str, const Group *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(grpColIdx, node->numCols);
 	WRITE_OID_ARRAY(grpOperators, node->numCols);
+	WRITE_OID_ARRAY(grpCollations, node->numCols);
 }
 
 static void
@@ -848,6 +853,7 @@ _outUnique(StringInfo str, const Unique *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->numCols);
 	WRITE_OID_ARRAY(uniqOperators, node->numCols);
+	WRITE_OID_ARRAY(uniqCollations, node->numCols);
 }
 
 static void
@@ -875,6 +881,7 @@ _outSetOp(StringInfo str, const SetOp *node)
 	WRITE_INT_FIELD(numCols);
 	WRITE_ATTRNUMBER_ARRAY(dupColIdx, node->numCols);
 	WRITE_OID_ARRAY(dupOperators, node->numCols);
+	WRITE_OID_ARRAY(dupCollations, node->numCols);
 	WRITE_INT_FIELD(flagColIdx);
 	WRITE_INT_FIELD(firstFlag);
 	WRITE_LONG_FIELD(numGroups);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 4b845b1bb7..eff98febf1 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1677,6 +1677,7 @@ _readRecursiveUnion(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 
 	READ_DONE();
@@ -2143,6 +2144,7 @@ _readGroup(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2162,6 +2164,7 @@ _readAgg(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(grpColIdx, local_node->numCols);
 	READ_OID_ARRAY(grpOperators, local_node->numCols);
+	READ_OID_ARRAY(grpCollations, local_node->numCols);
 	READ_LONG_FIELD(numGroups);
 	READ_BITMAPSET_FIELD(aggParams);
 	READ_NODE_FIELD(groupingSets);
@@ -2184,9 +2187,11 @@ _readWindowAgg(void)
 	READ_INT_FIELD(partNumCols);
 	READ_ATTRNUMBER_ARRAY(partColIdx, local_node->partNumCols);
 	READ_OID_ARRAY(partOperators, local_node->partNumCols);
+	READ_OID_ARRAY(partCollations, local_node->partNumCols);
 	READ_INT_FIELD(ordNumCols);
 	READ_ATTRNUMBER_ARRAY(ordColIdx, local_node->ordNumCols);
 	READ_OID_ARRAY(ordOperators, local_node->ordNumCols);
+	READ_OID_ARRAY(ordCollations, local_node->ordNumCols);
 	READ_INT_FIELD(frameOptions);
 	READ_NODE_FIELD(startOffset);
 	READ_NODE_FIELD(endOffset);
@@ -2212,6 +2217,7 @@ _readUnique(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
 	READ_OID_ARRAY(uniqOperators, local_node->numCols);
+	READ_OID_ARRAY(uniqCollations, local_node->numCols);
 
 	READ_DONE();
 }
@@ -2290,6 +2296,7 @@ _readSetOp(void)
 	READ_INT_FIELD(numCols);
 	READ_ATTRNUMBER_ARRAY(dupColIdx, local_node->numCols);
 	READ_OID_ARRAY(dupOperators, local_node->numCols);
+	READ_OID_ARRAY(dupCollations, local_node->numCols);
 	READ_INT_FIELD(flagColIdx);
 	READ_INT_FIELD(firstFlag);
 	READ_LONG_FIELD(numGroups);
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 9fbe5b2a5f..93c56c657c 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -260,14 +260,14 @@ static Sort *make_sort_from_groupcols(List *groupcls,
 						 Plan *lefttree);
 static Material *make_material(Plan *lefttree);
 static WindowAgg *make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
 			   Plan *lefttree);
 static Group *make_group(List *tlist, List *qual, int numGroupCols,
-		   AttrNumber *grpColIdx, Oid *grpOperators,
+		   AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		   Plan *lefttree);
 static Unique *make_unique_from_sortclauses(Plan *lefttree, List *distinctList);
 static Unique *make_unique_from_pathkeys(Plan *lefttree,
@@ -1387,6 +1387,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	bool		newitems;
 	int			numGroupCols;
 	AttrNumber *groupColIdx;
+	Oid		   *groupCollations;
 	int			groupColPos;
 	ListCell   *l;
 
@@ -1453,6 +1454,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	newtlist = subplan->targetlist;
 	numGroupCols = list_length(uniq_exprs);
 	groupColIdx = (AttrNumber *) palloc(numGroupCols * sizeof(AttrNumber));
+	groupCollations = (Oid *) palloc(numGroupCols * sizeof(Oid));
 
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
@@ -1463,7 +1465,9 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 		tle = tlist_member(uniqexpr, newtlist);
 		if (!tle)				/* shouldn't happen */
 			elog(ERROR, "failed to find unique expression in subplan tlist");
-		groupColIdx[groupColPos++] = tle->resno;
+		groupColIdx[groupColPos] = tle->resno;
+		groupCollations[groupColPos] = exprCollation((Node *) tle->expr);
+		groupColPos++;
 	}
 
 	if (best_path->umethod == UNIQUE_PATH_HASH)
@@ -1501,6 +1505,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 								 numGroupCols,
 								 groupColIdx,
 								 groupOperators,
+								 groupCollations,
 								 NIL,
 								 NIL,
 								 best_path->path.rows,
@@ -1883,6 +1888,8 @@ create_group_plan(PlannerInfo *root, GroupPath *best_path)
 					  extract_grouping_cols(best_path->groupClause,
 											subplan->targetlist),
 					  extract_grouping_ops(best_path->groupClause),
+					  extract_grouping_collations(best_path->groupClause,
+												  subplan->targetlist),
 					  subplan);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -1949,6 +1956,8 @@ create_agg_plan(PlannerInfo *root, AggPath *best_path)
 					extract_grouping_cols(best_path->groupClause,
 										  subplan->targetlist),
 					extract_grouping_ops(best_path->groupClause),
+					extract_grouping_collations(best_path->groupClause,
+												subplan->targetlist),
 					NIL,
 					NIL,
 					best_path->numGroups,
@@ -2110,6 +2119,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 										 list_length((List *) linitial(rollup->gsets)),
 										 new_grpColIdx,
 										 extract_grouping_ops(rollup->groupClause),
+										 extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 										 rollup->gsets,
 										 NIL,
 										 rollup->numGroups,
@@ -2147,6 +2157,7 @@ create_groupingsets_plan(PlannerInfo *root, GroupingSetsPath *best_path)
 						numGroupCols,
 						top_grpColIdx,
 						extract_grouping_ops(rollup->groupClause),
+						extract_grouping_collations(rollup->groupClause, subplan->targetlist),
 						rollup->gsets,
 						chain,
 						rollup->numGroups,
@@ -2246,9 +2257,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	int			partNumCols;
 	AttrNumber *partColIdx;
 	Oid		   *partOperators;
+	Oid		   *partCollations;
 	int			ordNumCols;
 	AttrNumber *ordColIdx;
 	Oid		   *ordOperators;
+	Oid		   *ordCollations;
 	ListCell   *lc;
 
 	/*
@@ -2270,6 +2283,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 	 */
 	partColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numPart);
 	partOperators = (Oid *) palloc(sizeof(Oid) * numPart);
+	partCollations = (Oid *) palloc(sizeof(Oid) * numPart);
 
 	partNumCols = 0;
 	foreach(lc, wc->partitionClause)
@@ -2280,11 +2294,13 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		partColIdx[partNumCols] = tle->resno;
 		partOperators[partNumCols] = sgc->eqop;
+		partCollations[partNumCols] = exprCollation((Node *) tle->expr);
 		partNumCols++;
 	}
 
 	ordColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numOrder);
 	ordOperators = (Oid *) palloc(sizeof(Oid) * numOrder);
+	ordCollations = (Oid *) palloc(sizeof(Oid) * numOrder);
 
 	ordNumCols = 0;
 	foreach(lc, wc->orderClause)
@@ -2295,6 +2311,7 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 		Assert(OidIsValid(sgc->eqop));
 		ordColIdx[ordNumCols] = tle->resno;
 		ordOperators[ordNumCols] = sgc->eqop;
+		ordCollations[ordNumCols] = exprCollation((Node *) tle->expr);
 		ordNumCols++;
 	}
 
@@ -2304,9 +2321,11 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path)
 						  partNumCols,
 						  partColIdx,
 						  partOperators,
+						  partCollations,
 						  ordNumCols,
 						  ordColIdx,
 						  ordOperators,
+						  ordCollations,
 						  wc->frameOptions,
 						  wc->startOffset,
 						  wc->endOffset,
@@ -5326,10 +5345,12 @@ make_recursive_union(List *tlist,
 		int			keyno = 0;
 		AttrNumber *dupColIdx;
 		Oid		   *dupOperators;
+		Oid		   *dupCollations;
 		ListCell   *slitem;
 
 		dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 		dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+		dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 		foreach(slitem, distinctList)
 		{
@@ -5339,11 +5360,13 @@ make_recursive_union(List *tlist,
 
 			dupColIdx[keyno] = tle->resno;
 			dupOperators[keyno] = sortcl->eqop;
+			dupCollations[keyno] = exprCollation((Node *) tle->expr);
 			Assert(OidIsValid(dupOperators[keyno]));
 			keyno++;
 		}
 		node->dupColIdx = dupColIdx;
 		node->dupOperators = dupOperators;
+		node->dupCollations = dupCollations;
 	}
 	node->numGroups = numGroups;
 
@@ -6015,7 +6038,7 @@ materialize_finished_plan(Plan *subplan)
 Agg *
 make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree)
 {
@@ -6031,6 +6054,7 @@ make_agg(List *tlist, List *qual,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 	node->numGroups = numGroups;
 	node->aggParams = NULL;		/* SS_finalize_plan() will fill this */
 	node->groupingSets = groupingSets;
@@ -6046,8 +6070,8 @@ make_agg(List *tlist, List *qual,
 
 static WindowAgg *
 make_windowagg(List *tlist, Index winref,
-			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators,
-			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators,
+			   int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
+			   int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
 			   int frameOptions, Node *startOffset, Node *endOffset,
 			   Oid startInRangeFunc, Oid endInRangeFunc,
 			   Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst,
@@ -6060,9 +6084,11 @@ make_windowagg(List *tlist, Index winref,
 	node->partNumCols = partNumCols;
 	node->partColIdx = partColIdx;
 	node->partOperators = partOperators;
+	node->partCollations = partCollations;
 	node->ordNumCols = ordNumCols;
 	node->ordColIdx = ordColIdx;
 	node->ordOperators = ordOperators;
+	node->ordCollations = ordCollations;
 	node->frameOptions = frameOptions;
 	node->startOffset = startOffset;
 	node->endOffset = endOffset;
@@ -6087,6 +6113,7 @@ make_group(List *tlist,
 		   int numGroupCols,
 		   AttrNumber *grpColIdx,
 		   Oid *grpOperators,
+		   Oid *grpCollations,
 		   Plan *lefttree)
 {
 	Group	   *node = makeNode(Group);
@@ -6095,6 +6122,7 @@ make_group(List *tlist,
 	node->numCols = numGroupCols;
 	node->grpColIdx = grpColIdx;
 	node->grpOperators = grpOperators;
+	node->grpCollations = grpCollations;
 
 	plan->qual = qual;
 	plan->targetlist = tlist;
@@ -6118,6 +6146,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6132,6 +6161,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	Assert(numCols > 0);
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6140,6 +6170,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = sortcl->eqop;
+		uniqCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(uniqOperators[keyno]));
 		keyno++;
 	}
@@ -6147,6 +6178,7 @@ make_unique_from_sortclauses(Plan *lefttree, List *distinctList)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6162,6 +6194,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	int			keyno = 0;
 	AttrNumber *uniqColIdx;
 	Oid		   *uniqOperators;
+	Oid		   *uniqCollations;
 	ListCell   *lc;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6177,6 +6210,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	Assert(numCols >= 0 && numCols <= list_length(pathkeys));
 	uniqColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	uniqOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	uniqCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(lc, pathkeys)
 	{
@@ -6245,6 +6279,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 
 		uniqColIdx[keyno] = tle->resno;
 		uniqOperators[keyno] = eqop;
+		uniqCollations[keyno] = ec->ec_collation;
 
 		keyno++;
 	}
@@ -6252,6 +6287,7 @@ make_unique_from_pathkeys(Plan *lefttree, List *pathkeys, int numCols)
 	node->numCols = numCols;
 	node->uniqColIdx = uniqColIdx;
 	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
@@ -6296,6 +6332,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	int			keyno = 0;
 	AttrNumber *dupColIdx;
 	Oid		   *dupOperators;
+	Oid		   *dupCollations;
 	ListCell   *slitem;
 
 	plan->targetlist = lefttree->targetlist;
@@ -6309,6 +6346,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	 */
 	dupColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
 	dupOperators = (Oid *) palloc(sizeof(Oid) * numCols);
+	dupCollations = (Oid *) palloc(sizeof(Oid) * numCols);
 
 	foreach(slitem, distinctList)
 	{
@@ -6317,6 +6355,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 
 		dupColIdx[keyno] = tle->resno;
 		dupOperators[keyno] = sortcl->eqop;
+		dupCollations[keyno] = exprCollation((Node *) tle->expr);
 		Assert(OidIsValid(dupOperators[keyno]));
 		keyno++;
 	}
@@ -6326,6 +6365,7 @@ make_setop(SetOpCmd cmd, SetOpStrategy strategy, Plan *lefttree,
 	node->numCols = numCols;
 	node->dupColIdx = dupColIdx;
 	node->dupOperators = dupOperators;
+	node->dupCollations = dupCollations;
 	node->flagColIdx = flagColIdx;
 	node->firstFlag = firstFlag;
 	node->numGroups = numGroups;
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 14d1c67a94..bb3b7969f2 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -503,6 +503,31 @@ extract_grouping_ops(List *groupClause)
 	return groupOperators;
 }
 
+/*
+ * extract_grouping_collations - make an array of the grouping column collations
+ *		for a SortGroupClause list
+ */
+Oid *
+extract_grouping_collations(List *groupClause, List *tlist)
+{
+	int			numCols = list_length(groupClause);
+	int			colno = 0;
+	Oid		   *grpCollations;
+	ListCell   *glitem;
+
+	grpCollations = (Oid *) palloc(sizeof(Oid) * numCols);
+
+	foreach(glitem, groupClause)
+	{
+		SortGroupClause *groupcl = (SortGroupClause *) lfirst(glitem);
+		TargetEntry *tle = get_sortgroupclause_tle(groupcl, tlist);
+
+		grpCollations[colno++] = exprCollation((Node *) tle->expr);
+	}
+
+	return grpCollations;
+}
+
 /*
  * extract_grouping_cols - make an array of the grouping column resnos
  *		for a SortGroupClause list
diff --git a/src/backend/partitioning/partbounds.c b/src/backend/partitioning/partbounds.c
index 5b897d50ee..803c23aaf5 100644
--- a/src/backend/partitioning/partbounds.c
+++ b/src/backend/partitioning/partbounds.c
@@ -2657,7 +2657,7 @@ get_range_nulltest(PartitionKey key)
  * Compute the hash value for given partition key values.
  */
 uint64
-compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc, Oid *partcollation,
 							 Datum *values, bool *isnull)
 {
 	int			i;
@@ -2678,7 +2678,7 @@ compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
 			 * datatype-specific hash functions of each partition key
 			 * attribute.
 			 */
-			hash = FunctionCall2(&partsupfunc[i], values[i], seed);
+			hash = FunctionCall2Coll(&partsupfunc[i], partcollation[i], values[i], seed);
 
 			/* Form a single 64-bit hash value */
 			rowHash = hash_combine64(rowHash, DatumGetUInt64(hash));
diff --git a/src/backend/partitioning/partprune.c b/src/backend/partitioning/partprune.c
index b5c0889935..31e0164ea9 100644
--- a/src/backend/partitioning/partprune.c
+++ b/src/backend/partitioning/partprune.c
@@ -2159,6 +2159,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 	int			i;
 	uint64		rowHash;
 	int			greatest_modulus;
+	Oid		   *partcollation = context->partcollation;
 
 	Assert(context->strategy == PARTITION_STRATEGY_HASH);
 
@@ -2179,7 +2180,7 @@ get_matching_hash_bounds(PartitionPruneContext *context,
 			isnull[i] = bms_is_member(i, nullkeys);
 
 		greatest_modulus = get_hash_partition_greatest_modulus(boundinfo);
-		rowHash = compute_partition_hash_value(partnatts, partsupfunc,
+		rowHash = compute_partition_hash_value(partnatts, partsupfunc, partcollation,
 											   values, isnull);
 
 		if (partindices[rowHash % greatest_modulus] >= 0)
diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index a8c0b156fa..4a808b7606 100644
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -263,6 +263,11 @@ pg_set_regex_collation(Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 
+		if (pg_regex_locale && !pg_regex_locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for regular expressions")));
+
 #ifdef USE_ICU
 		if (pg_regex_locale && pg_regex_locale->provider == COLLPROVIDER_ICU)
 			pg_regex_strategy = PG_REGEX_LOCALE_ICU;
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index a34605ac94..9cef018c0b 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -3957,7 +3957,7 @@ hash_array(PG_FUNCTION_ARGS)
 	 * apply the hash function to each array element.
 	 */
 	InitFunctionCallInfoData(*locfcinfo, &typentry->hash_proc_finfo, 1,
-							 InvalidOid, NULL, NULL);
+							 PG_GET_COLLATION(), NULL, NULL);
 
 	/* Loop over source data */
 	nitems = ArrayGetNItems(ndims, dims);
diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 853c9c01e9..704e5720cf 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -45,7 +45,7 @@ static int UTF8_MatchText(const char *t, int tlen, const char *p, int plen,
 static int SB_IMatchText(const char *t, int tlen, const char *p, int plen,
 			  pg_locale_t locale, bool locale_is_c);
 
-static int	GenericMatchText(const char *s, int slen, const char *p, int plen);
+static int	GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation);
 static int	Generic_Text_IC_like(text *str, text *pat, Oid collation);
 
 /*--------------------
@@ -148,8 +148,18 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 
 /* Generic for all cases not requiring inline case-folding */
 static inline int
-GenericMatchText(const char *s, int slen, const char *p, int plen)
+GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
 {
+	if (collation && !lc_ctype_is_c(collation) && collation != DEFAULT_COLLATION_OID)
+	{
+		pg_locale_t		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for LIKE")));
+	}
+
 	if (pg_database_encoding_max_length() == 1)
 		return SB_MatchText(s, slen, p, plen, 0, true);
 	else if (GetDatabaseEncoding() == PG_UTF8)
@@ -184,6 +194,11 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 					 errhint("Use the COLLATE clause to set the collation explicitly.")));
 		}
 		locale = pg_newlocale_from_collation(collation);
+
+		if (locale && !locale->deterministic)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("nondeterministic collations are not supported for ILIKE")));
 	}
 
 	/*
@@ -240,7 +255,7 @@ namelike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -261,7 +276,7 @@ namenlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -282,7 +297,7 @@ textlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) == LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) == LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
@@ -303,7 +318,7 @@ textnlike(PG_FUNCTION_ARGS)
 	p = VARDATA_ANY(pat);
 	plen = VARSIZE_ANY_EXHDR(pat);
 
-	result = (GenericMatchText(s, slen, p, plen) != LIKE_TRUE);
+	result = (GenericMatchText(s, slen, p, plen, PG_GET_COLLATION()) != LIKE_TRUE);
 
 	PG_RETURN_BOOL(result);
 }
diff --git a/src/backend/utils/adt/like_support.c b/src/backend/utils/adt/like_support.c
index 69509811ef..a65e63736c 100644
--- a/src/backend/utils/adt/like_support.c
+++ b/src/backend/utils/adt/like_support.c
@@ -257,6 +257,20 @@ match_pattern_prefix(Node *leftop,
 		return NIL;
 	patt = (Const *) rightop;
 
+	/*
+	 * Not supported if the expression collation is nondeterministic.  The
+	 * optimized equality or prefix tests use bytewise comparisons, which is
+	 * not consistent with nondeterministic collations.  The actual
+	 * pattern-matching implementation functions will later error out that
+	 * pattern-matching is not supported with nondeterministic collations.
+	 * (We could also error out here, but by doing it later we get more
+	 * precise error messages.)  (It should be possible to support at least
+	 * Pattern_Prefix_Exact, but no point as along as the actual
+	 * pattern-matching implementations don't support it.)
+	 */
+	if (!get_collation_isdeterministic(expr_coll))
+		return NIL;
+
 	/*
 	 * Try to extract a fixed prefix from the pattern.
 	 */
diff --git a/src/backend/utils/adt/name.c b/src/backend/utils/adt/name.c
index 3a7887d455..54425925ed 100644
--- a/src/backend/utils/adt/name.c
+++ b/src/backend/utils/adt/name.c
@@ -131,14 +131,26 @@ namesend(PG_FUNCTION_ARGS)
  * have a '\0' terminator.  Whatever might be past the terminator is not
  * considered relevant to comparisons.
  */
+static int
+namecmp(Name arg1, Name arg2, Oid collid)
+{
+	/* Fast path for common case used in system catalogs */
+	if (collid == C_COLLATION_OID)
+		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
+
+	/* Else rely on the varstr infrastructure */
+	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
+					  NameStr(*arg2), strlen(NameStr(*arg2)),
+					  collid);
+}
+
 Datum
 nameeq(PG_FUNCTION_ARGS)
 {
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) == 0);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) == 0);
 }
 
 Datum
@@ -147,21 +159,7 @@ namene(PG_FUNCTION_ARGS)
 	Name		arg1 = PG_GETARG_NAME(0);
 	Name		arg2 = PG_GETARG_NAME(1);
 
-	/* Collation doesn't matter: equal only if bitwise-equal */
-	PG_RETURN_BOOL(strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN) != 0);
-}
-
-static int
-namecmp(Name arg1, Name arg2, Oid collid)
-{
-	/* Fast path for common case used in system catalogs */
-	if (collid == C_COLLATION_OID)
-		return strncmp(NameStr(*arg1), NameStr(*arg2), NAMEDATALEN);
-
-	/* Else rely on the varstr infrastructure */
-	return varstr_cmp(NameStr(*arg1), strlen(NameStr(*arg1)),
-					  NameStr(*arg2), strlen(NameStr(*arg2)),
-					  collid);
+	PG_RETURN_BOOL(namecmp(arg1, arg2, PG_GET_COLLATION()) != 0);
 }
 
 Datum
diff --git a/src/backend/utils/adt/orderedsetaggs.c b/src/backend/utils/adt/orderedsetaggs.c
index 2d384a9944..4db2d0d0e1 100644
--- a/src/backend/utils/adt/orderedsetaggs.c
+++ b/src/backend/utils/adt/orderedsetaggs.c
@@ -1084,7 +1084,7 @@ mode_final(PG_FUNCTION_ARGS)
 			last_abbrev_val = abbrev_val;
 		}
 		else if (abbrev_val == last_abbrev_val &&
-				 DatumGetBool(FunctionCall2(equalfn, val, last_val)))
+				 DatumGetBool(FunctionCall2Coll(equalfn, PG_GET_COLLATION(), val, last_val)))
 		{
 			/* value equal to previous value, count it */
 			if (last_val_is_mode)
@@ -1345,6 +1345,7 @@ hypothetical_dense_rank_final(PG_FUNCTION_ARGS)
 											  numDistinctCols,
 											  sortColIdx,
 											  osastate->qstate->eqOperators,
+											  osastate->qstate->sortCollations,
 											  NULL);
 		MemoryContextSwitchTo(oldContext);
 		osastate->qstate->compareTuple = compareTuple;
diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index ec14bad4e3..f35be5d822 100644
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -1312,6 +1312,7 @@ pg_newlocale_from_collation(Oid collid)
 		/* We'll fill in the result struct locally before allocating memory */
 		memset(&result, 0, sizeof(result));
 		result.provider = collform->collprovider;
+		result.deterministic = collform->collisdeterministic;
 
 		if (collform->collprovider == COLLPROVIDER_LIBC)
 		{
diff --git a/src/backend/utils/adt/ri_triggers.c b/src/backend/utils/adt/ri_triggers.c
index d715709b7c..f32747ceda 100644
--- a/src/backend/utils/adt/ri_triggers.c
+++ b/src/backend/utils/adt/ri_triggers.c
@@ -675,6 +675,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -683,6 +685,8 @@ ri_restrict(TriggerData *trigdata, bool is_no_action)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = "AND";
 			queryoids[i] = pk_type;
 		}
@@ -777,6 +781,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -785,6 +791,8 @@ RI_FKey_cascade_del(PG_FUNCTION_ARGS)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = "AND";
 			queryoids[i] = pk_type;
 		}
@@ -889,6 +897,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -900,6 +910,8 @@ RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = ",";
 			qualsep = "AND";
 			queryoids[i] = pk_type;
@@ -1064,6 +1076,8 @@ ri_set(TriggerData *trigdata, bool is_set_null)
 		{
 			Oid			pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
 			Oid			fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
+			Oid			pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
+			Oid			fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);
 
 			quoteOneName(attname,
 						 RIAttName(fk_rel, riinfo->fk_attnums[i]));
@@ -1076,6 +1090,8 @@ ri_set(TriggerData *trigdata, bool is_set_null)
 							paramname, pk_type,
 							riinfo->pf_eq_oprs[i],
 							attname, fk_type);
+			if (pk_coll != fk_coll && !get_collation_isdeterministic(pk_coll))
+				ri_GenerateQualCollation(&querybuf, pk_coll);
 			querysep = ",";
 			qualsep = "AND";
 			queryoids[i] = pk_type;
@@ -2475,11 +2491,20 @@ ri_AttributesEqual(Oid eq_opr, Oid typeid,
 	}
 
 	/*
-	 * Apply the comparison operator.  We assume it doesn't care about
-	 * collations.
+	 * Apply the comparison operator.
+	 *
+	 * Note: This function is part of a call stack that determines whether an
+	 * update to a row is significant enough that it needs checking or action
+	 * on the other side of a foreign-key constraint.  Therefore, the
+	 * comparison here would need to be done with the collation of the *other*
+	 * table.  For simplicity (e.g., we might not even have the other table
+	 * open), we'll just use the default collation here, which could lead to
+	 * some false negatives.  All this would break if we ever allow
+	 * database-wide collations to be nondeterministic.
 	 */
-	return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
-									  oldvalue, newvalue));
+	return DatumGetBool(FunctionCall2Coll(&entry->eq_opr_finfo,
+										  DEFAULT_COLLATION_OID,
+										  oldvalue, newvalue));
 }
 
 /*
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 440fc8ed66..4003631d8f 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -23,6 +23,8 @@
 #include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/hashutils.h"
+#include "utils/lsyscache.h"
+#include "utils/pg_locale.h"
 #include "utils/varlena.h"
 #include "mb/pg_wchar.h"
 
@@ -717,6 +719,22 @@ bpcharoctetlen(PG_FUNCTION_ARGS)
  * need to be so careful.
  *****************************************************************************/
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 Datum
 bpchareq(PG_FUNCTION_ARGS)
 {
@@ -725,18 +743,31 @@ bpchareq(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
+
+	check_collation_set(collid);
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = false;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = false;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) == 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) == 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -752,18 +783,29 @@ bpcharne(PG_FUNCTION_ARGS)
 	int			len1,
 				len2;
 	bool		result;
+	Oid			collid = PG_GET_COLLATION();
 
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.
-	 */
-	if (len1 != len2)
-		result = true;
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.
+		 */
+		if (len1 != len2)
+			result = true;
+		else
+			result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	}
 	else
-		result = (memcmp(VARDATA_ANY(arg1), VARDATA_ANY(arg2), len1) != 0);
+	{
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1, VARDATA_ANY(arg2), len2,
+							 collid) != 0);
+	}
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -933,23 +975,60 @@ bpchar_smaller(PG_FUNCTION_ARGS)
 /*
  * bpchar needs a specialized hash function because we want to ignore
  * trailing blanks in comparisons.
- *
- * Note: currently there is no need for locale-specific behavior here,
- * but if we ever change the semantics of bpchar comparison to trust
- * strcoll() completely, we'd need to do something different in non-C locales.
  */
 Datum
 hashbpchar(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any((unsigned char *) keydata, keylen);
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any((unsigned char *) keydata, keylen);
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, keydata, keylen);
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any(buf, bsize);
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	/* Avoid leaking memory for toasted inputs */
 	PG_FREE_IF_COPY(key, 0);
@@ -961,15 +1040,56 @@ Datum
 hashbpcharextended(PG_FUNCTION_ARGS)
 {
 	BpChar	   *key = PG_GETARG_BPCHAR_PP(0);
+	Oid			collid = PG_GET_COLLATION();
 	char	   *keydata;
 	int			keylen;
+	pg_locale_t	mylocale = 0;
 	Datum		result;
 
+	if (!collid)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string hashing"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+
 	keydata = VARDATA_ANY(key);
 	keylen = bcTruelen(key);
 
-	result = hash_any_extended((unsigned char *) keydata, keylen,
-							   PG_GETARG_INT64(1));
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (!mylocale || mylocale->deterministic)
+	{
+		result = hash_any_extended((unsigned char *) keydata, keylen,
+								   PG_GETARG_INT64(1));
+	}
+	else
+	{
+#ifdef USE_ICU
+		if (mylocale->provider == COLLPROVIDER_ICU)
+		{
+			int32_t		ulen = -1;
+			UChar	   *uchar = NULL;
+			Size		bsize;
+			uint8_t	   *buf;
+
+			ulen = icu_to_uchar(&uchar, VARDATA_ANY(key), VARSIZE_ANY_EXHDR(key));
+
+			bsize = ucol_getSortKey(mylocale->info.icu.ucol,
+									uchar, ulen, NULL, 0);
+			buf = palloc(bsize);
+			ucol_getSortKey(mylocale->info.icu.ucol,
+							uchar, ulen, buf, bsize);
+
+			result = hash_any_extended(buf, bsize, PG_GETARG_INT64(1));
+
+			pfree(buf);
+		}
+		else
+#endif
+			/* shouldn't happen */
+			elog(ERROR, "unsupported collprovider: %c", mylocale->provider);
+	}
 
 	PG_FREE_IF_COPY(key, 0);
 
@@ -985,12 +1105,23 @@ hashbpcharextended(PG_FUNCTION_ARGS)
  */
 
 static int
-internal_bpchar_pattern_compare(BpChar *arg1, BpChar *arg2)
+internal_bpchar_pattern_compare(BpChar *arg1, BpChar *arg2, Oid collid)
 {
 	int			result;
 	int			len1,
 				len2;
 
+	check_collation_set(collid);
+
+	/*
+	 * see internal_text_pattern_compare()
+	 */
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"bpchar_pattern_ops")));
+
 	len1 = bcTruelen(arg1);
 	len2 = bcTruelen(arg2);
 
@@ -1013,7 +1144,7 @@ bpchar_pattern_lt(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1029,7 +1160,7 @@ bpchar_pattern_le(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1045,7 +1176,7 @@ bpchar_pattern_ge(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1061,7 +1192,7 @@ bpchar_pattern_gt(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1077,7 +1208,7 @@ btbpchar_pattern_cmp(PG_FUNCTION_ARGS)
 	BpChar	   *arg2 = PG_GETARG_BPCHAR_PP(1);
 	int			result;
 
-	result = internal_bpchar_pattern_compare(arg1, arg2);
+	result = internal_bpchar_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -1090,8 +1221,17 @@ Datum
 btbpchar_pattern_sortsupport(PG_FUNCTION_ARGS)
 {
 	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
+	Oid			collid = ssup->ssup_collation;
 	MemoryContext oldcontext;
 
+	check_collation_set(collid);
+
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"bpchar_pattern_ops")));
+
 	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
 
 	/* Use generic string SortSupport, forcing "C" collation */
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 39c394331b..68a6e49aeb 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -122,13 +122,14 @@ static text *text_substring(Datum str,
 			   int32 length,
 			   bool length_not_specified);
 static text *text_overlay(text *t1, text *t2, int sp, int sl);
-static int	text_position(text *t1, text *t2);
-static void text_position_setup(text *t1, text *t2, TextPositionState *state);
+static int	text_position(text *t1, text *t2, Oid collid);
+static void text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state);
 static bool text_position_next(TextPositionState *state);
 static char *text_position_next_internal(char *start_ptr, TextPositionState *state);
 static char *text_position_get_match_ptr(TextPositionState *state);
 static int	text_position_get_match_pos(TextPositionState *state);
 static void text_position_cleanup(TextPositionState *state);
+static void check_collation_set(Oid collid);
 static int	text_cmp(text *arg1, text *arg2, Oid collid);
 static bytea *bytea_catenate(bytea *t1, bytea *t2);
 static bytea *bytea_substring(Datum str,
@@ -1094,7 +1095,7 @@ textpos(PG_FUNCTION_ARGS)
 	text	   *str = PG_GETARG_TEXT_PP(0);
 	text	   *search_str = PG_GETARG_TEXT_PP(1);
 
-	PG_RETURN_INT32((int32) text_position(str, search_str));
+	PG_RETURN_INT32((int32) text_position(str, search_str, PG_GET_COLLATION()));
 }
 
 /*
@@ -1112,7 +1113,7 @@ textpos(PG_FUNCTION_ARGS)
  *	functions.
  */
 static int
-text_position(text *t1, text *t2)
+text_position(text *t1, text *t2, Oid collid)
 {
 	TextPositionState state;
 	int			result;
@@ -1120,7 +1121,7 @@ text_position(text *t1, text *t2)
 	if (VARSIZE_ANY_EXHDR(t1) < 1 || VARSIZE_ANY_EXHDR(t2) < 1)
 		return 0;
 
-	text_position_setup(t1, t2, &state);
+	text_position_setup(t1, t2, collid, &state);
 	if (!text_position_next(&state))
 		result = 0;
 	else
@@ -1147,10 +1148,21 @@ text_position(text *t1, text *t2)
  */
 
 static void
-text_position_setup(text *t1, text *t2, TextPositionState *state)
+text_position_setup(text *t1, text *t2, Oid collid, TextPositionState *state)
 {
 	int			len1 = VARSIZE_ANY_EXHDR(t1);
 	int			len2 = VARSIZE_ANY_EXHDR(t2);
+	pg_locale_t	mylocale = 0;
+
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
 
 	Assert(len1 > 0);
 	Assert(len2 > 0);
@@ -1429,6 +1441,22 @@ text_position_cleanup(TextPositionState *state)
 	/* no cleanup needed */
 }
 
+static void
+check_collation_set(Oid collid)
+{
+	if (!OidIsValid(collid))
+	{
+		/*
+		 * This typically means that the parser could not resolve a conflict
+		 * of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for string comparison"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+}
+
 /* varstr_cmp()
  * Comparison function for text strings with given lengths.
  * Includes locale support, but must copy strings to temporary memory
@@ -1441,6 +1469,8 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 {
 	int			result;
 
+	check_collation_set(collid);
+
 	/*
 	 * Unfortunately, there is no strncoll(), so in the non-C locale case we
 	 * have to do some memory copying.  This turns out to be significantly
@@ -1462,20 +1492,7 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		pg_locale_t mylocale = 0;
 
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			mylocale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * memcmp() can't tell us which of two unequal strings sorts first,
@@ -1558,13 +1575,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 				ereport(ERROR,
 						(errmsg("could not compare Unicode strings: %m")));
 
-			/*
-			 * In some locales wcscoll() can claim that nonidentical strings
-			 * are equal.  Believing that would be bad news for a number of
-			 * reasons, so we follow Perl's lead and sort "equal" strings
-			 * according to strcmp (on the UTF-8 representation).
-			 */
-			if (result == 0)
+			/* Break tie if necessary. */
+			if (result == 0 &&
+				(!mylocale || mylocale->deterministic))
 			{
 				result = memcmp(arg1, arg2, Min(len1, len2));
 				if ((result == 0) && (len1 != len2))
@@ -1649,13 +1662,9 @@ varstr_cmp(const char *arg1, int len1, const char *arg2, int len2, Oid collid)
 		else
 			result = strcoll(a1p, a2p);
 
-		/*
-		 * In some locales strcoll() can claim that nonidentical strings are
-		 * equal.  Believing that would be bad news for a number of reasons,
-		 * so we follow Perl's lead and sort "equal" strings according to
-		 * strcmp().
-		 */
-		if (result == 0)
+		/* Break tie if necessary. */
+		if (result == 0 &&
+			(!mylocale || mylocale->deterministic))
 			result = strcmp(a1p, a2p);
 
 		if (a1p != a1buf)
@@ -1699,33 +1708,52 @@ text_cmp(text *arg1, text *arg2, Oid collid)
 Datum
 texteq(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/*
-	 * Since we only care about equality or not-equality, we can avoid all the
-	 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
-	 * don't even have to do a bitwise comparison if we can show the lengths
-	 * of the strings are unequal; which might save us from having to detoast
-	 * one or both values.
-	 */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = false;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/*
+		 * Since we only care about equality or not-equality, we can avoid all the
+		 * expense of strcoll() here, and just do bitwise comparison.  In fact, we
+		 * don't even have to do a bitwise comparison if we can show the lengths
+		 * of the strings are unequal; which might save us from having to detoast
+		 * one or both values.
+		 */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = false;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) == 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) == 0);
+		result = (text_cmp(arg1, arg2, collid) == 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1734,27 +1762,46 @@ texteq(PG_FUNCTION_ARGS)
 Datum
 textne(PG_FUNCTION_ARGS)
 {
-	Datum		arg1 = PG_GETARG_DATUM(0);
-	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
-	Size		len1,
-				len2;
 
-	/* See comment in texteq() */
-	len1 = toast_raw_datum_size(arg1);
-	len2 = toast_raw_datum_size(arg2);
-	if (len1 != len2)
-		result = true;
+	check_collation_set(collid);
+
+	if (lc_collate_is_c(collid) ||
+		collid == DEFAULT_COLLATION_OID ||
+		pg_newlocale_from_collation(collid)->deterministic)
+	{
+		Datum		arg1 = PG_GETARG_DATUM(0);
+		Datum		arg2 = PG_GETARG_DATUM(1);
+		Size		len1,
+					len2;
+
+		/* See comment in texteq() */
+		len1 = toast_raw_datum_size(arg1);
+		len2 = toast_raw_datum_size(arg2);
+		if (len1 != len2)
+			result = true;
+		else
+		{
+			text	   *targ1 = DatumGetTextPP(arg1);
+			text	   *targ2 = DatumGetTextPP(arg2);
+
+			result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
+							 len1 - VARHDRSZ) != 0);
+
+			PG_FREE_IF_COPY(targ1, 0);
+			PG_FREE_IF_COPY(targ2, 1);
+		}
+	}
 	else
 	{
-		text	   *targ1 = DatumGetTextPP(arg1);
-		text	   *targ2 = DatumGetTextPP(arg2);
+		text	   *arg1 = PG_GETARG_TEXT_PP(0);
+		text	   *arg2 = PG_GETARG_TEXT_PP(1);
 
-		result = (memcmp(VARDATA_ANY(targ1), VARDATA_ANY(targ2),
-						 len1 - VARHDRSZ) != 0);
+		result = (text_cmp(arg1, arg2, collid) != 0);
 
-		PG_FREE_IF_COPY(targ1, 0);
-		PG_FREE_IF_COPY(targ2, 1);
+		PG_FREE_IF_COPY(arg1, 0);
+		PG_FREE_IF_COPY(arg2, 1);
 	}
 
 	PG_RETURN_BOOL(result);
@@ -1825,10 +1872,22 @@ text_starts_with(PG_FUNCTION_ARGS)
 {
 	Datum		arg1 = PG_GETARG_DATUM(0);
 	Datum		arg2 = PG_GETARG_DATUM(1);
+	Oid			collid = PG_GET_COLLATION();
+	pg_locale_t	mylocale = 0;
 	bool		result;
 	Size		len1,
 				len2;
 
+	check_collation_set(collid);
+
+	if (!lc_collate_is_c(collid) && collid != DEFAULT_COLLATION_OID)
+		mylocale = pg_newlocale_from_collation(collid);
+
+	if (mylocale && !mylocale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for substring searches")));
+
 	len1 = toast_raw_datum_size(arg1);
 	len2 = toast_raw_datum_size(arg2);
 	if (len2 > len1)
@@ -1898,6 +1957,8 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 	VarStringSortSupport *sss;
 	pg_locale_t locale = 0;
 
+	check_collation_set(collid);
+
 	/*
 	 * If possible, set ssup->comparator to a function which can be used to
 	 * directly compare two datums.  If we can do this, we'll avoid the
@@ -1934,20 +1995,7 @@ varstr_sortsupport(SortSupport ssup, Oid typid, Oid collid)
 		 * result.
 		 */
 		if (collid != DEFAULT_COLLATION_OID)
-		{
-			if (!OidIsValid(collid))
-			{
-				/*
-				 * This typically means that the parser could not resolve a
-				 * conflict of implicit collations, so report it that way.
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_INDETERMINATE_COLLATION),
-						 errmsg("could not determine which collation to use for string comparison"),
-						 errhint("Use the COLLATE clause to set the collation explicitly.")));
-			}
 			locale = pg_newlocale_from_collation(collid);
-		}
 
 		/*
 		 * There is a further exception on Windows.  When the database
@@ -2328,12 +2376,9 @@ varstrfastcmp_locale(char *a1p, int len1, char *a2p, int len2, SortSupport ssup)
 	else
 		result = strcoll(sss->buf1, sss->buf2);
 
-	/*
-	 * In some locales strcoll() can claim that nonidentical strings are
-	 * equal. Believing that would be bad news for a number of reasons, so we
-	 * follow Perl's lead and sort "equal" strings according to strcmp().
-	 */
-	if (result == 0)
+	/* Break tie if necessary. */
+	if (result == 0 &&
+		(!sss->locale || sss->locale->deterministic))
 		result = strcmp(sss->buf1, sss->buf2);
 
 	/* Cache result, perhaps saving an expensive strcoll() call next time */
@@ -2760,10 +2805,18 @@ nameeqtext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = (varstr_cmp(NameStr(*arg1), len1,
+							 VARDATA_ANY(arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2777,10 +2830,18 @@ texteqname(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = (len1 == len2 &&
-			  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = (len1 == len2 &&
+				  memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = (varstr_cmp(VARDATA_ANY(arg1), len1,
+							 NameStr(*arg2), len2,
+							 collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2794,10 +2855,18 @@ namenetext(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	size_t		len1 = strlen(NameStr(*arg1));
 	size_t		len2 = VARSIZE_ANY_EXHDR(arg2);
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(NameStr(*arg1), VARDATA_ANY(arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(NameStr(*arg1), len1,
+							  VARDATA_ANY(arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg2, 1);
 
@@ -2811,10 +2880,18 @@ textnename(PG_FUNCTION_ARGS)
 	Name		arg2 = PG_GETARG_NAME(1);
 	size_t		len1 = VARSIZE_ANY_EXHDR(arg1);
 	size_t		len2 = strlen(NameStr(*arg2));
+	Oid			collid = PG_GET_COLLATION();
 	bool		result;
 
-	result = !(len1 == len2 &&
-			   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	check_collation_set(collid);
+
+	if (collid == C_COLLATION_OID)
+		result = !(len1 == len2 &&
+				   memcmp(VARDATA_ANY(arg1), NameStr(*arg2), len1) == 0);
+	else
+		result = !(varstr_cmp(VARDATA_ANY(arg1), len1,
+							  NameStr(*arg2), len2,
+							  collid) == 0);
 
 	PG_FREE_IF_COPY(arg1, 0);
 
@@ -2919,12 +2996,34 @@ textgename(PG_FUNCTION_ARGS)
  */
 
 static int
-internal_text_pattern_compare(text *arg1, text *arg2)
+internal_text_pattern_compare(text *arg1, text *arg2, Oid collid)
 {
 	int			result;
 	int			len1,
 				len2;
 
+	check_collation_set(collid);
+
+	/*
+	 * XXX We cannot use a text_pattern_ops index for nondeterministic
+	 * collations, because these operators intentionally ignore the collation.
+	 * However, the planner has no way to know that, so it might choose such
+	 * an index for an "=" clause, which would lead to wrong results.  This
+	 * check here doesn't prevent choosing the index, but it will at least
+	 * error out if the index is chosen.  A text_pattern_ops index on a column
+	 * with nondeterministic collation is pretty useless anyway, since LIKE
+	 * etc. won't work there either.  A future possibility would be to
+	 * annotate the operator class or its members in the catalog to avoid the
+	 * index.  Another alternative is to stay away from the *_pattern_ops
+	 * operator classes and prefer creating LIKE-supporting indexes with
+	 * COLLATE "C".
+	 */
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"text_pattern_ops")));
+
 	len1 = VARSIZE_ANY_EXHDR(arg1);
 	len2 = VARSIZE_ANY_EXHDR(arg2);
 
@@ -2947,7 +3046,7 @@ text_pattern_lt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2963,7 +3062,7 @@ text_pattern_le(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2979,7 +3078,7 @@ text_pattern_ge(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -2995,7 +3094,7 @@ text_pattern_gt(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3011,7 +3110,7 @@ bttext_pattern_cmp(PG_FUNCTION_ARGS)
 	text	   *arg2 = PG_GETARG_TEXT_PP(1);
 	int			result;
 
-	result = internal_text_pattern_compare(arg1, arg2);
+	result = internal_text_pattern_compare(arg1, arg2, PG_GET_COLLATION());
 
 	PG_FREE_IF_COPY(arg1, 0);
 	PG_FREE_IF_COPY(arg2, 1);
@@ -3024,8 +3123,17 @@ Datum
 bttext_pattern_sortsupport(PG_FUNCTION_ARGS)
 {
 	SortSupport ssup = (SortSupport) PG_GETARG_POINTER(0);
+	Oid			collid = ssup->ssup_collation;
 	MemoryContext oldcontext;
 
+	check_collation_set(collid);
+
+	if (!get_collation_isdeterministic(collid))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for operator class \"%s\"",
+						"text_pattern_ops")));
+
 	oldcontext = MemoryContextSwitchTo(ssup->ssup_cxt);
 
 	/* Use generic string SortSupport, forcing "C" collation */
@@ -4121,7 +4229,7 @@ replace_text(PG_FUNCTION_ARGS)
 		PG_RETURN_TEXT_P(src_text);
 	}
 
-	text_position_setup(src_text, from_sub_text, &state);
+	text_position_setup(src_text, from_sub_text, PG_GET_COLLATION(), &state);
 
 	found = text_position_next(&state);
 
@@ -4482,7 +4590,7 @@ split_text(PG_FUNCTION_ARGS)
 			PG_RETURN_TEXT_P(cstring_to_text(""));
 	}
 
-	text_position_setup(inputstring, fldsep, &state);
+	text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 	/* identify bounds of first field */
 	start_ptr = VARDATA_ANY(inputstring);
@@ -4538,11 +4646,12 @@ split_text(PG_FUNCTION_ARGS)
  * Convenience function to return true when two text params are equal.
  */
 static bool
-text_isequal(text *txt1, text *txt2)
+text_isequal(text *txt1, text *txt2, Oid collid)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq,
-											PointerGetDatum(txt1),
-											PointerGetDatum(txt2)));
+	return DatumGetBool(DirectFunctionCall2Coll(texteq,
+												collid,
+												PointerGetDatum(txt1),
+												PointerGetDatum(txt2)));
 }
 
 /*
@@ -4633,7 +4742,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 			int			lbs[1];
 
 			/* single element can be a NULL too */
-			is_null = null_string ? text_isequal(inputstring, null_string) : false;
+			is_null = null_string ? text_isequal(inputstring, null_string, PG_GET_COLLATION()) : false;
 
 			elems[0] = PointerGetDatum(inputstring);
 			nulls[0] = is_null;
@@ -4645,7 +4754,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 													 TEXTOID, -1, false, 'i'));
 		}
 
-		text_position_setup(inputstring, fldsep, &state);
+		text_position_setup(inputstring, fldsep, PG_GET_COLLATION(), &state);
 
 		start_ptr = VARDATA_ANY(inputstring);
 
@@ -4673,7 +4782,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
@@ -4715,7 +4824,7 @@ text_to_array_internal(PG_FUNCTION_ARGS)
 
 			/* must build a temp text datum to pass to accumArrayResult */
 			result_text = cstring_to_text_with_len(start_ptr, chunk_len);
-			is_null = null_string ? text_isequal(result_text, null_string) : false;
+			is_null = null_string ? text_isequal(result_text, null_string, PG_GET_COLLATION()) : false;
 
 			/* stash away this field */
 			astate = accumArrayResult(astate,
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 07e1cd7696..d05930bc4c 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -170,13 +170,18 @@ int4hashfast(Datum datum)
 static bool
 texteqfast(Datum a, Datum b)
 {
-	return DatumGetBool(DirectFunctionCall2(texteq, a, b));
+	/*
+	 * The use of DEFAULT_COLLATION_OID is fairly arbitrary here.  We just
+	 * want to take the fast "deterministic" path in texteq().
+	 */
+	return DatumGetBool(DirectFunctionCall2Coll(texteq, DEFAULT_COLLATION_OID, a, b));
 }
 
 static uint32
 texthashfast(Datum datum)
 {
-	return DatumGetInt32(DirectFunctionCall1(hashtext, datum));
+	/* analogously here as in texteqfast() */
+	return DatumGetInt32(DirectFunctionCall1Coll(hashtext, DEFAULT_COLLATION_OID, datum));
 }
 
 static bool
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e88c45d268..59e6bcd856 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -908,6 +908,22 @@ get_collation_name(Oid colloid)
 		return NULL;
 }
 
+bool
+get_collation_isdeterministic(Oid colloid)
+{
+	HeapTuple	tp;
+	Form_pg_collation colltup;
+	bool		result;
+
+	tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(colloid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for collation %u", colloid);
+	colltup = (Form_pg_collation) GETSTRUCT(tp);
+	result = colltup->collisdeterministic;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*				---------- CONSTRAINT CACHE ----------					 */
 
 /*
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index fd50a809ea..4886090132 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1765,8 +1765,8 @@ setup_collation(FILE *cmdfd)
 	 * in pg_collation.h.  But add it before reading system collations, so
 	 * that it wins if libc defines a locale named ucs_basic.
 	 */
-	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collencoding, collcollate, collctype)"
-				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', %d, 'C', 'C');\n\n",
+	PG_CMD_PRINTF3("INSERT INTO pg_collation (oid, collname, collnamespace, collowner, collprovider, collisdeterministic, collencoding, collcollate, collctype)"
+				   "VALUES (pg_nextoid('pg_catalog.pg_collation', 'oid', 'pg_catalog.pg_collation_oid_index'), 'ucs_basic', 'pg_catalog'::regnamespace, %u, '%c', true, %d, 'C', 'C');\n\n",
 				   BOOTSTRAP_SUPERUSERID, COLLPROVIDER_LIBC, PG_UTF8);
 
 	/* Now import all collations we can find in the operating system */
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4c98ae4d7f..63699932c1 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -13417,6 +13417,7 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	char	   *qcollname;
 	PGresult   *res;
 	int			i_collprovider;
+	int			i_collisdeterministic;
 	int			i_collcollate;
 	int			i_collctype;
 	const char *collprovider;
@@ -13434,28 +13435,35 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 	qcollname = pg_strdup(fmtId(collinfo->dobj.name));
 
 	/* Get collation-specific details */
+	appendPQExpBuffer(query, "SELECT ");
+
 	if (fout->remoteVersion >= 100000)
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "collversion, ");
 	else
-		appendPQExpBuffer(query, "SELECT "
+		appendPQExpBuffer(query,
 						  "'c' AS collprovider, "
-						  "collcollate, "
-						  "collctype, "
-						  "NULL AS collversion "
-						  "FROM pg_catalog.pg_collation c "
-						  "WHERE c.oid = '%u'::pg_catalog.oid",
-						  collinfo->dobj.catId.oid);
+						  "NULL AS collversion, ");
+
+	if (fout->remoteVersion >= 120000)
+		appendPQExpBuffer(query,
+						  "collisdeterministic, ");
+	else
+		appendPQExpBuffer(query,
+						  "true AS collisdeterministic, ");
+
+	appendPQExpBuffer(query,
+					  "collcollate, "
+					  "collctype "
+					  "FROM pg_catalog.pg_collation c "
+					  "WHERE c.oid = '%u'::pg_catalog.oid",
+					  collinfo->dobj.catId.oid);
 
 	res = ExecuteSqlQueryForSingleRow(fout, query->data);
 
 	i_collprovider = PQfnumber(res, "collprovider");
+	i_collisdeterministic = PQfnumber(res, "collisdeterministic");
 	i_collcollate = PQfnumber(res, "collcollate");
 	i_collctype = PQfnumber(res, "collctype");
 
@@ -13482,6 +13490,9 @@ dumpCollation(Archive *fout, CollInfo *collinfo)
 					  "unrecognized collation provider: %s\n",
 					  collprovider);
 
+	if (strcmp(PQgetvalue(res, 0, i_collisdeterministic), "f") == 0)
+		appendPQExpBufferStr(q, ", deterministic = false");
+
 	if (strcmp(collcollate, collctype) == 0)
 	{
 		appendPQExpBufferStr(q, ", locale = ");
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 779e48437c..fd8ebee8cd 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -4106,7 +4106,7 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 	PQExpBufferData buf;
 	PGresult   *res;
 	printQueryOpt myopt = pset.popt;
-	static const bool translate_columns[] = {false, false, false, false, false, false};
+	static const bool translate_columns[] = {false, false, false, false, false, true, false};
 
 	if (pset.sversion < 90100)
 	{
@@ -4134,6 +4134,21 @@ listCollations(const char *pattern, bool verbose, bool showSystem)
 		appendPQExpBuffer(&buf,
 						  ",\n       CASE c.collprovider WHEN 'd' THEN 'default' WHEN 'c' THEN 'libc' WHEN 'i' THEN 'icu' END AS \"%s\"",
 						  gettext_noop("Provider"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       'libc' AS \"%s\"",
+						  gettext_noop("Provider"));
+
+	if (pset.sversion >= 120000)
+		appendPQExpBuffer(&buf,
+						  ",\n       CASE WHEN c.collisdeterministic THEN '%s' ELSE '%s' END AS \"%s\"",
+						  gettext_noop("yes"), gettext_noop("no"),
+						  gettext_noop("Deterministic?"));
+	else
+		appendPQExpBuffer(&buf,
+						  ",\n       '%s' AS \"%s\"",
+						  gettext_noop("yes"),
+						  gettext_noop("Deterministic?"));
 
 	if (verbose)
 		appendPQExpBuffer(&buf,
diff --git a/src/include/catalog/pg_collation.h b/src/include/catalog/pg_collation.h
index 10fe711a91..4d2fcb3858 100644
--- a/src/include/catalog/pg_collation.h
+++ b/src/include/catalog/pg_collation.h
@@ -33,6 +33,7 @@ CATALOG(pg_collation,3456,CollationRelationId)
 	Oid			collnamespace;	/* OID of namespace containing collation */
 	Oid			collowner;		/* owner of collation */
 	char		collprovider;	/* see constants below */
+	bool		collisdeterministic BKI_DEFAULT(t);
 	int32		collencoding;	/* encoding for this collation; -1 = "all" */
 	NameData	collcollate;	/* LC_COLLATE setting */
 	NameData	collctype;		/* LC_CTYPE setting */
@@ -61,6 +62,7 @@ typedef FormData_pg_collation *Form_pg_collation;
 extern Oid CollationCreate(const char *collname, Oid collnamespace,
 				Oid collowner,
 				char collprovider,
+				bool collisdeterministic,
 				int32 collencoding,
 				const char *collcollate, const char *collctype,
 				const char *collversion,
diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h
index 9003f2ce58..0cf7aa3495 100644
--- a/src/include/executor/executor.h
+++ b/src/include/executor/executor.h
@@ -111,6 +111,7 @@ extern ExprState *execTuplesMatchPrepare(TupleDesc desc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqOperators,
+					   const Oid *collations,
 					   PlanState *parent);
 extern void execTuplesHashPrepare(int numCols,
 					  const Oid *eqOperators,
@@ -121,6 +122,7 @@ extern TupleHashTable BuildTupleHashTable(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext tablecxt,
 					MemoryContext tempcxt, bool use_variable_hash_iv);
@@ -129,6 +131,7 @@ extern TupleHashTable BuildTupleHashTableExt(PlanState *parent,
 					int numCols, AttrNumber *keyColIdx,
 					const Oid *eqfuncoids,
 					FmgrInfo *hashfunctions,
+					Oid *collations,
 					long nbuckets, Size additionalsize,
 					MemoryContext metacxt,
 					MemoryContext tablecxt,
@@ -257,6 +260,7 @@ extern ExprState *ExecBuildGroupingEqual(TupleDesc ldesc, TupleDesc rdesc,
 					   int numCols,
 					   const AttrNumber *keyColIdx,
 					   const Oid *eqfunctions,
+					   const Oid *collations,
 					   PlanState *parent);
 extern ProjectionInfo *ExecBuildProjectionInfo(List *targetList,
 						ExprContext *econtext,
diff --git a/src/include/executor/hashjoin.h b/src/include/executor/hashjoin.h
index e7bf158c1b..2c94b926d3 100644
--- a/src/include/executor/hashjoin.h
+++ b/src/include/executor/hashjoin.h
@@ -337,6 +337,7 @@ typedef struct HashJoinTableData
 	FmgrInfo   *outer_hashfunctions;	/* lookup data for hash functions */
 	FmgrInfo   *inner_hashfunctions;	/* lookup data for hash functions */
 	bool	   *hashStrict;		/* is each hash join operator strict? */
+	Oid		   *collations;
 
 	Size		spaceUsed;		/* memory space currently used by tuples */
 	Size		spaceAllowed;	/* upper limit for space used */
diff --git a/src/include/executor/nodeHash.h b/src/include/executor/nodeHash.h
index 1309b32b90..1233766023 100644
--- a/src/include/executor/nodeHash.h
+++ b/src/include/executor/nodeHash.h
@@ -24,7 +24,7 @@ extern Node *MultiExecHash(HashState *node);
 extern void ExecEndHash(HashState *node);
 extern void ExecReScanHash(HashState *node);
 
-extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators,
+extern HashJoinTable ExecHashTableCreate(HashState *state, List *hashOperators, List *hashCollations,
 					bool keepNulls);
 extern void ExecParallelHashTableAlloc(HashJoinTable hashtable,
 						   int batchno);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 62eb1a06ee..869c303e15 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -693,6 +693,7 @@ typedef struct TupleHashTableData
 	AttrNumber *keyColIdx;		/* attr numbers of key columns */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	ExprState  *tab_eq_func;	/* comparator for table datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	MemoryContext tablecxt;		/* memory context containing table */
 	MemoryContext tempcxt;		/* context for function evaluations */
 	Size		entrysize;		/* actual size to make each hash entry */
@@ -862,6 +863,7 @@ typedef struct SubPlanState
 	AttrNumber *keyColIdx;		/* control data for hash tables */
 	Oid		   *tab_eq_funcoids;	/* equality func oids for table
 									 * datatype(s) */
+	Oid		   *tab_collations;	/* collations for hash and comparison */
 	FmgrInfo   *tab_hash_funcs; /* hash functions for table datatype(s) */
 	FmgrInfo   *tab_eq_funcs;	/* equality functions for table datatype(s) */
 	FmgrInfo   *lhs_hash_funcs; /* hash functions for lefthand datatype(s) */
@@ -1872,6 +1874,7 @@ typedef struct HashJoinState
 	List	   *hj_OuterHashKeys;	/* list of ExprState nodes */
 	List	   *hj_InnerHashKeys;	/* list of ExprState nodes */
 	List	   *hj_HashOperators;	/* list of operator OIDs */
+	List	   *hj_Collations;
 	HashJoinTable hj_HashTable;
 	uint32		hj_CurHashValue;
 	int			hj_CurBucketNo;
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index d66a187a53..24740c31e3 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -297,6 +297,7 @@ typedef struct RecursiveUnion
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	long		numGroups;		/* estimated number of groups in input */
 } RecursiveUnion;
 
@@ -773,6 +774,7 @@ typedef struct Group
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 } Group;
 
 /* ---------------
@@ -797,6 +799,7 @@ typedef struct Agg
 	int			numCols;		/* number of grouping columns */
 	AttrNumber *grpColIdx;		/* their indexes in the target list */
 	Oid		   *grpOperators;	/* equality operators to compare with */
+	Oid		   *grpCollations;
 	long		numGroups;		/* estimated number of groups in input */
 	Bitmapset  *aggParams;		/* IDs of Params used in Aggref inputs */
 	/* Note: planner provides numGroups & aggParams only in HASHED/MIXED case */
@@ -815,9 +818,11 @@ typedef struct WindowAgg
 	int			partNumCols;	/* number of columns in partition clause */
 	AttrNumber *partColIdx;		/* their indexes in the target list */
 	Oid		   *partOperators;	/* equality operators for partition columns */
+	Oid		   *partCollations;	/* collations for partition columns */
 	int			ordNumCols;		/* number of columns in ordering clause */
 	AttrNumber *ordColIdx;		/* their indexes in the target list */
 	Oid		   *ordOperators;	/* equality operators for ordering columns */
+	Oid		   *ordCollations;	/* collations for ordering columns */
 	int			frameOptions;	/* frame_clause options, see WindowDef */
 	Node	   *startOffset;	/* expression for starting bound, if any */
 	Node	   *endOffset;		/* expression for ending bound, if any */
@@ -839,6 +844,7 @@ typedef struct Unique
 	int			numCols;		/* number of columns to check for uniqueness */
 	AttrNumber *uniqColIdx;		/* their indexes in the target list */
 	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Unique;
 
 /* ------------
@@ -913,6 +919,7 @@ typedef struct SetOp
 								 * duplicate-ness */
 	AttrNumber *dupColIdx;		/* their indexes in the target list */
 	Oid		   *dupOperators;	/* equality operators to compare with */
+	Oid		   *dupCollations;
 	AttrNumber	flagColIdx;		/* where is the flag column, if any */
 	int			firstFlag;		/* flag value for first input relation */
 	long		numGroups;		/* estimated number of groups in input */
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index 3bbdb5e2f7..b093a3c8ac 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -53,7 +53,7 @@ extern bool is_projection_capable_plan(Plan *plan);
 extern Sort *make_sort_from_sortclauses(List *sortcls, Plan *lefttree);
 extern Agg *make_agg(List *tlist, List *qual,
 		 AggStrategy aggstrategy, AggSplit aggsplit,
-		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
+		 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 		 List *groupingSets, List *chain,
 		 double dNumGroups, Plan *lefttree);
 extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
diff --git a/src/include/optimizer/tlist.h b/src/include/optimizer/tlist.h
index 58db79203b..46d614f4fb 100644
--- a/src/include/optimizer/tlist.h
+++ b/src/include/optimizer/tlist.h
@@ -32,6 +32,7 @@ extern bool tlist_same_collations(List *tlist, List *colCollations, bool junkOK)
 extern void apply_tlist_labeling(List *dest_tlist, List *src_tlist);
 
 extern Oid *extract_grouping_ops(List *groupClause);
+extern Oid *extract_grouping_collations(List *groupClause, List *tlist);
 extern AttrNumber *extract_grouping_cols(List *groupClause, List *tlist);
 extern bool grouping_is_sortable(List *groupClause);
 extern bool grouping_is_hashable(List *groupClause);
diff --git a/src/include/partitioning/partbounds.h b/src/include/partitioning/partbounds.h
index b1ae39ad63..683e1574ea 100644
--- a/src/include/partitioning/partbounds.h
+++ b/src/include/partitioning/partbounds.h
@@ -77,6 +77,7 @@ typedef struct PartitionBoundInfoData
 
 extern int	get_hash_partition_greatest_modulus(PartitionBoundInfo b);
 extern uint64 compute_partition_hash_value(int partnatts, FmgrInfo *partsupfunc,
+							 Oid *partcollation,
 							 Datum *values, bool *isnull);
 extern List *get_qual_from_partbound(Relation rel, Relation parent,
 						PartitionBoundSpec *spec);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 16b0b1d2dc..b9a9ecb7cc 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -90,6 +90,7 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 					  Oid *typid, int32 *typmod, Oid *collid);
 extern char *get_collation_name(Oid colloid);
+extern bool get_collation_isdeterministic(Oid colloid);
 extern char *get_constraint_name(Oid conoid);
 extern char *get_language_name(Oid langoid, bool missing_ok);
 extern Oid	get_opclass_family(Oid opclass);
diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h
index 606952afd7..a342a62549 100644
--- a/src/include/utils/pg_locale.h
+++ b/src/include/utils/pg_locale.h
@@ -82,6 +82,7 @@ extern void cache_locale_time(void);
 struct pg_locale_struct
 {
 	char		provider;
+	bool		deterministic;
 	union
 	{
 #ifdef HAVE_LOCALE_T
diff --git a/src/test/regress/expected/collate.icu.utf8.out b/src/test/regress/expected/collate.icu.utf8.out
index 4b94921cf8..b05baf1b76 100644
--- a/src/test/regress/expected/collate.icu.utf8.out
+++ b/src/test/regress/expected/collate.icu.utf8.out
@@ -1139,6 +1139,716 @@ SELECT 'A-21' > 'A-123' COLLATE "und-x-icu", 'A-21' < 'A-123' COLLATE testcoll_n
 
 CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
 ERROR:  could not open collator for locale "@colNumeric=lower": U_ILLEGAL_ARGUMENT_ERROR
+-- nondeterministic collations
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+ a |  b  
+---+-----
+ 1 | äbc
+(1 row)
+
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+ a |  b  
+---+-----
+ 1 | äbc
+ 2 | äbc
+(2 rows)
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | f
+(1 row)
+
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+ ?column? | ?column? 
+----------+----------
+ t        | t
+(1 row)
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3cs WHERE x = 'abc';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x <> 'abc';
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test3cs WHERE x ~ 'a';
+  x  
+-----
+ abc
+(1 row)
+
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+  x  
+-----
+ ghi
+(1 row)
+
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+  x  
+-----
+ abc
+ def
+(2 rows)
+
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+  x  
+-----
+ abc
+ ABC
+ def
+ ghi
+(4 rows)
+
+SELECT count(DISTINCT x) FROM test3cs;
+ count 
+-------
+     4
+(1 row)
+
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     1
+ ABC |     1
+ def |     1
+ ghi |     1
+(4 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    2
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+ string_to_array 
+-----------------
+ {ABC,DEF,GHI}
+(1 row)
+
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+   string_to_array   
+---------------------
+ {A,B,C,D,E,F,G,H,I}
+(1 row)
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+CREATE INDEX ON test3ci (x text_pattern_ops);  -- error
+ERROR:  nondeterministic collations are not supported for operator class "text_pattern_ops"
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3ci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3ci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3ci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3ci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1ci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+ERROR:  could not create unique index "test3ci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+CREATE INDEX ON test3bpci (x bpchar_pattern_ops);  -- error
+ERROR:  nondeterministic collations are not supported for operator class "bpchar_pattern_ops"
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+SELECT x FROM test3bpci WHERE x = 'abc';
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x <> 'abc';
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+ERROR:  nondeterministic collations are not supported for ILIKE
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test3bpci WHERE x ~ 'a';
+ERROR:  nondeterministic collations are not supported for regular expressions
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+  x  
+-----
+ ABC
+ def
+ ghi
+(3 rows)
+
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+  x  
+-----
+ ghi
+ abc
+(2 rows)
+
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+  x  
+-----
+ ghi
+ ABC
+(2 rows)
+
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+  x  
+-----
+ def
+(1 row)
+
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+ x 
+---
+(0 rows)
+
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT count(DISTINCT x) FROM test3bpci;
+ count 
+-------
+     3
+(1 row)
+
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+  x  | count 
+-----+-------
+ abc |     2
+ def |     1
+ ghi |     1
+(3 rows)
+
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+  x  | row_number | rank 
+-----+------------+------
+ abc |          1 |    1
+ ABC |          2 |    1
+ def |          3 |    3
+ ghi |          4 |    4
+(4 rows)
+
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+ERROR:  duplicate key value violates unique constraint "test1bpci_x_idx"
+DETAIL:  Key (x)=(ABC) already exists.
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+ERROR:  could not create unique index "test3bpci_x_idx"
+DETAIL:  Key (x)=(abc) is duplicated.
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+ERROR:  nondeterministic collations are not supported for substring searches
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+    string_to_array     
+------------------------
+ {A,NULL,C,D,E,F,G,H,I}
+(1 row)
+
+-- This tests the issue described in match_pattern_prefix().  In the
+-- absence of that check, the case_insensitive tests below would
+-- return no rows where they should logically return one.
+CREATE TABLE test4c (x text COLLATE "C");
+INSERT INTO test4c VALUES ('abc');
+CREATE INDEX ON test4c (x);
+SET enable_seqscan = off;
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_sensitive;  -- ok, no rows
+ x 
+---
+(0 rows)
+
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_sensitive;  -- ok, no rows
+ x 
+---
+(0 rows)
+
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_insensitive;  -- error
+ERROR:  nondeterministic collations are not supported for LIKE
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_insensitive;  -- error
+ERROR:  nondeterministic collations are not supported for LIKE
+RESET enable_seqscan;
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+ ?column? 
+----------
+ f
+(1 row)
+
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+ ?column? 
+----------
+ t
+(1 row)
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+ relname  
+----------
+ pg_class
+(1 row)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+ typname 
+---------
+ int4
+ int8
+(2 rows)
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ B  | 
+(2 rows)
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+ a |  b   
+---+------
+ 1 | cote
+ 2 | côte
+ 3 | coté
+ 4 | côté
+(4 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+ a | b 
+---+---
+(0 rows)
+
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+ a |  b   
+---+------
+ 1 | cote
+(1 row)
+
+-- foreign keys (should use collation of primary key)
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+INSERT INTO test10fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test10pk".
+SELECT * FROM test10pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+ERROR:  insert or update on table "test10fk" violates foreign key constraint "test10fk_x_fkey"
+DETAIL:  Key (x)=(ABC) is not present in table "test10pk".
+SELECT * FROM test10fk;
+  x  
+-----
+ abc
+(1 row)
+
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test10fk;
+ x 
+---
+(0 rows)
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+ERROR:  insert or update on table "test11fk" violates foreign key constraint "test11fk_x_fkey"
+DETAIL:  Key (x)=(xyz) is not present in table "test11pk".
+SELECT * FROM test11pk;
+  x  
+-----
+ abc
+ def
+ ghi
+(3 rows)
+
+SELECT * FROM test11fk;
+  x  
+-----
+ abc
+ ABC
+(2 rows)
+
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+  x  
+-----
+ ABC
+ ABC
+(2 rows)
+
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+  x  
+-----
+ def
+ ghi
+(2 rows)
+
+SELECT * FROM test11fk;
+ x 
+---
+(0 rows)
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+ ?column? 
+----------
+ t
+(1 row)
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+ ?column? 
+----------
+ t
+(1 row)
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.linux.utf8.out b/src/test/regress/expected/collate.linux.utf8.out
index d33f04a3b5..6b245a7f28 100644
--- a/src/test/regress/expected/collate.linux.utf8.out
+++ b/src/test/regress/expected/collate.linux.utf8.out
@@ -1117,6 +1117,11 @@ select textrange_en_us('A','Z') @> 'b'::text;
 
 drop type textrange_c;
 drop type textrange_en_us;
+-- nondeterministic collations
+-- (not supported with libc provider)
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+ERROR:  nondeterministic collations not supported with this provider
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/expected/collate.out b/src/test/regress/expected/collate.out
index fcbe3a5cc8..dbfa5c9348 100644
--- a/src/test/regress/expected/collate.out
+++ b/src/test/regress/expected/collate.out
@@ -498,6 +498,21 @@ SELECT a, b, a < b as lt FROM
  A | b | t
 (2 rows)
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+ERROR:  could not determine which collation to use for string hashing
+HINT:  Use the COLLATE clause to set the collation explicitly.
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
+ a | x | y 
+---+---+---
+(0 rows)
+
 -- casting
 SELECT CAST('42' AS text COLLATE "C");
 ERROR:  syntax error at or near "COLLATE"
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index fe5fc64480..4a54104182 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,25 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
   1 |   
 (2 rows)
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+ f1 | f2 
+----+----
+ b  | a
+ b  | 
+(2 rows)
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/regress/sql/collate.icu.utf8.sql b/src/test/regress/sql/collate.icu.utf8.sql
index 73fb1232a7..67685f6a9d 100644
--- a/src/test/regress/sql/collate.icu.utf8.sql
+++ b/src/test/regress/sql/collate.icu.utf8.sql
@@ -446,6 +446,256 @@ CREATE COLLATION testcoll_numeric (provider = icu, locale = '@colNumeric=yes');
 CREATE COLLATION testcoll_error1 (provider = icu, locale = '@colNumeric=lower');
 
 
+-- nondeterministic collations
+
+CREATE COLLATION ctest_det (provider = icu, locale = 'und', deterministic = true);
+CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false);
+
+CREATE TABLE test6 (a int, b text);
+-- same string in different normal forms
+INSERT INTO test6 VALUES (1, U&'\00E4bc');
+INSERT INTO test6 VALUES (2, U&'\0061\0308bc');
+SELECT * FROM test6;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_det;
+SELECT * FROM test6 WHERE b = 'äbc' COLLATE ctest_nondet;
+
+CREATE COLLATION case_sensitive (provider = icu, locale = 'und');
+CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
+
+SELECT 'abc' <= 'ABC' COLLATE case_sensitive, 'abc' >= 'ABC' COLLATE case_sensitive;
+SELECT 'abc' <= 'ABC' COLLATE case_insensitive, 'abc' >= 'ABC' COLLATE case_insensitive;
+
+CREATE TABLE test1cs (x text COLLATE case_sensitive);
+CREATE TABLE test2cs (x text COLLATE case_sensitive);
+CREATE TABLE test3cs (x text COLLATE case_sensitive);
+INSERT INTO test1cs VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2cs VALUES ('ABC'), ('ghi');
+INSERT INTO test3cs VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3cs WHERE x = 'abc';
+SELECT x FROM test3cs WHERE x <> 'abc';
+SELECT x FROM test3cs WHERE x LIKE 'a%';
+SELECT x FROM test3cs WHERE x ILIKE 'a%';
+SELECT x FROM test3cs WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3cs WHERE x ~ 'a';
+SELECT x FROM test1cs UNION SELECT x FROM test2cs ORDER BY x;
+SELECT x FROM test2cs UNION SELECT x FROM test1cs ORDER BY x;
+SELECT x FROM test1cs INTERSECT SELECT x FROM test2cs;
+SELECT x FROM test2cs INTERSECT SELECT x FROM test1cs;
+SELECT x FROM test1cs EXCEPT SELECT x FROM test2cs;
+SELECT x FROM test2cs EXCEPT SELECT x FROM test1cs;
+SELECT DISTINCT x FROM test3cs ORDER BY x;
+SELECT count(DISTINCT x) FROM test3cs;
+SELECT x, count(*) FROM test3cs GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3cs ORDER BY x;
+CREATE UNIQUE INDEX ON test1cs (x);  -- ok
+INSERT INTO test1cs VALUES ('ABC');  -- ok
+CREATE UNIQUE INDEX ON test3cs (x);  -- ok
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_sensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_sensitive, NULL, 'b');
+
+CREATE TABLE test1ci (x text COLLATE case_insensitive);
+CREATE TABLE test2ci (x text COLLATE case_insensitive);
+CREATE TABLE test3ci (x text COLLATE case_insensitive);
+CREATE INDEX ON test3ci (x text_pattern_ops);  -- error
+INSERT INTO test1ci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2ci VALUES ('ABC'), ('ghi');
+INSERT INTO test3ci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3ci WHERE x = 'abc';
+SELECT x FROM test3ci WHERE x <> 'abc';
+SELECT x FROM test3ci WHERE x LIKE 'a%';
+SELECT x FROM test3ci WHERE x ILIKE 'a%';
+SELECT x FROM test3ci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3ci WHERE x ~ 'a';
+SELECT x FROM test1ci UNION SELECT x FROM test2ci ORDER BY x;
+SELECT x FROM test2ci UNION SELECT x FROM test1ci ORDER BY x;
+SELECT x FROM test1ci INTERSECT SELECT x FROM test2ci;
+SELECT x FROM test2ci INTERSECT SELECT x FROM test1ci;
+SELECT x FROM test1ci EXCEPT SELECT x FROM test2ci;
+SELECT x FROM test2ci EXCEPT SELECT x FROM test1ci;
+SELECT DISTINCT x FROM test3ci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3ci;
+SELECT x, count(*) FROM test3ci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3ci ORDER BY x;
+CREATE UNIQUE INDEX ON test1ci (x);  -- ok
+INSERT INTO test1ci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3ci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI' COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI' COLLATE case_insensitive, NULL, 'b');
+
+-- bpchar
+CREATE TABLE test1bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test2bpci (x char(3) COLLATE case_insensitive);
+CREATE TABLE test3bpci (x char(3) COLLATE case_insensitive);
+CREATE INDEX ON test3bpci (x bpchar_pattern_ops);  -- error
+INSERT INTO test1bpci VALUES ('abc'), ('def'), ('ghi');
+INSERT INTO test2bpci VALUES ('ABC'), ('ghi');
+INSERT INTO test3bpci VALUES ('abc'), ('ABC'), ('def'), ('ghi');
+
+SELECT x FROM test3bpci WHERE x = 'abc';
+SELECT x FROM test3bpci WHERE x <> 'abc';
+SELECT x FROM test3bpci WHERE x LIKE 'a%';
+SELECT x FROM test3bpci WHERE x ILIKE 'a%';
+SELECT x FROM test3bpci WHERE x SIMILAR TO 'a%';
+SELECT x FROM test3bpci WHERE x ~ 'a';
+SELECT x FROM test1bpci UNION SELECT x FROM test2bpci ORDER BY x;
+SELECT x FROM test2bpci UNION SELECT x FROM test1bpci ORDER BY x;
+SELECT x FROM test1bpci INTERSECT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci INTERSECT SELECT x FROM test1bpci;
+SELECT x FROM test1bpci EXCEPT SELECT x FROM test2bpci;
+SELECT x FROM test2bpci EXCEPT SELECT x FROM test1bpci;
+SELECT DISTINCT x FROM test3bpci ORDER BY x;
+SELECT count(DISTINCT x) FROM test3bpci;
+SELECT x, count(*) FROM test3bpci GROUP BY x ORDER BY x;
+SELECT x, row_number() OVER (ORDER BY x), rank() OVER (ORDER BY x) FROM test3bpci ORDER BY x;
+CREATE UNIQUE INDEX ON test1bpci (x);  -- ok
+INSERT INTO test1bpci VALUES ('ABC');  -- error
+CREATE UNIQUE INDEX ON test3bpci (x);  -- error
+SELECT string_to_array('ABC,DEF,GHI'::char(11) COLLATE case_insensitive, ',', 'abc');
+SELECT string_to_array('ABCDEFGHI'::char(9) COLLATE case_insensitive, NULL, 'b');
+
+-- This tests the issue described in match_pattern_prefix().  In the
+-- absence of that check, the case_insensitive tests below would
+-- return no rows where they should logically return one.
+CREATE TABLE test4c (x text COLLATE "C");
+INSERT INTO test4c VALUES ('abc');
+CREATE INDEX ON test4c (x);
+SET enable_seqscan = off;
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_sensitive;  -- ok, no rows
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_sensitive;  -- ok, no rows
+SELECT x FROM test4c WHERE x LIKE 'ABC' COLLATE case_insensitive;  -- error
+SELECT x FROM test4c WHERE x LIKE 'ABC%' COLLATE case_insensitive;  -- error
+RESET enable_seqscan;
+
+-- Unicode special case: different variants of Greek lower case sigma.
+-- A naive implementation like citext that just does lower(x) =
+-- lower(y) will do the wrong thing here, because lower('Σ') is 'σ'
+-- but upper('ς') is 'Σ'.
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_sensitive;
+SELECT 'ὀδυσσεύς' = 'ὈΔΥΣΣΕΎΣ' COLLATE case_insensitive;
+
+-- name vs. text comparison operators
+SELECT relname FROM pg_class WHERE relname = 'PG_CLASS'::text COLLATE case_insensitive;
+SELECT relname FROM pg_class WHERE 'PG_CLASS'::text = relname COLLATE case_insensitive;
+
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND typname <> 'INT2'::text COLLATE case_insensitive;
+SELECT typname FROM pg_type WHERE typname LIKE 'int_' AND 'INT2'::text <> typname COLLATE case_insensitive;;
+
+-- test case adapted from subselect.sql
+CREATE TEMP TABLE outer_text (f1 text COLLATE case_insensitive, f2 text);
+INSERT INTO outer_text VALUES ('a', 'a');
+INSERT INTO outer_text VALUES ('b', 'a');
+INSERT INTO outer_text VALUES ('A', NULL);
+INSERT INTO outer_text VALUES ('B', NULL);
+
+CREATE TEMP TABLE inner_text (c1 text COLLATE case_insensitive, c2 text);
+INSERT INTO inner_text VALUES ('a', NULL);
+
+SELECT * FROM outer_text WHERE (f1, f2) NOT IN (SELECT * FROM inner_text);
+
+-- accents
+CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
+
+CREATE TABLE test4 (a int, b text);
+INSERT INTO test4 VALUES (1, 'cote'), (2, 'côte'), (3, 'coté'), (4, 'côté');
+SELECT * FROM test4 WHERE b = 'cote';
+SELECT * FROM test4 WHERE b = 'cote' COLLATE ignore_accents;
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE ignore_accents;  -- still case-sensitive
+SELECT * FROM test4 WHERE b = 'Cote' COLLATE case_insensitive;
+
+-- foreign keys (should use collation of primary key)
+
+-- PK is case-sensitive, FK is case-insensitive
+CREATE TABLE test10pk (x text COLLATE case_sensitive PRIMARY KEY);
+INSERT INTO test10pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test10fk VALUES ('abc');  -- ok
+INSERT INTO test10fk VALUES ('ABC');  -- error
+INSERT INTO test10fk VALUES ('xyz');  -- error
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+-- restrict update even though the values are "equal" in the FK table
+UPDATE test10fk SET x = 'ABC' WHERE x = 'abc';  -- error
+SELECT * FROM test10fk;
+DELETE FROM test10pk WHERE x = 'abc';
+SELECT * FROM test10pk;
+SELECT * FROM test10fk;
+
+-- PK is case-insensitive, FK is case-sensitive
+CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
+INSERT INTO test11pk VALUES ('abc'), ('def'), ('ghi');
+CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);
+INSERT INTO test11fk VALUES ('abc');  -- ok
+INSERT INTO test11fk VALUES ('ABC');  -- ok
+INSERT INTO test11fk VALUES ('xyz');  -- error
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+-- cascade update even though the values are "equal" in the PK table
+UPDATE test11pk SET x = 'ABC' WHERE x = 'abc';
+SELECT * FROM test11fk;
+DELETE FROM test11pk WHERE x = 'abc';
+SELECT * FROM test11pk;
+SELECT * FROM test11fk;
+
+-- partitioning
+CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');
+INSERT INTO test20 VALUES (1, 'abc');
+INSERT INTO test20 VALUES (2, 'ABC');
+SELECT * FROM test20_1;
+
+CREATE TABLE test21 (a int, b text COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test21_1 PARTITION OF test21 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test21 VALUES (1, 'abc');
+INSERT INTO test21 VALUES (2, 'ABC');
+SELECT * FROM test21_1;
+
+CREATE TABLE test22 (a int, b text COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test22_0 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test22_1 PARTITION OF test22 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test22 VALUES (1, 'def');
+INSERT INTO test22 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test22_0) = (SELECT count(*) FROM test22_1);
+
+CREATE TABLE test23 (a int, b text COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test23_0 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test23_1 PARTITION OF test23 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test23 VALUES (1, 'def');
+INSERT INTO test23 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test23_0) <> (SELECT count(*) FROM test23_1);
+
+CREATE TABLE test30 (a int, b char(3) COLLATE case_insensitive) PARTITION BY LIST (b);
+CREATE TABLE test30_1 PARTITION OF test30 FOR VALUES IN ('abc');
+INSERT INTO test30 VALUES (1, 'abc');
+INSERT INTO test30 VALUES (2, 'ABC');
+SELECT * FROM test30_1;
+
+CREATE TABLE test31 (a int, b char(3) COLLATE case_insensitive) PARTITION BY RANGE (b);
+CREATE TABLE test31_1 PARTITION OF test31 FOR VALUES FROM ('ABC') TO ('DEF');
+INSERT INTO test31 VALUES (1, 'abc');
+INSERT INTO test31 VALUES (2, 'ABC');
+SELECT * FROM test31_1;
+
+CREATE TABLE test32 (a int, b char(3) COLLATE case_sensitive) PARTITION BY HASH (b);
+CREATE TABLE test32_0 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test32_1 PARTITION OF test32 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test32 VALUES (1, 'def');
+INSERT INTO test32 VALUES (2, 'DEF');
+-- they end up in different partitions
+SELECT (SELECT count(*) FROM test32_0) = (SELECT count(*) FROM test32_1);
+
+CREATE TABLE test33 (a int, b char(3) COLLATE case_insensitive) PARTITION BY HASH (b);
+CREATE TABLE test33_0 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 0);
+CREATE TABLE test33_1 PARTITION OF test33 FOR VALUES WITH (MODULUS 2, REMAINDER 1);
+INSERT INTO test33 VALUES (1, 'def');
+INSERT INTO test33 VALUES (2, 'DEF');
+-- they end up in the same partition (but it's platform-dependent which one)
+SELECT (SELECT count(*) FROM test33_0) <> (SELECT count(*) FROM test33_1);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.linux.utf8.sql b/src/test/regress/sql/collate.linux.utf8.sql
index e882153244..4ca02b821d 100644
--- a/src/test/regress/sql/collate.linux.utf8.sql
+++ b/src/test/regress/sql/collate.linux.utf8.sql
@@ -428,6 +428,13 @@ CREATE INDEX collate_dep_test4i ON collate_dep_test4t (b COLLATE test0);
 drop type textrange_en_us;
 
 
+-- nondeterministic collations
+-- (not supported with libc provider)
+
+CREATE COLLATION ctest_det (locale = 'en_US.utf8', deterministic = true);
+CREATE COLLATION ctest_nondet (locale = 'en_US.utf8', deterministic = false);
+
+
 -- cleanup
 SET client_min_messages TO warning;
 DROP SCHEMA collate_tests CASCADE;
diff --git a/src/test/regress/sql/collate.sql b/src/test/regress/sql/collate.sql
index 4ddde95a5e..cb2bc22155 100644
--- a/src/test/regress/sql/collate.sql
+++ b/src/test/regress/sql/collate.sql
@@ -163,6 +163,11 @@ CREATE TABLE test_u AS SELECT a, b FROM collate_test1 UNION ALL SELECT a, b FROM
 SELECT a, b, a < b as lt FROM
   (VALUES ('a', 'B'), ('A', 'b' COLLATE "C")) v(a,b);
 
+-- collation mismatch in subselects
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y, x FROM collate_test10);
+-- now it works with overrides
+SELECT * FROM collate_test10 WHERE (x COLLATE "POSIX", y COLLATE "C") NOT IN (SELECT y, x FROM collate_test10);
+SELECT * FROM collate_test10 WHERE (x, y) NOT IN (SELECT y COLLATE "C", x COLLATE "POSIX" FROM collate_test10);
 
 -- casting
 
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index b5931ee700..856bbff732 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,23 @@ CREATE VIEW orders_view AS
 
 select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
 
+--
+-- Similar test case using text that verifies that collation
+-- information is passed through by execTuplesEqual() in nodeSubplan.c
+-- (otherwise it would error in texteq())
+--
+
+create temp table outer_text (f1 text, f2 text);
+insert into outer_text values ('a', 'a');
+insert into outer_text values ('b', 'a');
+insert into outer_text values ('a', null);
+insert into outer_text values ('b', null);
+
+create temp table inner_text (c1 text, c2 text);
+insert into inner_text values ('a', null);
+
+select * from outer_text where (f1, f2) not in (select * from inner_text);
+
 --
 -- Test case for premature memory release during hashing of subplan output
 --
diff --git a/src/test/subscription/Makefile b/src/test/subscription/Makefile
index e7bbb454c7..4378819530 100644
--- a/src/test/subscription/Makefile
+++ b/src/test/subscription/Makefile
@@ -15,6 +15,8 @@ include $(top_builddir)/src/Makefile.global
 
 EXTRA_INSTALL = contrib/hstore
 
+export with_icu
+
 check:
 	$(prove_check)
 
diff --git a/src/test/subscription/t/012_collation.pl b/src/test/subscription/t/012_collation.pl
new file mode 100644
index 0000000000..6c480de9c1
--- /dev/null
+++ b/src/test/subscription/t/012_collation.pl
@@ -0,0 +1,103 @@
+# Test collations, in particular nondeterministic ones
+# (only works with ICU)
+use strict;
+use warnings;
+use PostgresNode;
+use TestLib;
+use Test::More;
+
+if ($ENV{with_icu} eq 'yes')
+{
+	plan tests => 2;
+}
+else
+{
+	plan skip_all => 'ICU not supported by this build';
+}
+
+my $node_publisher = get_new_node('publisher');
+$node_publisher->init(allows_streaming => 'logical');
+$node_publisher->start;
+
+my $node_subscriber = get_new_node('subscriber');
+$node_subscriber->init(allows_streaming => 'logical');
+$node_subscriber->start;
+
+my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
+
+# Test plan: Create a table with a nondeterministic collation in the
+# primary key column.  Pre-insert rows on the publisher and subscriber
+# that are collation-wise equal but byte-wise different.  (We use a
+# string in different normal forms for that.)  Set up publisher and
+# subscriber.  Update the row on the publisher, but don't change the
+# primary key column.  The subscriber needs to find the row to be
+# updated using the nondeterministic collation semantics.  We need to
+# test for both a replica identity index and for replica identity
+# full, since those have different code paths internally.
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE COLLATION ctest_nondet (provider = icu, locale = 'und', deterministic = false)});
+
+# table with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text PRIMARY KEY, b text)});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab1 (a text COLLATE ctest_nondet PRIMARY KEY, b text)});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab1 VALUES (U&'\0061\0308bc', 'foo')});
+
+# table with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text, b text)});
+$node_publisher->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_publisher->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\00E4bc', 'foo')});
+
+$node_subscriber->safe_psql('postgres',
+	q{CREATE TABLE tab2 (a text COLLATE ctest_nondet, b text)});
+$node_subscriber->safe_psql('postgres',
+	q{ALTER TABLE tab2 REPLICA IDENTITY FULL});
+
+$node_subscriber->safe_psql('postgres',
+	q{INSERT INTO tab2 VALUES (U&'\0061\0308bc', 'foo')});
+
+# set up publication, subscription
+
+$node_publisher->safe_psql('postgres',
+	q{CREATE PUBLICATION pub1 FOR ALL TABLES});
+
+$node_subscriber->safe_psql('postgres',
+	qq{CREATE SUBSCRIPTION sub1 CONNECTION '$publisher_connstr' PUBLICATION pub1 WITH (copy_data = false)});
+
+$node_publisher->wait_for_catchup('sub1');
+
+# test with replica identity index
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab1 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab1}),
+   qq(bar),
+  'update with primary key with nondeterministic collation');
+
+# test with replica identity full
+
+$node_publisher->safe_psql('postgres',
+	q{UPDATE tab2 SET b = 'bar' WHERE b = 'foo'});
+
+$node_publisher->wait_for_catchup('sub1');
+
+is($node_subscriber->safe_psql('postgres', q{SELECT b FROM tab2}),
+   qq(bar),
+  'update with replica identity full with nondeterministic collation');

base-commit: 4178d8b91cb943b422d1837b4b7798576d88995a
-- 
2.21.0