tablecmds.c/MergeAttributes() cleanup

From ce3a0ad830ac167c01809a2288e4a9b9a9de62de Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 10/10] MergeAttributes: convert pg_attribute back to
 ColumnDef before comparing

MergeAttributes() has a loop to merge multiple inheritance parents
into a column column definition.  The merged-so-far definition is
stored in a ColumnDef node.  If we have to merge columns from multiple
inheritance parents (if the name matches), then we have to check
whether various column properties (type, collation, etc.) match.  The
current code extracts the pg_attribute value of the
currently-considered inheritance parent and compares it against the
merge-so-far ColumnDef value.  If the currently considered column
doesn't match any previously inherited column, we make a new ColumnDef
node from the pg_attribute information and add it to the column list.

This patch rearranges this so that we create the ColumnDef node first
in either case.  Then the code that checks the column properties for
compatibility compares ColumnDef against ColumnDef (instead of
ColumnDef against pg_attribute).  This matches the code more symmetric
and easier to follow.  Also, later in MergeAttributes(), there is a
similar but separate loop that merges the new local column definition
with the combination of the inheritance parents established in the
first loop.  That comparison is already ColumnDef-vs-ColumnDef.  With
this change, but of these can use similar looking logic.  (A future
project might be to extract these two sets of code into a common
routine that encodes all the knowledge of whether two column
definitions are compatible.  But this isn't currently straightforward
because we want to give different error messages in the two cases.)
Furthermore, by avoiding the use of Form_pg_attribute here, we make it
easier to make changes in the pg_attribute layout without having to
worry about the local needs of tablecmds.c.

Because MergeAttributes() is hugely long, it's sometimes hard to know
where in the function you are currently looking.  To help with that, I
also renamed some variables to make it clearer where you are currently
looking.  The first look is "prev" vs. "new", the second loop is "inh"
vs. "new".
---
 src/backend/commands/tablecmds.c | 181 ++++++++++++++++---------------
 1 file changed, 94 insertions(+), 87 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 1c70cf7af5..16e4a9e5fd 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2698,7 +2698,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
-			ColumnDef  *def;
+			ColumnDef  *newdef;
+			ColumnDef  *savedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2707,14 +2708,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Create new column definition
+			 */
+			newdef = makeColumnDef(attributeName, attribute->atttypid,
+								   attribute->atttypmod, attribute->attcollation);
+			newdef->storage = attribute->attstorage;
+			newdef->generated = attribute->attgenerated;
+			if (CompressionMethodIsValid(attribute->attcompression))
+				newdef->compression =
+					pstrdup(GetCompressionMethodName(attribute->attcompression));
+
+			/*
+			 * Does it match some previously considered column from another
+			 * parent?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				Oid			defTypeId;
-				int32		deftypmod;
-				Oid			defCollId;
+				ColumnDef  *prevdef;
+				Oid			prevtypeid,
+							newtypeid;
+				int32		prevtypmod,
+							newtypmod;
+				Oid			prevcollid,
+							newcollid;
 
 				/*
 				 * Yes, try to merge the two column definitions.
@@ -2722,68 +2739,61 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				if (defTypeId != attribute->atttypid ||
-					deftypmod != attribute->atttypmod)
+				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(attribute->atttypid,
-																attribute->atttypmod))));
+									   format_type_with_typemod(prevtypeid, prevtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
-				if (defCollId != attribute->attcollation)
+				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (prevcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("inherited column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defCollId),
-									   get_collation_name(attribute->attcollation))));
+									   get_collation_name(prevcollid),
+									   get_collation_name(newcollid))));
 
 				/*
 				 * Copy/check storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = attribute->attstorage;
-				else if (def->storage != attribute->attstorage)
+				if (prevdef->storage == 0)
+					prevdef->storage = newdef->storage;
+				else if (prevdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
-									   storage_name(attribute->attstorage))));
+									   storage_name(prevdef->storage),
+									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy/check compression parameter
 				 */
-				if (CompressionMethodIsValid(attribute->attcompression))
-				{
-					const char *compression =
-						GetCompressionMethodName(attribute->attcompression);
-
-					if (def->compression == NULL)
-						def->compression = pstrdup(compression);
-					else if (strcmp(def->compression, compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
-				}
+				if (prevdef->compression == NULL)
+					prevdef->compression = newdef->compression;
+				else if (strcmp(prevdef->compression, newdef->compression) != 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has a compression method conflict",
+									attributeName),
+							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
 
 				/*
 				 * In regular inheritance, columns in the parent's primary key
@@ -2817,12 +2827,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
+					newdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
 				 */
-				if (def->generated != attribute->attgenerated)
+				if (prevdef->generated != newdef->generated)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a generation conflict",
@@ -2832,34 +2842,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * Default and other constraints are handled below
 				 */
 
-				def->inhcount++;
-				if (def->inhcount < 0)
+				prevdef->inhcount++;
+				if (prevdef->inhcount < 0)
 					ereport(ERROR,
 							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 							errmsg("too many inheritance parents"));
 
 				newattmap->attnums[parent_attno - 1] = exist_attno;
+
+				/* remember for default processing below */
+				savedef = prevdef;
 			}
 			else
 			{
 				/*
 				 * No, create a new inherited column
 				 */
-				def = makeColumnDef(attributeName, attribute->atttypid,
-									attribute->atttypmod, attribute->attcollation);
-				def->inhcount = 1;
-				def->is_local = false;
+				newdef->inhcount = 1;
+				newdef->is_local = false;
 				/* mark attnotnull if parent has it and it's not NO INHERIT */
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
-				def->storage = attribute->attstorage;
-				def->generated = attribute->attgenerated;
-				if (CompressionMethodIsValid(attribute->attcompression))
-					def->compression =
-						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inh_columns = lappend(inh_columns, def);
+					newdef->is_not_null = true;
+				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2888,6 +2894,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 					nnconstraints = lappend(nnconstraints, nn);
 				}
+
+				/* remember for default processing below */
+				savedef = newdef;
 			}
 
 			/*
@@ -2909,7 +2918,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, def);
+				cols_with_defaults = lappend(cols_with_defaults, savedef);
 			}
 		}
 
@@ -3047,17 +3056,17 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			newcol_attno++;
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Does it match some inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				ColumnDef  *def;
-				Oid			defTypeId,
-							newTypeId;
-				int32		deftypmod,
+				ColumnDef  *inhdef;
+				Oid			inhtypeid,
+							newtypeid;
+				int32		inhtypmod,
 							newtypmod;
-				Oid			defcollid,
+				Oid			inhcollid,
 							newcollid;
 
 				/*
@@ -3077,77 +3086,75 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
-				if (defTypeId != newTypeId || deftypmod != newtypmod)
+				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(newTypeId,
-																newtypmod))));
+									   format_type_with_typemod(inhtypeid, inhtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
-				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
-				if (defcollid != newcollid)
+				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (inhcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defcollid),
+									   get_collation_name(inhcollid),
 									   get_collation_name(newcollid))));
 
 				/*
 				 * Identity is never inherited.  The new column can have an
 				 * identity definition, so we always just take that one.
 				 */
-				def->identity = newdef->identity;
+				inhdef->identity = newdef->identity;
 
 				/*
 				 * Copy storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = newdef->storage;
-				else if (newdef->storage != 0 && def->storage != newdef->storage)
+				if (inhdef->storage == 0)
+					inhdef->storage = newdef->storage;
+				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
+									   storage_name(inhdef->storage),
 									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy compression parameter
 				 */
-				if (def->compression == NULL)
-					def->compression = newdef->compression;
+				if (inhdef->compression == NULL)
+					inhdef->compression = newdef->compression;
 				else if (newdef->compression != NULL)
 				{
-					if (strcmp(def->compression, newdef->compression) != 0)
+					if (strcmp(inhdef->compression, newdef->compression) != 0)
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
 				}
 
 				/*
 				 * Merge of not-null constraints = OR 'em together
 				 */
-				def->is_not_null |= newdef->is_not_null;
+				inhdef->is_not_null |= newdef->is_not_null;
 
 				/*
 				 * Check for conflicts related to generated columns.
@@ -3164,18 +3171,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * it results in being able to override the generation
 				 * expression via UPDATEs through the parent.)
 				 */
-				if (def->generated)
+				if (inhdef->generated)
 				{
 					if (newdef->raw_default && !newdef->generated)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										def->colname)));
+										inhdef->colname)));
 					if (newdef->identity)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										def->colname)));
+										inhdef->colname)));
 				}
 				else
 				{
@@ -3183,7 +3190,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("child column \"%s\" specifies generation expression",
-										def->colname),
+										inhdef->colname),
 								 errhint("A child table column cannot be generated unless its parent column is.")));
 				}
 
@@ -3192,12 +3199,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 */
 				if (newdef->raw_default != NULL)
 				{
-					def->raw_default = newdef->raw_default;
-					def->cooked_default = newdef->cooked_default;
+					inhdef->raw_default = newdef->raw_default;
+					inhdef->cooked_default = newdef->cooked_default;
 				}
 
 				/* Mark the column as locally defined */
-				def->is_local = true;
+				inhdef->is_local = true;
 			}
 			else
 			{
-- 
2.41.0

From 4d01d244305c63a5a602558267d0021910e200b6 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v2 01/10] Clean up MergeAttributesIntoExisting()

Make variable naming clearer and more consistent.  Move some variables
to smaller scope.  Remove some unnecessary intermediate variables.
Try to save some vertical space.

Apply analogous changes to nearby MergeConstraintsIntoExisting() and
RemoveInheritance() for consistency.
---
 src/backend/commands/tablecmds.c | 123 ++++++++++++-------------------
 1 file changed, 48 insertions(+), 75 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d097da3c78..e7846178b3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -15691,92 +15691,76 @@ static void
 MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 {
 	Relation	attrrel;
-	AttrNumber	parent_attno;
-	int			parent_natts;
-	TupleDesc	tupleDesc;
-	HeapTuple	tuple;
-	bool		child_is_partition = false;
+	TupleDesc	parent_desc;
 
 	attrrel = table_open(AttributeRelationId, RowExclusiveLock);
+	parent_desc = RelationGetDescr(parent_rel);
 
-	tupleDesc = RelationGetDescr(parent_rel);
-	parent_natts = tupleDesc->natts;
-
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
-
-	for (parent_attno = 1; parent_attno <= parent_natts; parent_attno++)
+	for (AttrNumber parent_attno = 1; parent_attno <= parent_desc->natts; parent_attno++)
 	{
-		Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
-													parent_attno - 1);
-		char	   *attributeName = NameStr(attribute->attname);
+		Form_pg_attribute parent_att = TupleDescAttr(parent_desc, parent_attno - 1);
+		char	   *parent_attname = NameStr(parent_att->attname);
+		HeapTuple	tuple;
 
 		/* Ignore dropped columns in the parent. */
-		if (attribute->attisdropped)
+		if (parent_att->attisdropped)
 			continue;
 
 		/* Find same column in child (matching on column name). */
-		tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel),
-										  attributeName);
+		tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel), parent_attname);
 		if (HeapTupleIsValid(tuple))
 		{
-			/* Check they are same type, typmod, and collation */
-			Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);
+			Form_pg_attribute child_att = (Form_pg_attribute) GETSTRUCT(tuple);
 
-			if (attribute->atttypid != childatt->atttypid ||
-				attribute->atttypmod != childatt->atttypmod)
+			if (parent_att->atttypid != child_att->atttypid ||
+				parent_att->atttypmod != child_att->atttypmod)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different type for column \"%s\"",
-								RelationGetRelationName(child_rel),
-								attributeName)));
+								RelationGetRelationName(child_rel), parent_attname)));
 
-			if (attribute->attcollation != childatt->attcollation)
+			if (parent_att->attcollation != child_att->attcollation)
 				ereport(ERROR,
 						(errcode(ERRCODE_COLLATION_MISMATCH),
 						 errmsg("child table \"%s\" has different collation for column \"%s\"",
-								RelationGetRelationName(child_rel),
-								attributeName)));
+								RelationGetRelationName(child_rel), parent_attname)));
 
 			/*
 			 * Check child doesn't discard NOT NULL property.  (Other
 			 * constraints are checked elsewhere.)  However, if the constraint
 			 * is NO INHERIT in the parent, this is allowed.
 			 */
-			if (attribute->attnotnull && !childatt->attnotnull)
+			if (parent_att->attnotnull && !child_att->attnotnull)
 			{
 				HeapTuple	contup;
 
 				contup = findNotNullConstraintAttnum(RelationGetRelid(parent_rel),
-													 attribute->attnum);
+													 parent_att->attnum);
 				if (!((Form_pg_constraint) GETSTRUCT(contup))->connoinherit)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" in child table must be marked NOT NULL",
-									attributeName)));
+									parent_attname)));
 			}
 
 			/*
 			 * Child column must be generated if and only if parent column is.
 			 */
-			if (attribute->attgenerated && !childatt->attgenerated)
+			if (parent_att->attgenerated && !child_att->attgenerated)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("column \"%s\" in child table must be a generated column",
-								attributeName)));
-			if (childatt->attgenerated && !attribute->attgenerated)
+						 errmsg("column \"%s\" in child table must be a generated column", parent_attname)));
+			if (child_att->attgenerated && !parent_att->attgenerated)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("column \"%s\" in child table must not be a generated column",
-								attributeName)));
+						 errmsg("column \"%s\" in child table must not be a generated column", parent_attname)));
 
 			/*
 			 * OK, bump the child column's inheritance count.  (If we fail
 			 * later on, this change will just roll back.)
 			 */
-			childatt->attinhcount++;
-			if (childatt->attinhcount < 0)
+			child_att->attinhcount++;
+			if (child_att->attinhcount < 0)
 				ereport(ERROR,
 						errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 						errmsg("too many inheritance parents"));
@@ -15786,10 +15770,10 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 			 * is same in all partitions. (Note: there are only inherited
 			 * attributes in partitions)
 			 */
-			if (child_is_partition)
+			if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 			{
-				Assert(childatt->attinhcount == 1);
-				childatt->attislocal = false;
+				Assert(child_att->attinhcount == 1);
+				child_att->attislocal = false;
 			}
 
 			CatalogTupleUpdate(attrrel, &tuple->t_self, tuple);
@@ -15799,8 +15783,7 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 		{
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
-					 errmsg("child table is missing column \"%s\"",
-							attributeName)));
+					 errmsg("child table is missing column \"%s\"", parent_attname)));
 		}
 	}
 
@@ -15827,27 +15810,20 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 static void
 MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 {
-	Relation	catalog_relation;
-	TupleDesc	tuple_desc;
+	Relation	constraintrel;
 	SysScanDesc parent_scan;
 	ScanKeyData parent_key;
 	HeapTuple	parent_tuple;
 	Oid			parent_relid = RelationGetRelid(parent_rel);
-	bool		child_is_partition = false;
-
-	catalog_relation = table_open(ConstraintRelationId, RowExclusiveLock);
-	tuple_desc = RelationGetDescr(catalog_relation);
 
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
+	constraintrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
 	/* Outer loop scans through the parent's constraint definitions */
 	ScanKeyInit(&parent_key,
 				Anum_pg_constraint_conrelid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(parent_relid));
-	parent_scan = systable_beginscan(catalog_relation, ConstraintRelidTypidNameIndexId,
+	parent_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
 									 true, NULL, 1, &parent_key);
 
 	while (HeapTupleIsValid(parent_tuple = systable_getnext(parent_scan)))
@@ -15871,7 +15847,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 					Anum_pg_constraint_conrelid,
 					BTEqualStrategyNumber, F_OIDEQ,
 					ObjectIdGetDatum(RelationGetRelid(child_rel)));
-		child_scan = systable_beginscan(catalog_relation, ConstraintRelidTypidNameIndexId,
+		child_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
 										true, NULL, 1, &child_key);
 
 		while (HeapTupleIsValid(child_tuple = systable_getnext(child_scan)))
@@ -15886,10 +15862,12 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			 * CHECK constraint are matched by name, NOT NULL ones by
 			 * attribute number
 			 */
-			if (child_con->contype == CONSTRAINT_CHECK &&
-				strcmp(NameStr(parent_con->conname),
-					   NameStr(child_con->conname)) != 0)
-				continue;
+			if (child_con->contype == CONSTRAINT_CHECK)
+			{
+				if (strcmp(NameStr(parent_con->conname),
+						   NameStr(child_con->conname)) != 0)
+					continue;
+			}
 			else if (child_con->contype == CONSTRAINT_NOTNULL)
 			{
 				AttrNumber	parent_attno = extractNotNullColumn(parent_tuple);
@@ -15902,12 +15880,11 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			}
 
 			if (child_con->contype == CONSTRAINT_CHECK &&
-				!constraints_equivalent(parent_tuple, child_tuple, tuple_desc))
+				!constraints_equivalent(parent_tuple, child_tuple, RelationGetDescr(constraintrel)))
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different definition for check constraint \"%s\"",
-								RelationGetRelationName(child_rel),
-								NameStr(parent_con->conname))));
+								RelationGetRelationName(child_rel), NameStr(parent_con->conname))));
 
 			/*
 			 * If the CHECK child constraint is "no inherit" then cannot
@@ -15925,8 +15902,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 						 errmsg("constraint \"%s\" conflicts with non-inherited constraint on child table \"%s\"",
-								NameStr(child_con->conname),
-								RelationGetRelationName(child_rel))));
+								NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
 			/*
 			 * If the child constraint is "not valid" then cannot merge with a
@@ -15936,8 +15912,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 						 errmsg("constraint \"%s\" conflicts with NOT VALID constraint on child table \"%s\"",
-								NameStr(child_con->conname),
-								RelationGetRelationName(child_rel))));
+								NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
 			/*
 			 * OK, bump the child constraint's inheritance count.  (If we fail
@@ -15959,13 +15934,13 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			 * inherited only once since it cannot have multiple parents and
 			 * it is never considered local.
 			 */
-			if (child_is_partition)
+			if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 			{
 				Assert(child_con->coninhcount == 1);
 				child_con->conislocal = false;
 			}
 
-			CatalogTupleUpdate(catalog_relation, &child_copy->t_self, child_copy);
+			CatalogTupleUpdate(constraintrel, &child_copy->t_self, child_copy);
 			heap_freetuple(child_copy);
 
 			found = true;
@@ -15982,7 +15957,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 	}
 
 	systable_endscan(parent_scan);
-	table_close(catalog_relation, RowExclusiveLock);
+	table_close(constraintrel, RowExclusiveLock);
 }
 
 /*
@@ -16138,11 +16113,9 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 	List	   *connames;
 	List	   *nncolumns;
 	bool		found;
-	bool		child_is_partition = false;
+	bool		is_partitioning;
 
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
+	is_partitioning = (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
 	found = DeleteInheritsTuple(RelationGetRelid(child_rel),
 								RelationGetRelid(parent_rel),
@@ -16150,7 +16123,7 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 								RelationGetRelationName(child_rel));
 	if (!found)
 	{
-		if (child_is_partition)
+		if (is_partitioning)
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_TABLE),
 					 errmsg("relation \"%s\" is not a partition of relation \"%s\"",
@@ -16304,7 +16277,7 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 	drop_parent_dependency(RelationGetRelid(child_rel),
 						   RelationRelationId,
 						   RelationGetRelid(parent_rel),
-						   child_dependency_type(child_is_partition));
+						   child_dependency_type(is_partitioning));
 
 	/*
 	 * Post alter hook of this inherits. Since object_access_hook doesn't take

base-commit: 6844d3275ac6b3c35d824f49362d3fe59b30f26b
-- 
2.41.0

From cbf88a4e5ee9e5d0190a69c5ac81737501185254 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v2 02/10] Clean up MergeCheckConstraint()

If the constraint is not already in the list, add it ourselves,
instead of making the caller do it.  This makes the interface more
consistent with other "merge" functions in this file.
---
 src/backend/commands/tablecmds.c | 47 ++++++++++++++------------------
 1 file changed, 21 insertions(+), 26 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index e7846178b3..c37161aefa 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -353,7 +353,7 @@ static void RangeVarCallbackForTruncate(const RangeVar *relation,
 static List *MergeAttributes(List *schema, List *supers, char relpersistence,
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
-static bool MergeCheckConstraint(List *constraints, char *name, Node *expr);
+static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
 static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel);
 static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
 static void StoreCatalogInheritance(Oid relationId, List *supers,
@@ -2914,24 +2914,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   name,
 									   RelationGetRelationName(relation))));
 
-				/* check for duplicate */
-				if (!MergeCheckConstraint(constraints, name, expr))
-				{
-					/* nope, this is a new one */
-					CookedConstraint *cooked;
-
-					cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
-					cooked->contype = CONSTR_CHECK;
-					cooked->conoid = InvalidOid;	/* until created */
-					cooked->name = pstrdup(name);
-					cooked->attnum = 0; /* not used for constraints */
-					cooked->expr = expr;
-					cooked->skip_validation = false;
-					cooked->is_local = false;
-					cooked->inhcount = 1;
-					cooked->is_no_inherit = false;
-					constraints = lappend(constraints, cooked);
-				}
+				constraints = MergeCheckConstraint(constraints, name, expr);
 			}
 		}
 
@@ -3278,13 +3261,16 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
  *
  * constraints is a list of CookedConstraint structs for previous constraints.
  *
- * Returns true if merged (constraint is a duplicate), or false if it's
- * got a so-far-unique name, or throws error if conflict.
+ * If the constraint is a duplicate, then the existing constraint's
+ * inheritance count is updated.  If the constraint doesn't match or conflict
+ * with an existing one, a new constraint is appended to the list.  If there
+ * is a conflict (same name but different expression), throw an error.
  */
-static bool
-MergeCheckConstraint(List *constraints, char *name, Node *expr)
+static List *
+MergeCheckConstraint(List *constraints, const char *name, Node *expr)
 {
 	ListCell   *lc;
+	CookedConstraint *newcon;
 
 	foreach(lc, constraints)
 	{
@@ -3298,13 +3284,13 @@ MergeCheckConstraint(List *constraints, char *name, Node *expr)
 
 		if (equal(expr, ccon->expr))
 		{
-			/* OK to merge */
+			/* OK to merge constraint with existing */
 			ccon->inhcount++;
 			if (ccon->inhcount < 0)
 				ereport(ERROR,
 						errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 						errmsg("too many inheritance parents"));
-			return true;
+			return constraints;
 		}
 
 		ereport(ERROR,
@@ -3313,7 +3299,16 @@ MergeCheckConstraint(List *constraints, char *name, Node *expr)
 						name)));
 	}
 
-	return false;
+	/*
+	 * Constraint couldn't be merged with an existing one and also didn't
+	 * conflict with an existing one, so add it as a new one to the list.
+	 */
+	newcon = palloc0_object(CookedConstraint);
+	newcon->contype = CONSTR_CHECK;
+	newcon->name = pstrdup(name);
+	newcon->expr = expr;
+	newcon->inhcount = 1;
+	return lappend(constraints, newcon);
 }
 
 
-- 
2.41.0

From 1820aff805349ab2a780829944c8e64b9352efb3 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v2 03/10] MergeAttributes() and related variable renaming

Mainly, rename "schema" to "columns" and related changes.  The
previous naming has long been confusing.
---
 src/backend/access/common/tupdesc.c |  10 +--
 src/backend/commands/tablecmds.c    | 109 +++++++++++++---------------
 src/include/access/tupdesc.h        |   4 +-
 3 files changed, 59 insertions(+), 64 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 7c5c390503..253d6c86f8 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -782,12 +782,12 @@ TupleDescInitEntryCollation(TupleDesc desc,
 /*
  * BuildDescForRelation
  *
- * Given a relation schema (list of ColumnDef nodes), build a TupleDesc.
+ * Given a list of ColumnDef nodes, build a TupleDesc.
  *
  * Note: tdtypeid will need to be filled in later on.
  */
 TupleDesc
-BuildDescForRelation(List *schema)
+BuildDescForRelation(const List *columns)
 {
 	int			natts;
 	AttrNumber	attnum;
@@ -803,13 +803,13 @@ BuildDescForRelation(List *schema)
 	/*
 	 * allocate a new tuple descriptor
 	 */
-	natts = list_length(schema);
+	natts = list_length(columns);
 	desc = CreateTemplateTupleDesc(natts);
 	has_not_null = false;
 
 	attnum = 0;
 
-	foreach(l, schema)
+	foreach(l, columns)
 	{
 		ColumnDef  *entry = lfirst(l);
 		AclResult	aclresult;
@@ -891,7 +891,7 @@ BuildDescForRelation(List *schema)
  * with functions returning RECORD.
  */
 TupleDesc
-BuildDescFromLists(List *names, List *types, List *typmods, List *collations)
+BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)
 {
 	int			natts;
 	AttrNumber	attnum;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index c37161aefa..fb6d1b90dc 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -350,7 +350,7 @@ static void truncate_check_perms(Oid relid, Form_pg_class reltuple);
 static void truncate_check_activity(Relation rel);
 static void RangeVarCallbackForTruncate(const RangeVar *relation,
 										Oid relId, Oid oldRelId, void *arg);
-static List *MergeAttributes(List *schema, List *supers, char relpersistence,
+static List *MergeAttributes(List *columns, const List *supers, char relpersistence,
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
 static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
@@ -361,7 +361,7 @@ static void StoreCatalogInheritance(Oid relationId, List *supers,
 static void StoreCatalogInheritance1(Oid relationId, Oid parentOid,
 									 int32 seqNumber, Relation inhRelation,
 									 bool child_is_partition);
-static int	findAttrByName(const char *attributeName, List *schema);
+static int	findAttrByName(const char *attributeName, const List *columns);
 static void AlterIndexNamespaces(Relation classRel, Relation rel,
 								 Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved);
 static void AlterSeqNamespaces(Relation classRel, Relation rel,
@@ -2308,7 +2308,7 @@ storage_name(char c)
  *		Returns new schema given initial schema and superclasses.
  *
  * Input arguments:
- * 'schema' is the column/attribute definition for the table. (It's a list
+ * 'columns' is the column/attribute definition for the table. (It's a list
  *		of ColumnDef's.) It is destructively changed.
  * 'supers' is a list of OIDs of parent relations, already locked by caller.
  * 'relpersistence' is the persistence type of the table.
@@ -2370,17 +2370,17 @@ storage_name(char c)
  *----------
  */
 static List *
-MergeAttributes(List *schema, List *supers, char relpersistence,
+MergeAttributes(List *columns, const List *supers, char relpersistence,
 				bool is_partition, List **supconstr, List **supnotnulls)
 {
-	List	   *inhSchema = NIL;
+	List	   *inh_columns = NIL;
 	List	   *constraints = NIL;
 	List	   *nnconstraints = NIL;
 	bool		have_bogus_defaults = false;
 	int			child_attno;
 	static Node bogus_marker = {0}; /* marks conflicting defaults */
-	List	   *saved_schema = NIL;
-	ListCell   *entry;
+	List	   *saved_columns = NIL;
+	ListCell   *lc;
 
 	/*
 	 * Check for and reject tables with too many columns. We perform this
@@ -2393,7 +2393,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 * Note that we also need to check that we do not exceed this figure after
 	 * including columns from inherited relations.
 	 */
-	if (list_length(schema) > MaxHeapAttributeNumber)
+	if (list_length(columns) > MaxHeapAttributeNumber)
 		ereport(ERROR,
 				(errcode(ERRCODE_TOO_MANY_COLUMNS),
 				 errmsg("tables can have at most %d columns",
@@ -2407,15 +2407,15 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 * sense to assume such conflicts are errors.
 	 *
 	 * We don't use foreach() here because we have two nested loops over the
-	 * schema list, with possible element deletions in the inner one.  If we
+	 * columns list, with possible element deletions in the inner one.  If we
 	 * used foreach_delete_current() it could only fix up the state of one of
 	 * the loops, so it seems cleaner to use looping over list indexes for
 	 * both loops.  Note that any deletion will happen beyond where the outer
 	 * loop is, so its index never needs adjustment.
 	 */
-	for (int coldefpos = 0; coldefpos < list_length(schema); coldefpos++)
+	for (int coldefpos = 0; coldefpos < list_length(columns); coldefpos++)
 	{
-		ColumnDef  *coldef = list_nth_node(ColumnDef, schema, coldefpos);
+		ColumnDef  *coldef = list_nth_node(ColumnDef, columns, coldefpos);
 
 		if (!is_partition && coldef->typeName == NULL)
 		{
@@ -2432,9 +2432,9 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		}
 
 		/* restpos scans all entries beyond coldef; incr is in loop body */
-		for (int restpos = coldefpos + 1; restpos < list_length(schema);)
+		for (int restpos = coldefpos + 1; restpos < list_length(columns);)
 		{
-			ColumnDef  *restdef = list_nth_node(ColumnDef, schema, restpos);
+			ColumnDef  *restdef = list_nth_node(ColumnDef, columns, restpos);
 
 			if (strcmp(coldef->colname, restdef->colname) == 0)
 			{
@@ -2448,7 +2448,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 					coldef->cooked_default = restdef->cooked_default;
 					coldef->constraints = restdef->constraints;
 					coldef->is_from_type = false;
-					schema = list_delete_nth_cell(schema, restpos);
+					columns = list_delete_nth_cell(columns, restpos);
 				}
 				else
 					ereport(ERROR,
@@ -2468,18 +2468,18 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (is_partition)
 	{
-		saved_schema = schema;
-		schema = NIL;
+		saved_columns = columns;
+		columns = NIL;
 	}
 
 	/*
 	 * Scan the parents left-to-right, and merge their attributes to form a
-	 * list of inherited attributes (inhSchema).
+	 * list of inherited columns (inh_columns).
 	 */
 	child_attno = 0;
-	foreach(entry, supers)
+	foreach(lc, supers)
 	{
-		Oid			parent = lfirst_oid(entry);
+		Oid			parent = lfirst_oid(lc);
 		Relation	relation;
 		TupleDesc	tupleDesc;
 		TupleConstr *constr;
@@ -2487,7 +2487,6 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		List	   *inherited_defaults;
 		List	   *cols_with_defaults;
 		List	   *nnconstrs;
-		AttrNumber	parent_attno;
 		ListCell   *lc1;
 		ListCell   *lc2;
 		Bitmapset  *pkattrs;
@@ -2508,8 +2507,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		 * We do not allow partitioned tables and partitions to participate in
 		 * regular inheritance.
 		 */
-		if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
-			!is_partition)
+		if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE && !is_partition)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 					 errmsg("cannot inherit from partitioned table \"%s\"",
@@ -2594,7 +2592,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			nncols = bms_add_member(nncols,
 									((CookedConstraint *) lfirst(lc1))->attnum);
 
-		for (parent_attno = 1; parent_attno <= tupleDesc->natts;
+		for (AttrNumber parent_attno = 1; parent_attno <= tupleDesc->natts;
 			 parent_attno++)
 		{
 			Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
@@ -2612,7 +2610,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			/*
 			 * Does it conflict with some previously inherited column?
 			 */
-			exist_attno = findAttrByName(attributeName, inhSchema);
+			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
 				Oid			defTypeId;
@@ -2625,7 +2623,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
+				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
@@ -2762,7 +2760,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				if (CompressionMethodIsValid(attribute->attcompression))
 					def->compression =
 						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inhSchema = lappend(inhSchema, def);
+				inh_columns = lappend(inh_columns, def);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2863,7 +2861,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			 * If we already had a default from some prior parent, check to
 			 * see if they are the same.  If so, no problem; if not, mark the
 			 * column as having a bogus default.  Below, we will complain if
-			 * the bogus default isn't overridden by the child schema.
+			 * the bogus default isn't overridden by the child columns.
 			 */
 			Assert(def->raw_default == NULL);
 			if (def->cooked_default == NULL)
@@ -2883,9 +2881,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		if (constr && constr->num_check > 0)
 		{
 			ConstrCheck *check = constr->check;
-			int			i;
 
-			for (i = 0; i < constr->num_check; i++)
+			for (int i = 0; i < constr->num_check; i++)
 			{
 				char	   *name = check[i].ccname;
 				Node	   *expr;
@@ -2946,27 +2943,27 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	}
 
 	/*
-	 * If we had no inherited attributes, the result schema is just the
+	 * If we had no inherited attributes, the result columns are just the
 	 * explicitly declared columns.  Otherwise, we need to merge the declared
-	 * columns into the inherited schema list.  Although, we never have any
+	 * columns into the inherited column list.  Although, we never have any
 	 * explicitly declared columns if the table is a partition.
 	 */
-	if (inhSchema != NIL)
+	if (inh_columns != NIL)
 	{
-		int			schema_attno = 0;
+		int			newcol_attno = 0;
 
-		foreach(entry, schema)
+		foreach(lc, columns)
 		{
-			ColumnDef  *newdef = lfirst(entry);
+			ColumnDef  *newdef = lfirst(lc);
 			char	   *attributeName = newdef->colname;
 			int			exist_attno;
 
-			schema_attno++;
+			newcol_attno++;
 
 			/*
 			 * Does it conflict with some previously inherited column?
 			 */
-			exist_attno = findAttrByName(attributeName, inhSchema);
+			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
 				ColumnDef  *def;
@@ -2986,7 +2983,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				/*
 				 * Yes, try to merge the two column definitions.
 				 */
-				if (exist_attno == schema_attno)
+				if (exist_attno == newcol_attno)
 					ereport(NOTICE,
 							(errmsg("merging column \"%s\" with inherited definition",
 									attributeName)));
@@ -2994,7 +2991,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
+				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
@@ -3119,19 +3116,19 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			else
 			{
 				/*
-				 * No, attach new column to result schema
+				 * No, attach new column to result columns
 				 */
-				inhSchema = lappend(inhSchema, newdef);
+				inh_columns = lappend(inh_columns, newdef);
 			}
 		}
 
-		schema = inhSchema;
+		columns = inh_columns;
 
 		/*
 		 * Check that we haven't exceeded the legal # of columns after merging
 		 * in inherited columns.
 		 */
-		if (list_length(schema) > MaxHeapAttributeNumber)
+		if (list_length(columns) > MaxHeapAttributeNumber)
 			ereport(ERROR,
 					(errcode(ERRCODE_TOO_MANY_COLUMNS),
 					 errmsg("tables can have at most %d columns",
@@ -3145,13 +3142,13 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (is_partition)
 	{
-		foreach(entry, saved_schema)
+		foreach(lc, saved_columns)
 		{
-			ColumnDef  *restdef = lfirst(entry);
+			ColumnDef  *restdef = lfirst(lc);
 			bool		found = false;
 			ListCell   *l;
 
-			foreach(l, schema)
+			foreach(l, columns)
 			{
 				ColumnDef  *coldef = lfirst(l);
 
@@ -3223,9 +3220,9 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (have_bogus_defaults)
 	{
-		foreach(entry, schema)
+		foreach(lc, columns)
 		{
-			ColumnDef  *def = lfirst(entry);
+			ColumnDef  *def = lfirst(lc);
 
 			if (def->cooked_default == &bogus_marker)
 			{
@@ -3248,7 +3245,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	*supconstr = constraints;
 	*supnotnulls = nnconstraints;
 
-	return schema;
+	return columns;
 }
 
 
@@ -3402,22 +3399,20 @@ StoreCatalogInheritance1(Oid relationId, Oid parentOid,
 }
 
 /*
- * Look for an existing schema entry with the given name.
+ * Look for an existing column entry with the given name.
  *
- * Returns the index (starting with 1) if attribute already exists in schema,
+ * Returns the index (starting with 1) if attribute already exists in columns,
  * 0 if it doesn't.
  */
 static int
-findAttrByName(const char *attributeName, List *schema)
+findAttrByName(const char *attributeName, const List *columns)
 {
-	ListCell   *s;
+	ListCell   *lc;
 	int			i = 1;
 
-	foreach(s, schema)
+	foreach(lc, columns)
 	{
-		ColumnDef  *def = lfirst(s);
-
-		if (strcmp(attributeName, def->colname) == 0)
+		if (strcmp(attributeName, lfirst_node(ColumnDef, lc)->colname) == 0)
 			return i;
 
 		i++;
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index b4286cf922..f6cc28a661 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -147,8 +147,8 @@ extern void TupleDescInitEntryCollation(TupleDesc desc,
 										AttrNumber attributeNumber,
 										Oid collationid);
 
-extern TupleDesc BuildDescForRelation(List *schema);
+extern TupleDesc BuildDescForRelation(const List *columns);
 
-extern TupleDesc BuildDescFromLists(List *names, List *types, List *typmods, List *collations);
+extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
 #endif							/* TUPDESC_H */
-- 
2.41.0

From 471fda80c41fae835ecbe63ae8505526a37487a9 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 04/10] Add TupleDescGetDefault()

This unifies some repetitive code.

Note: I didn't push the "not found" error message into the new
function, even though all existing callers would be able to make use
of it.  Using the existing error handling as-is would probably require
exposing the Relation type via tupdesc.h, which doesn't seem
desirable.
---
 src/backend/access/common/tupdesc.c  | 25 +++++++++++++++++++++++++
 src/backend/commands/tablecmds.c     | 17 ++---------------
 src/backend/parser/parse_utilcmd.c   | 13 ++-----------
 src/backend/rewrite/rewriteHandler.c | 16 +---------------
 src/include/access/tupdesc.h         |  2 ++
 5 files changed, 32 insertions(+), 41 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 253d6c86f8..ce2c7bce85 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -927,3 +927,28 @@ BuildDescFromLists(const List *names, const List *types, const List *typmods, co
 
 	return desc;
 }
+
+/*
+ * Get default expression (or NULL if none) for the given attribute number.
+ */
+Node *
+TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum)
+{
+	Node	   *result = NULL;
+
+	if (tupdesc->constr)
+	{
+		AttrDefault *attrdef = tupdesc->constr->defval;
+
+		for (int i = 0; i < tupdesc->constr->num_defval; i++)
+		{
+			if (attrdef[i].adnum == attnum)
+			{
+				result = stringToNode(attrdef[i].adbin);
+				break;
+			}
+		}
+	}
+
+	return result;
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index fb6d1b90dc..0a7101dadc 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2796,22 +2796,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			 */
 			if (attribute->atthasdef)
 			{
-				Node	   *this_default = NULL;
+				Node	   *this_default;
 
-				/* Find default in constraint structure */
-				if (constr != NULL)
-				{
-					AttrDefault *attrdef = constr->defval;
-
-					for (int i = 0; i < constr->num_defval; i++)
-					{
-						if (attrdef[i].adnum == parent_attno)
-						{
-							this_default = stringToNode(attrdef[i].adbin);
-							break;
-						}
-					}
-				}
+				this_default = TupleDescGetDefault(tupleDesc, parent_attno);
 				if (this_default == NULL)
 					elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 						 parent_attno, RelationGetRelationName(relation));
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 55c315f0e2..cf0d432ab1 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1358,20 +1358,11 @@ expandTableLikeClause(RangeVar *heapRel, TableLikeClause *table_like_clause)
 				 (table_like_clause->options & CREATE_TABLE_LIKE_GENERATED) :
 				 (table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS)))
 			{
-				Node	   *this_default = NULL;
-				AttrDefault *attrdef = constr->defval;
+				Node	   *this_default;
 				AlterTableCmd *atsubcmd;
 				bool		found_whole_row;
 
-				/* Find default in constraint structure */
-				for (int i = 0; i < constr->num_defval; i++)
-				{
-					if (attrdef[i].adnum == parent_attno)
-					{
-						this_default = stringToNode(attrdef[i].adbin);
-						break;
-					}
-				}
+				this_default = TupleDescGetDefault(tupleDesc, parent_attno);
 				if (this_default == NULL)
 					elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 						 parent_attno, RelationGetRelationName(relation));
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index b486ab559a..41a362310a 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -1246,21 +1246,7 @@ build_column_default(Relation rel, int attrno)
 	 */
 	if (att_tup->atthasdef)
 	{
-		if (rd_att->constr && rd_att->constr->num_defval > 0)
-		{
-			AttrDefault *defval = rd_att->constr->defval;
-			int			ndef = rd_att->constr->num_defval;
-
-			while (--ndef >= 0)
-			{
-				if (attrno == defval[ndef].adnum)
-				{
-					/* Found it, convert string representation to node tree. */
-					expr = stringToNode(defval[ndef].adbin);
-					break;
-				}
-			}
-		}
+		expr = TupleDescGetDefault(rd_att, attrno);
 		if (expr == NULL)
 			elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 				 attrno, RelationGetRelationName(rel));
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index f6cc28a661..ffd2874ee3 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -151,4 +151,6 @@ extern TupleDesc BuildDescForRelation(const List *columns);
 
 extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
+extern Node *TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum);
+
 #endif							/* TUPDESC_H */
-- 
2.41.0

From 2c1c802be10ac574abf33d6293c8db7309d6b157 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 05/10] Improve some catalog documentation

Point out that typstorage and attstorage are never '\0', even for
fixed-length types.  This is different from attcompression.  For this
reason, some of the handling of these columns in tablecmds.c etc. is
different.  (catalogs.sgml already contained this information in an
indirect way.)
---
 src/include/catalog/pg_attribute.h | 10 +++++-----
 src/include/catalog/pg_type.h      |  3 +++
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index f00df488ce..9b7442493a 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -108,11 +108,11 @@ CATALOG(pg_attribute,1249,AttributeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(75,
 	 */
 	char		attalign;
 
-	/*----------
-	 * attstorage tells for VARLENA attributes, what the heap access
-	 * methods can do to it if a given tuple doesn't fit into a page.
-	 * Possible values are as for pg_type.typstorage (see TYPSTORAGE macros).
-	 *----------
+	/*
+	 * attstorage tells for VARLENA attributes, what the heap access methods
+	 * can do to it if a given tuple doesn't fit into a page.  Possible values
+	 * are as for pg_type.typstorage (see TYPSTORAGE macros).  This is never
+	 * '\0', even for fixed-length types.
 	 */
 	char		attstorage;
 
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index 519e570c8c..e0a86354ff 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -187,6 +187,9 @@ CATALOG(pg_type,1247,TypeRelationId) BKI_BOOTSTRAP BKI_ROWTYPE_OID(71,TypeRelati
 	 *
 	 * Note that 'm' fields can also be moved out to secondary storage,
 	 * but only as a last resort ('e' and 'x' fields are moved first).
+	 *
+	 * For types that are not variable-length (that is, typlen != -1), this
+	 * must be set to 'p'.
 	 * ----------------
 	 */
 	char		typstorage BKI_DEFAULT(p) BKI_ARRAY_DEFAULT(x);
-- 
2.41.0

From 622b51c51f5f0d52abea5fc08931811ca6b994df Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 06/10] Push attidentity and attgenerated handling into
 BuildDescForRelation()

Previously, this was handled by the callers separately, but it can be
trivially moved into BuildDescForRelation() so that it is handled in a
central place.
---
 src/backend/access/common/tupdesc.c | 2 ++
 src/backend/commands/tablecmds.c    | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index ce2c7bce85..c2e7b14c31 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -856,6 +856,8 @@ BuildDescForRelation(const List *columns)
 		has_not_null |= entry->is_not_null;
 		att->attislocal = entry->is_local;
 		att->attinhcount = entry->inhcount;
+		att->attidentity = entry->identity;
+		att->attgenerated = entry->generated;
 	}
 
 	if (has_not_null)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0a7101dadc..c3a8cd58dd 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -942,8 +942,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			attr->atthasdef = true;
 		}
 
-		attr->attidentity = colDef->identity;
-		attr->attgenerated = colDef->generated;
 		attr->attcompression = GetAttributeCompression(attr->atttypid, colDef->compression);
 		if (colDef->storage_name)
 			attr->attstorage = GetAttributeStorage(attr->atttypid, colDef->storage_name);
-- 
2.41.0

From 762ee0c108b267ae8a20fa7c8e2ece0f40e99b5f Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 07/10] Move BuildDescForRelation() from tupdesc.c to
 tablecmds.c

BuildDescForRelation() main job is to convert ColumnDef lists to
pg_attribute/tuple descriptor arrays, which is really mostly an
internal subroutine of DefineRelation() and some related functions,
which is more the remit of tablecmds.c and doesn't have much to do
with the basic tuple descriptor interfaces in tupdesc.c.  This is also
supported by observing the header includes we can remove in tupdesc.c.
By moving it over, we can also (in the future) make
BuildDescForRelation() use more internals of tablecmds.c that are not
sensible to be exposed in tupdesc.c.
---
 src/backend/access/common/tupdesc.c | 109 +---------------------------
 src/backend/commands/tablecmds.c    | 102 ++++++++++++++++++++++++++
 src/include/access/tupdesc.h        |   2 -
 src/include/commands/tablecmds.h    |   2 +
 4 files changed, 105 insertions(+), 110 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index c2e7b14c31..d119cfafb5 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -25,9 +25,6 @@
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/hashfn.h"
-#include "miscadmin.h"
-#include "parser/parse_type.h"
-#include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
 #include "utils/resowner_private.h"
@@ -778,109 +775,6 @@ TupleDescInitEntryCollation(TupleDesc desc,
 	TupleDescAttr(desc, attributeNumber - 1)->attcollation = collationid;
 }
 
-
-/*
- * BuildDescForRelation
- *
- * Given a list of ColumnDef nodes, build a TupleDesc.
- *
- * Note: tdtypeid will need to be filled in later on.
- */
-TupleDesc
-BuildDescForRelation(const List *columns)
-{
-	int			natts;
-	AttrNumber	attnum;
-	ListCell   *l;
-	TupleDesc	desc;
-	bool		has_not_null;
-	char	   *attname;
-	Oid			atttypid;
-	int32		atttypmod;
-	Oid			attcollation;
-	int			attdim;
-
-	/*
-	 * allocate a new tuple descriptor
-	 */
-	natts = list_length(columns);
-	desc = CreateTemplateTupleDesc(natts);
-	has_not_null = false;
-
-	attnum = 0;
-
-	foreach(l, columns)
-	{
-		ColumnDef  *entry = lfirst(l);
-		AclResult	aclresult;
-		Form_pg_attribute att;
-
-		/*
-		 * for each entry in the list, get the name and type information from
-		 * the list and have TupleDescInitEntry fill in the attribute
-		 * information we need.
-		 */
-		attnum++;
-
-		attname = entry->colname;
-		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
-
-		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
-		if (aclresult != ACLCHECK_OK)
-			aclcheck_error_type(aclresult, atttypid);
-
-		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
-		attdim = list_length(entry->typeName->arrayBounds);
-		if (attdim > PG_INT16_MAX)
-			ereport(ERROR,
-					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-					errmsg("too many array dimensions"));
-
-		if (entry->typeName->setof)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("column \"%s\" cannot be declared SETOF",
-							attname)));
-
-		TupleDescInitEntry(desc, attnum, attname,
-						   atttypid, atttypmod, attdim);
-		att = TupleDescAttr(desc, attnum - 1);
-
-		/* Override TupleDescInitEntry's settings as requested */
-		TupleDescInitEntryCollation(desc, attnum, attcollation);
-		if (entry->storage)
-			att->attstorage = entry->storage;
-
-		/* Fill in additional stuff not handled by TupleDescInitEntry */
-		att->attnotnull = entry->is_not_null;
-		has_not_null |= entry->is_not_null;
-		att->attislocal = entry->is_local;
-		att->attinhcount = entry->inhcount;
-		att->attidentity = entry->identity;
-		att->attgenerated = entry->generated;
-	}
-
-	if (has_not_null)
-	{
-		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
-
-		constr->has_not_null = true;
-		constr->has_generated_stored = false;
-		constr->defval = NULL;
-		constr->missing = NULL;
-		constr->num_defval = 0;
-		constr->check = NULL;
-		constr->num_check = 0;
-		desc->constr = constr;
-	}
-	else
-	{
-		desc->constr = NULL;
-	}
-
-	return desc;
-}
-
 /*
  * BuildDescFromLists
  *
@@ -889,8 +783,7 @@ BuildDescForRelation(const List *columns)
  *
  * No constraints are generated.
  *
- * This is essentially a cut-down version of BuildDescForRelation for use
- * with functions returning RECORD.
+ * This is for use with functions returning RECORD.
  */
 TupleDesc
 BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index c3a8cd58dd..0577e29230 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1278,6 +1278,108 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	return address;
 }
 
+/*
+ * BuildDescForRelation
+ *
+ * Given a list of ColumnDef nodes, build a TupleDesc.
+ *
+ * Note: tdtypeid will need to be filled in later on.
+ */
+TupleDesc
+BuildDescForRelation(const List *columns)
+{
+	int			natts;
+	AttrNumber	attnum;
+	ListCell   *l;
+	TupleDesc	desc;
+	bool		has_not_null;
+	char	   *attname;
+	Oid			atttypid;
+	int32		atttypmod;
+	Oid			attcollation;
+	int			attdim;
+
+	/*
+	 * allocate a new tuple descriptor
+	 */
+	natts = list_length(columns);
+	desc = CreateTemplateTupleDesc(natts);
+	has_not_null = false;
+
+	attnum = 0;
+
+	foreach(l, columns)
+	{
+		ColumnDef  *entry = lfirst(l);
+		AclResult	aclresult;
+		Form_pg_attribute att;
+
+		/*
+		 * for each entry in the list, get the name and type information from
+		 * the list and have TupleDescInitEntry fill in the attribute
+		 * information we need.
+		 */
+		attnum++;
+
+		attname = entry->colname;
+		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
+
+		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error_type(aclresult, atttypid);
+
+		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
+		attdim = list_length(entry->typeName->arrayBounds);
+		if (attdim > PG_INT16_MAX)
+			ereport(ERROR,
+					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+					errmsg("too many array dimensions"));
+
+		if (entry->typeName->setof)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("column \"%s\" cannot be declared SETOF",
+							attname)));
+
+		TupleDescInitEntry(desc, attnum, attname,
+						   atttypid, atttypmod, attdim);
+		att = TupleDescAttr(desc, attnum - 1);
+
+		/* Override TupleDescInitEntry's settings as requested */
+		TupleDescInitEntryCollation(desc, attnum, attcollation);
+		if (entry->storage)
+			att->attstorage = entry->storage;
+
+		/* Fill in additional stuff not handled by TupleDescInitEntry */
+		att->attnotnull = entry->is_not_null;
+		has_not_null |= entry->is_not_null;
+		att->attislocal = entry->is_local;
+		att->attinhcount = entry->inhcount;
+		att->attidentity = entry->identity;
+		att->attgenerated = entry->generated;
+	}
+
+	if (has_not_null)
+	{
+		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
+
+		constr->has_not_null = true;
+		constr->has_generated_stored = false;
+		constr->defval = NULL;
+		constr->missing = NULL;
+		constr->num_defval = 0;
+		constr->check = NULL;
+		constr->num_check = 0;
+		desc->constr = constr;
+	}
+	else
+	{
+		desc->constr = NULL;
+	}
+
+	return desc;
+}
+
 /*
  * Emit the right error or warning message for a "DROP" command issued on a
  * non-existent relation
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index ffd2874ee3..d833d5f2e1 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -147,8 +147,6 @@ extern void TupleDescInitEntryCollation(TupleDesc desc,
 										AttrNumber attributeNumber,
 										Oid collationid);
 
-extern TupleDesc BuildDescForRelation(const List *columns);
-
 extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
 extern Node *TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index 16b6126669..a9c6825601 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -27,6 +27,8 @@ struct AlterTableUtilityContext;	/* avoid including tcop/utility.h here */
 extern ObjectAddress DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 									ObjectAddress *typaddress, const char *queryString);
 
+extern TupleDesc BuildDescForRelation(const List *columns);
+
 extern void RemoveRelations(DropStmt *drop);
 
 extern Oid	AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode);
-- 
2.41.0

From 25a061ebb79c1ff21076976f55ecbb4f14ba28ce Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 08/10] Push attcompression and attstorage handling into
 BuildDescForRelation()

This was previously handled by the callers but it can be moved into a
common place.
---
 src/backend/commands/tablecmds.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 0577e29230..cd6c46e866 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -941,10 +941,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			attr->atthasdef = true;
 		}
-
-		attr->attcompression = GetAttributeCompression(attr->atttypid, colDef->compression);
-		if (colDef->storage_name)
-			attr->attstorage = GetAttributeStorage(attr->atttypid, colDef->storage_name);
 	}
 
 	/*
@@ -1347,8 +1343,6 @@ BuildDescForRelation(const List *columns)
 
 		/* Override TupleDescInitEntry's settings as requested */
 		TupleDescInitEntryCollation(desc, attnum, attcollation);
-		if (entry->storage)
-			att->attstorage = entry->storage;
 
 		/* Fill in additional stuff not handled by TupleDescInitEntry */
 		att->attnotnull = entry->is_not_null;
@@ -1357,6 +1351,11 @@ BuildDescForRelation(const List *columns)
 		att->attinhcount = entry->inhcount;
 		att->attidentity = entry->identity;
 		att->attgenerated = entry->generated;
+		att->attcompression = GetAttributeCompression(att->atttypid, entry->compression);
+		if (entry->storage)
+			att->attstorage = entry->storage;
+		else if (entry->storage_name)
+			att->attstorage = GetAttributeStorage(att->atttypid, entry->storage_name);
 	}
 
 	if (has_not_null)
-- 
2.41.0

From 1dec488260cd85a2723acf6fafef5f7b93373534 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v2 09/10] Refactor ATExecAddColumn() to use
 BuildDescForRelation()

BuildDescForRelation() has all the knowledge for converting a
ColumnDef into pg_attribute/tuple descriptor.  ATExecAddColumn() can
make use of that, instead of duplicating all that logic.  We just pass
a one-element list of ColumnDef and we get back exactly the data
structure we need.  Note that we don't even need to touch
BuildDescForRelation() to make this work.
---
 src/backend/commands/tablecmds.c | 89 ++++++++------------------------
 1 file changed, 22 insertions(+), 67 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cd6c46e866..1c70cf7af5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6968,22 +6968,15 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	Relation	pgclass,
 				attrdesc;
 	HeapTuple	reltup;
-	FormData_pg_attribute attribute;
+	Form_pg_attribute attribute;
 	int			newattnum;
 	char		relkind;
-	HeapTuple	typeTuple;
-	Oid			typeOid;
-	int32		typmod;
-	Oid			collOid;
-	Form_pg_type tform;
 	Expr	   *defval;
 	List	   *children;
 	ListCell   *child;
 	AlterTableCmd *childcmd;
-	AclResult	aclresult;
 	ObjectAddress address;
 	TupleDesc	tupdesc;
-	FormData_pg_attribute *aattr[] = {&attribute};
 
 	/* At top level, permission check was done in ATPrepCmd, else do it */
 	if (recursing)
@@ -7105,59 +7098,21 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				 errmsg("tables can have at most %d columns",
 						MaxHeapAttributeNumber)));
 
-	typeTuple = typenameType(NULL, colDef->typeName, &typmod);
-	tform = (Form_pg_type) GETSTRUCT(typeTuple);
-	typeOid = tform->oid;
+	/*
+	 * Construct new attribute's pg_attribute entry.
+	 */
+	tupdesc = BuildDescForRelation(list_make1(colDef));
 
-	aclresult = object_aclcheck(TypeRelationId, typeOid, GetUserId(), ACL_USAGE);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error_type(aclresult, typeOid);
+	attribute = TupleDescAttr(tupdesc, 0);
 
-	collOid = GetColumnDefCollation(NULL, colDef, typeOid);
+	/* Fix up attribute number */
+	attribute->attnum = newattnum;
 
 	/* make sure datatype is legal for a column */
-	CheckAttributeType(colDef->colname, typeOid, collOid,
+	CheckAttributeType(NameStr(attribute->attname), attribute->atttypid, attribute->attcollation,
 					   list_make1_oid(rel->rd_rel->reltype),
 					   0);
 
-	/*
-	 * Construct new attribute's pg_attribute entry.  (Variable-length fields
-	 * are handled by InsertPgAttributeTuples().)
-	 */
-	attribute.attrelid = myrelid;
-	namestrcpy(&(attribute.attname), colDef->colname);
-	attribute.atttypid = typeOid;
-	attribute.attstattarget = -1;
-	attribute.attlen = tform->typlen;
-	attribute.attnum = newattnum;
-	if (list_length(colDef->typeName->arrayBounds) > PG_INT16_MAX)
-		ereport(ERROR,
-				errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-				errmsg("too many array dimensions"));
-	attribute.attndims = list_length(colDef->typeName->arrayBounds);
-	attribute.atttypmod = typmod;
-	attribute.attbyval = tform->typbyval;
-	attribute.attalign = tform->typalign;
-	if (colDef->storage_name)
-		attribute.attstorage = GetAttributeStorage(typeOid, colDef->storage_name);
-	else
-		attribute.attstorage = tform->typstorage;
-	attribute.attcompression = GetAttributeCompression(typeOid,
-													   colDef->compression);
-	attribute.attnotnull = colDef->is_not_null;
-	attribute.atthasdef = false;
-	attribute.atthasmissing = false;
-	attribute.attidentity = colDef->identity;
-	attribute.attgenerated = colDef->generated;
-	attribute.attisdropped = false;
-	attribute.attislocal = colDef->is_local;
-	attribute.attinhcount = colDef->inhcount;
-	attribute.attcollation = collOid;
-
-	ReleaseSysCache(typeTuple);
-
-	tupdesc = CreateTupleDesc(lengthof(aattr), (FormData_pg_attribute **) &aattr);
-
 	InsertPgAttributeTuples(attrdesc, tupdesc, myrelid, NULL, NULL);
 
 	table_close(attrdesc, RowExclusiveLock);
@@ -7187,7 +7142,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		RawColumnDefault *rawEnt;
 
 		rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
-		rawEnt->attnum = attribute.attnum;
+		rawEnt->attnum = attribute->attnum;
 		rawEnt->raw_default = copyObject(colDef->raw_default);
 
 		/*
@@ -7261,7 +7216,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NextValueExpr *nve = makeNode(NextValueExpr);
 
 			nve->seqid = RangeVarGetRelid(colDef->identitySequence, NoLock, false);
-			nve->typeId = typeOid;
+			nve->typeId = attribute->atttypid;
 
 			defval = (Expr *) nve;
 
@@ -7269,23 +7224,23 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 		}
 		else
-			defval = (Expr *) build_column_default(rel, attribute.attnum);
+			defval = (Expr *) build_column_default(rel, attribute->attnum);
 
-		if (!defval && DomainHasConstraints(typeOid))
+		if (!defval && DomainHasConstraints(attribute->atttypid))
 		{
 			Oid			baseTypeId;
 			int32		baseTypeMod;
 			Oid			baseTypeColl;
 
-			baseTypeMod = typmod;
-			baseTypeId = getBaseTypeAndTypmod(typeOid, &baseTypeMod);
+			baseTypeMod = attribute->atttypmod;
+			baseTypeId = getBaseTypeAndTypmod(attribute->atttypid, &baseTypeMod);
 			baseTypeColl = get_typcollation(baseTypeId);
 			defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod, baseTypeColl);
 			defval = (Expr *) coerce_to_target_type(NULL,
 													(Node *) defval,
 													baseTypeId,
-													typeOid,
-													typmod,
+													attribute->atttypid,
+													attribute->atttypmod,
 													COERCION_ASSIGNMENT,
 													COERCE_IMPLICIT_CAST,
 													-1);
@@ -7298,17 +7253,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NewColumnValue *newval;
 
 			newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
-			newval->attnum = attribute.attnum;
+			newval->attnum = attribute->attnum;
 			newval->expr = expression_planner(defval);
 			newval->is_generated = (colDef->generated != '\0');
 
 			tab->newvals = lappend(tab->newvals, newval);
 		}
 
-		if (DomainHasConstraints(typeOid))
+		if (DomainHasConstraints(attribute->atttypid))
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
-		if (!TupleDescAttr(rel->rd_att, attribute.attnum - 1)->atthasmissing)
+		if (!TupleDescAttr(rel->rd_att, attribute->attnum - 1)->atthasmissing)
 		{
 			/*
 			 * If the new column is NOT NULL, and there is no missing value,
@@ -7321,8 +7276,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Add needed dependency entries for the new column.
 	 */
-	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
-	add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
+	add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid);
+	add_column_collation_dependency(myrelid, newattnum, attribute->attcollation);
 
 	/*
 	 * Propagate to children as appropriate.  Unlike most other ALTER
-- 
2.41.0

commit 50ac445d1e1ad84282d59c09a3937c221d94b968
Author:     Alvaro Herrera <alvherre@alvh.no-ip.org> [Álvaro Herrera <alvherre@alvh.no-ip.org>]
AuthorDate: Wed Aug 30 16:09:52 2023 +0200
CommitDate: Wed Aug 30 16:41:06 2023 +0200

    seq-warnings

diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 0b0003fcc8..4798c9cd20 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -129,11 +129,16 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	Relation	rel;
 	HeapTuple	tuple;
 	TupleDesc	tupDesc;
-	Datum		value[SEQ_COL_LASTCOL];
-	bool		null[SEQ_COL_LASTCOL];
 	Datum		pgs_values[Natts_pg_sequence];
 	bool		pgs_nulls[Natts_pg_sequence];
-	int			i;
+	struct SequenceColumn
+	{
+		const char *name;
+		Oid			type;
+		Datum		init_value;
+	}			sequence_cols[3];
+	Datum		value[3];
+	bool		null[3];
 
 	/*
 	 * If if_not_exists was given and a relation with the same name already
@@ -166,32 +171,39 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 				&seqform, &seqdataform,
 				&need_seq_rewrite, &owned_by);
 
+	sequence_cols[0] = (struct SequenceColumn)
+	{
+		.name = "last_value",
+			.type = INT8OID,
+			.init_value = Int64GetDatumFast(seqdataform.last_value)
+	};
+	sequence_cols[1] = (struct SequenceColumn)
+	{
+		.name = "log_cnt",
+			.type = INT8OID,
+			.init_value = Int64GetDatum((int64) 0)
+	};
+	sequence_cols[2] = (struct SequenceColumn)
+	{
+		.name = "is_called",
+			.type = BOOLOID,
+			.init_value = BoolGetDatum(false)
+	};
+
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
 	 */
 	stmt->tableElts = NIL;
-	for (i = SEQ_COL_FIRSTCOL; i <= SEQ_COL_LASTCOL; i++)
+	for (int i = 0; i < lengthof(sequence_cols); i++)
 	{
 		ColumnDef  *coldef;
 
-		switch (i)
-		{
-			case SEQ_COL_LASTVAL:
-				coldef = makeColumnDef("last_value", INT8OID, -1, InvalidOid);
-				value[i - 1] = Int64GetDatumFast(seqdataform.last_value);
-				break;
-			case SEQ_COL_LOG:
-				coldef = makeColumnDef("log_cnt", INT8OID, -1, InvalidOid);
-				value[i - 1] = Int64GetDatum((int64) 0);
-				break;
-			case SEQ_COL_CALLED:
-				coldef = makeColumnDef("is_called", BOOLOID, -1, InvalidOid);
-				value[i - 1] = BoolGetDatum(false);
-				break;
-		}
-
+		coldef = makeColumnDef(sequence_cols[i].name, sequence_cols[i].type, -1,
+							   InvalidOid);
 		coldef->is_not_null = true;
-		null[i - 1] = false;
+
+		value[i] = sequence_cols[i].init_value;
+		null[i] = false;
 
 		stmt->tableElts = lappend(stmt->tableElts, coldef);
 	}
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 7db7b3da7b..784280b26d 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -31,17 +31,6 @@ typedef struct FormData_pg_sequence_data
 
 typedef FormData_pg_sequence_data *Form_pg_sequence_data;
 
-/*
- * Columns of a sequence relation
- */
-
-#define SEQ_COL_LASTVAL			1
-#define SEQ_COL_LOG				2
-#define SEQ_COL_CALLED			3
-
-#define SEQ_COL_FIRSTCOL		SEQ_COL_LASTVAL
-#define SEQ_COL_LASTCOL			SEQ_COL_CALLED
-
 /* XLOG stuff */
 #define XLOG_SEQ_LOG			0x00
 

From 28e4dbba35fc3162c13f5896551921896cf30d1c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v3 1/9] Clean up MergeAttributesIntoExisting()

Make variable naming clearer and more consistent.  Move some variables
to smaller scope.  Remove some unnecessary intermediate variables.
Try to save some vertical space.

Apply analogous changes to nearby MergeConstraintsIntoExisting() and
RemoveInheritance() for consistency.
---
 src/backend/commands/tablecmds.c | 123 ++++++++++++-------------------
 1 file changed, 48 insertions(+), 75 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 8a2c671b66..ff001f5ceb 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -15695,53 +15695,39 @@ static void
 MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 {
 	Relation	attrrel;
-	AttrNumber	parent_attno;
-	int			parent_natts;
-	TupleDesc	tupleDesc;
-	HeapTuple	tuple;
-	bool		child_is_partition = false;
+	TupleDesc	parent_desc;
 
 	attrrel = table_open(AttributeRelationId, RowExclusiveLock);
+	parent_desc = RelationGetDescr(parent_rel);
 
-	tupleDesc = RelationGetDescr(parent_rel);
-	parent_natts = tupleDesc->natts;
-
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
-
-	for (parent_attno = 1; parent_attno <= parent_natts; parent_attno++)
+	for (AttrNumber parent_attno = 1; parent_attno <= parent_desc->natts; parent_attno++)
 	{
-		Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
-													parent_attno - 1);
-		char	   *attributeName = NameStr(attribute->attname);
+		Form_pg_attribute parent_att = TupleDescAttr(parent_desc, parent_attno - 1);
+		char	   *parent_attname = NameStr(parent_att->attname);
+		HeapTuple	tuple;
 
 		/* Ignore dropped columns in the parent. */
-		if (attribute->attisdropped)
+		if (parent_att->attisdropped)
 			continue;
 
 		/* Find same column in child (matching on column name). */
-		tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel),
-										  attributeName);
+		tuple = SearchSysCacheCopyAttName(RelationGetRelid(child_rel), parent_attname);
 		if (HeapTupleIsValid(tuple))
 		{
-			/* Check they are same type, typmod, and collation */
-			Form_pg_attribute childatt = (Form_pg_attribute) GETSTRUCT(tuple);
+			Form_pg_attribute child_att = (Form_pg_attribute) GETSTRUCT(tuple);
 
-			if (attribute->atttypid != childatt->atttypid ||
-				attribute->atttypmod != childatt->atttypmod)
+			if (parent_att->atttypid != child_att->atttypid ||
+				parent_att->atttypmod != child_att->atttypmod)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different type for column \"%s\"",
-								RelationGetRelationName(child_rel),
-								attributeName)));
+								RelationGetRelationName(child_rel), parent_attname)));
 
-			if (attribute->attcollation != childatt->attcollation)
+			if (parent_att->attcollation != child_att->attcollation)
 				ereport(ERROR,
 						(errcode(ERRCODE_COLLATION_MISMATCH),
 						 errmsg("child table \"%s\" has different collation for column \"%s\"",
-								RelationGetRelationName(child_rel),
-								attributeName)));
+								RelationGetRelationName(child_rel), parent_attname)));
 
 			/*
 			 * If the parent has a not-null constraint that's not NO INHERIT,
@@ -15749,40 +15735,38 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 			 *
 			 * Other constraints are checked elsewhere.
 			 */
-			if (attribute->attnotnull && !childatt->attnotnull)
+			if (parent_att->attnotnull && !child_att->attnotnull)
 			{
 				HeapTuple	contup;
 
 				contup = findNotNullConstraintAttnum(RelationGetRelid(parent_rel),
-													 attribute->attnum);
+													 parent_att->attnum);
 				if (HeapTupleIsValid(contup) &&
 					!((Form_pg_constraint) GETSTRUCT(contup))->connoinherit)
 					ereport(ERROR,
 							errcode(ERRCODE_DATATYPE_MISMATCH),
 							errmsg("column \"%s\" in child table must be marked NOT NULL",
-								   attributeName));
+								   parent_attname));
 			}
 
 			/*
 			 * Child column must be generated if and only if parent column is.
 			 */
-			if (attribute->attgenerated && !childatt->attgenerated)
+			if (parent_att->attgenerated && !child_att->attgenerated)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("column \"%s\" in child table must be a generated column",
-								attributeName)));
-			if (childatt->attgenerated && !attribute->attgenerated)
+						 errmsg("column \"%s\" in child table must be a generated column", parent_attname)));
+			if (child_att->attgenerated && !parent_att->attgenerated)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
-						 errmsg("column \"%s\" in child table must not be a generated column",
-								attributeName)));
+						 errmsg("column \"%s\" in child table must not be a generated column", parent_attname)));
 
 			/*
 			 * OK, bump the child column's inheritance count.  (If we fail
 			 * later on, this change will just roll back.)
 			 */
-			childatt->attinhcount++;
-			if (childatt->attinhcount < 0)
+			child_att->attinhcount++;
+			if (child_att->attinhcount < 0)
 				ereport(ERROR,
 						errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 						errmsg("too many inheritance parents"));
@@ -15792,10 +15776,10 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 			 * is same in all partitions. (Note: there are only inherited
 			 * attributes in partitions)
 			 */
-			if (child_is_partition)
+			if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 			{
-				Assert(childatt->attinhcount == 1);
-				childatt->attislocal = false;
+				Assert(child_att->attinhcount == 1);
+				child_att->attislocal = false;
 			}
 
 			CatalogTupleUpdate(attrrel, &tuple->t_self, tuple);
@@ -15805,8 +15789,7 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 		{
 			ereport(ERROR,
 					(errcode(ERRCODE_DATATYPE_MISMATCH),
-					 errmsg("child table is missing column \"%s\"",
-							attributeName)));
+					 errmsg("child table is missing column \"%s\"", parent_attname)));
 		}
 	}
 
@@ -15833,27 +15816,20 @@ MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel)
 static void
 MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 {
-	Relation	catalog_relation;
-	TupleDesc	tuple_desc;
+	Relation	constraintrel;
 	SysScanDesc parent_scan;
 	ScanKeyData parent_key;
 	HeapTuple	parent_tuple;
 	Oid			parent_relid = RelationGetRelid(parent_rel);
-	bool		child_is_partition = false;
 
-	catalog_relation = table_open(ConstraintRelationId, RowExclusiveLock);
-	tuple_desc = RelationGetDescr(catalog_relation);
-
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
+	constraintrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
 	/* Outer loop scans through the parent's constraint definitions */
 	ScanKeyInit(&parent_key,
 				Anum_pg_constraint_conrelid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(parent_relid));
-	parent_scan = systable_beginscan(catalog_relation, ConstraintRelidTypidNameIndexId,
+	parent_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
 									 true, NULL, 1, &parent_key);
 
 	while (HeapTupleIsValid(parent_tuple = systable_getnext(parent_scan)))
@@ -15877,7 +15853,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 					Anum_pg_constraint_conrelid,
 					BTEqualStrategyNumber, F_OIDEQ,
 					ObjectIdGetDatum(RelationGetRelid(child_rel)));
-		child_scan = systable_beginscan(catalog_relation, ConstraintRelidTypidNameIndexId,
+		child_scan = systable_beginscan(constraintrel, ConstraintRelidTypidNameIndexId,
 										true, NULL, 1, &child_key);
 
 		while (HeapTupleIsValid(child_tuple = systable_getnext(child_scan)))
@@ -15892,10 +15868,12 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			 * CHECK constraint are matched by name, NOT NULL ones by
 			 * attribute number
 			 */
-			if (child_con->contype == CONSTRAINT_CHECK &&
-				strcmp(NameStr(parent_con->conname),
-					   NameStr(child_con->conname)) != 0)
-				continue;
+			if (child_con->contype == CONSTRAINT_CHECK)
+			{
+				if (strcmp(NameStr(parent_con->conname),
+						   NameStr(child_con->conname)) != 0)
+					continue;
+			}
 			else if (child_con->contype == CONSTRAINT_NOTNULL)
 			{
 				AttrNumber	parent_attno = extractNotNullColumn(parent_tuple);
@@ -15908,12 +15886,11 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			}
 
 			if (child_con->contype == CONSTRAINT_CHECK &&
-				!constraints_equivalent(parent_tuple, child_tuple, tuple_desc))
+				!constraints_equivalent(parent_tuple, child_tuple, RelationGetDescr(constraintrel)))
 				ereport(ERROR,
 						(errcode(ERRCODE_DATATYPE_MISMATCH),
 						 errmsg("child table \"%s\" has different definition for check constraint \"%s\"",
-								RelationGetRelationName(child_rel),
-								NameStr(parent_con->conname))));
+								RelationGetRelationName(child_rel), NameStr(parent_con->conname))));
 
 			/*
 			 * If the CHECK child constraint is "no inherit" then cannot
@@ -15931,8 +15908,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 						 errmsg("constraint \"%s\" conflicts with non-inherited constraint on child table \"%s\"",
-								NameStr(child_con->conname),
-								RelationGetRelationName(child_rel))));
+								NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
 			/*
 			 * If the child constraint is "not valid" then cannot merge with a
@@ -15942,8 +15918,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
 						 errmsg("constraint \"%s\" conflicts with NOT VALID constraint on child table \"%s\"",
-								NameStr(child_con->conname),
-								RelationGetRelationName(child_rel))));
+								NameStr(child_con->conname), RelationGetRelationName(child_rel))));
 
 			/*
 			 * OK, bump the child constraint's inheritance count.  (If we fail
@@ -15965,13 +15940,13 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 			 * inherited only once since it cannot have multiple parents and
 			 * it is never considered local.
 			 */
-			if (child_is_partition)
+			if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
 			{
 				Assert(child_con->coninhcount == 1);
 				child_con->conislocal = false;
 			}
 
-			CatalogTupleUpdate(catalog_relation, &child_copy->t_self, child_copy);
+			CatalogTupleUpdate(constraintrel, &child_copy->t_self, child_copy);
 			heap_freetuple(child_copy);
 
 			found = true;
@@ -15998,7 +15973,7 @@ MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel)
 	}
 
 	systable_endscan(parent_scan);
-	table_close(catalog_relation, RowExclusiveLock);
+	table_close(constraintrel, RowExclusiveLock);
 }
 
 /*
@@ -16154,11 +16129,9 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 	List	   *connames;
 	List	   *nncolumns;
 	bool		found;
-	bool		child_is_partition = false;
+	bool		is_partitioning;
 
-	/* If parent_rel is a partitioned table, child_rel must be a partition */
-	if (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
-		child_is_partition = true;
+	is_partitioning = (parent_rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE);
 
 	found = DeleteInheritsTuple(RelationGetRelid(child_rel),
 								RelationGetRelid(parent_rel),
@@ -16166,7 +16139,7 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 								RelationGetRelationName(child_rel));
 	if (!found)
 	{
-		if (child_is_partition)
+		if (is_partitioning)
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_TABLE),
 					 errmsg("relation \"%s\" is not a partition of relation \"%s\"",
@@ -16320,7 +16293,7 @@ RemoveInheritance(Relation child_rel, Relation parent_rel, bool expect_detached)
 	drop_parent_dependency(RelationGetRelid(child_rel),
 						   RelationRelationId,
 						   RelationGetRelid(parent_rel),
-						   child_dependency_type(child_is_partition));
+						   child_dependency_type(is_partitioning));
 
 	/*
 	 * Post alter hook of this inherits. Since object_access_hook doesn't take
-- 
2.42.0

From c5653b746bd8611c7297fb43013ab4f8adee8b40 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v3 2/9] Clean up MergeCheckConstraint()

If the constraint is not already in the list, add it ourselves,
instead of making the caller do it.  This makes the interface more
consistent with other "merge" functions in this file.
---
 src/backend/commands/tablecmds.c | 48 +++++++++++++++-----------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ff001f5ceb..b73f4c96a4 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -353,7 +353,7 @@ static void RangeVarCallbackForTruncate(const RangeVar *relation,
 static List *MergeAttributes(List *schema, List *supers, char relpersistence,
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
-static bool MergeCheckConstraint(List *constraints, char *name, Node *expr);
+static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
 static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel);
 static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
 static void StoreCatalogInheritance(Oid relationId, List *supers,
@@ -2913,24 +2913,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   name,
 									   RelationGetRelationName(relation))));
 
-				/* check for duplicate */
-				if (!MergeCheckConstraint(constraints, name, expr))
-				{
-					/* nope, this is a new one */
-					CookedConstraint *cooked;
-
-					cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
-					cooked->contype = CONSTR_CHECK;
-					cooked->conoid = InvalidOid;	/* until created */
-					cooked->name = pstrdup(name);
-					cooked->attnum = 0; /* not used for constraints */
-					cooked->expr = expr;
-					cooked->skip_validation = false;
-					cooked->is_local = false;
-					cooked->inhcount = 1;
-					cooked->is_no_inherit = false;
-					constraints = lappend(constraints, cooked);
-				}
+				constraints = MergeCheckConstraint(constraints, name, expr);
 			}
 		}
 
@@ -3277,13 +3260,17 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
  *
  * constraints is a list of CookedConstraint structs for previous constraints.
  *
- * Returns true if merged (constraint is a duplicate), or false if it's
- * got a so-far-unique name, or throws error if conflict.
+ * If the new constraint matches an existing one, then the existing
+ * constraint's inheritance count is updated.  If there is a conflict (same
+ * name but different expression), throw an error.  If the constraint neither
+ * matches nor conflicts with an existing one, a new constraint is appended to
+ * the list.
  */
-static bool
-MergeCheckConstraint(List *constraints, char *name, Node *expr)
+static List *
+MergeCheckConstraint(List *constraints, const char *name, Node *expr)
 {
 	ListCell   *lc;
+	CookedConstraint *newcon;
 
 	foreach(lc, constraints)
 	{
@@ -3297,13 +3284,13 @@ MergeCheckConstraint(List *constraints, char *name, Node *expr)
 
 		if (equal(expr, ccon->expr))
 		{
-			/* OK to merge */
+			/* OK to merge constraint with existing */
 			ccon->inhcount++;
 			if (ccon->inhcount < 0)
 				ereport(ERROR,
 						errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 						errmsg("too many inheritance parents"));
-			return true;
+			return constraints;
 		}
 
 		ereport(ERROR,
@@ -3312,7 +3299,16 @@ MergeCheckConstraint(List *constraints, char *name, Node *expr)
 						name)));
 	}
 
-	return false;
+	/*
+	 * Constraint couldn't be merged with an existing one and also didn't
+	 * conflict with an existing one, so add it as a new one to the list.
+	 */
+	newcon = palloc0_object(CookedConstraint);
+	newcon->contype = CONSTR_CHECK;
+	newcon->name = pstrdup(name);
+	newcon->expr = expr;
+	newcon->inhcount = 1;
+	return lappend(constraints, newcon);
 }
 
 
-- 
2.42.0

From b558f35954be5c232d4ff2bb23313d6ce0cceb49 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:34 +0200
Subject: [PATCH v3 3/9] MergeAttributes() and related variable renaming

Mainly, rename "schema" to "columns" and related changes.  The
previous naming has long been confusing.
---
 src/backend/access/common/tupdesc.c |  10 +--
 src/backend/commands/tablecmds.c    | 109 +++++++++++++---------------
 src/include/access/tupdesc.h        |   4 +-
 3 files changed, 59 insertions(+), 64 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 7c5c390503..253d6c86f8 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -782,12 +782,12 @@ TupleDescInitEntryCollation(TupleDesc desc,
 /*
  * BuildDescForRelation
  *
- * Given a relation schema (list of ColumnDef nodes), build a TupleDesc.
+ * Given a list of ColumnDef nodes, build a TupleDesc.
  *
  * Note: tdtypeid will need to be filled in later on.
  */
 TupleDesc
-BuildDescForRelation(List *schema)
+BuildDescForRelation(const List *columns)
 {
 	int			natts;
 	AttrNumber	attnum;
@@ -803,13 +803,13 @@ BuildDescForRelation(List *schema)
 	/*
 	 * allocate a new tuple descriptor
 	 */
-	natts = list_length(schema);
+	natts = list_length(columns);
 	desc = CreateTemplateTupleDesc(natts);
 	has_not_null = false;
 
 	attnum = 0;
 
-	foreach(l, schema)
+	foreach(l, columns)
 	{
 		ColumnDef  *entry = lfirst(l);
 		AclResult	aclresult;
@@ -891,7 +891,7 @@ BuildDescForRelation(List *schema)
  * with functions returning RECORD.
  */
 TupleDesc
-BuildDescFromLists(List *names, List *types, List *typmods, List *collations)
+BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)
 {
 	int			natts;
 	AttrNumber	attnum;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b73f4c96a4..ad398e837d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -350,7 +350,7 @@ static void truncate_check_perms(Oid relid, Form_pg_class reltuple);
 static void truncate_check_activity(Relation rel);
 static void RangeVarCallbackForTruncate(const RangeVar *relation,
 										Oid relId, Oid oldRelId, void *arg);
-static List *MergeAttributes(List *schema, List *supers, char relpersistence,
+static List *MergeAttributes(List *columns, const List *supers, char relpersistence,
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
 static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
@@ -361,7 +361,7 @@ static void StoreCatalogInheritance(Oid relationId, List *supers,
 static void StoreCatalogInheritance1(Oid relationId, Oid parentOid,
 									 int32 seqNumber, Relation inhRelation,
 									 bool child_is_partition);
-static int	findAttrByName(const char *attributeName, List *schema);
+static int	findAttrByName(const char *attributeName, const List *columns);
 static void AlterIndexNamespaces(Relation classRel, Relation rel,
 								 Oid oldNspOid, Oid newNspOid, ObjectAddresses *objsMoved);
 static void AlterSeqNamespaces(Relation classRel, Relation rel,
@@ -2307,7 +2307,7 @@ storage_name(char c)
  *		Returns new schema given initial schema and superclasses.
  *
  * Input arguments:
- * 'schema' is the column/attribute definition for the table. (It's a list
+ * 'columns' is the column/attribute definition for the table. (It's a list
  *		of ColumnDef's.) It is destructively changed.
  * 'supers' is a list of OIDs of parent relations, already locked by caller.
  * 'relpersistence' is the persistence type of the table.
@@ -2369,17 +2369,17 @@ storage_name(char c)
  *----------
  */
 static List *
-MergeAttributes(List *schema, List *supers, char relpersistence,
+MergeAttributes(List *columns, const List *supers, char relpersistence,
 				bool is_partition, List **supconstr, List **supnotnulls)
 {
-	List	   *inhSchema = NIL;
+	List	   *inh_columns = NIL;
 	List	   *constraints = NIL;
 	List	   *nnconstraints = NIL;
 	bool		have_bogus_defaults = false;
 	int			child_attno;
 	static Node bogus_marker = {0}; /* marks conflicting defaults */
-	List	   *saved_schema = NIL;
-	ListCell   *entry;
+	List	   *saved_columns = NIL;
+	ListCell   *lc;
 
 	/*
 	 * Check for and reject tables with too many columns. We perform this
@@ -2392,7 +2392,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 * Note that we also need to check that we do not exceed this figure after
 	 * including columns from inherited relations.
 	 */
-	if (list_length(schema) > MaxHeapAttributeNumber)
+	if (list_length(columns) > MaxHeapAttributeNumber)
 		ereport(ERROR,
 				(errcode(ERRCODE_TOO_MANY_COLUMNS),
 				 errmsg("tables can have at most %d columns",
@@ -2406,15 +2406,15 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 * sense to assume such conflicts are errors.
 	 *
 	 * We don't use foreach() here because we have two nested loops over the
-	 * schema list, with possible element deletions in the inner one.  If we
+	 * columns list, with possible element deletions in the inner one.  If we
 	 * used foreach_delete_current() it could only fix up the state of one of
 	 * the loops, so it seems cleaner to use looping over list indexes for
 	 * both loops.  Note that any deletion will happen beyond where the outer
 	 * loop is, so its index never needs adjustment.
 	 */
-	for (int coldefpos = 0; coldefpos < list_length(schema); coldefpos++)
+	for (int coldefpos = 0; coldefpos < list_length(columns); coldefpos++)
 	{
-		ColumnDef  *coldef = list_nth_node(ColumnDef, schema, coldefpos);
+		ColumnDef  *coldef = list_nth_node(ColumnDef, columns, coldefpos);
 
 		if (!is_partition && coldef->typeName == NULL)
 		{
@@ -2431,9 +2431,9 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		}
 
 		/* restpos scans all entries beyond coldef; incr is in loop body */
-		for (int restpos = coldefpos + 1; restpos < list_length(schema);)
+		for (int restpos = coldefpos + 1; restpos < list_length(columns);)
 		{
-			ColumnDef  *restdef = list_nth_node(ColumnDef, schema, restpos);
+			ColumnDef  *restdef = list_nth_node(ColumnDef, columns, restpos);
 
 			if (strcmp(coldef->colname, restdef->colname) == 0)
 			{
@@ -2447,7 +2447,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 					coldef->cooked_default = restdef->cooked_default;
 					coldef->constraints = restdef->constraints;
 					coldef->is_from_type = false;
-					schema = list_delete_nth_cell(schema, restpos);
+					columns = list_delete_nth_cell(columns, restpos);
 				}
 				else
 					ereport(ERROR,
@@ -2467,18 +2467,18 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (is_partition)
 	{
-		saved_schema = schema;
-		schema = NIL;
+		saved_columns = columns;
+		columns = NIL;
 	}
 
 	/*
 	 * Scan the parents left-to-right, and merge their attributes to form a
-	 * list of inherited attributes (inhSchema).
+	 * list of inherited columns (inh_columns).
 	 */
 	child_attno = 0;
-	foreach(entry, supers)
+	foreach(lc, supers)
 	{
-		Oid			parent = lfirst_oid(entry);
+		Oid			parent = lfirst_oid(lc);
 		Relation	relation;
 		TupleDesc	tupleDesc;
 		TupleConstr *constr;
@@ -2486,7 +2486,6 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		List	   *inherited_defaults;
 		List	   *cols_with_defaults;
 		List	   *nnconstrs;
-		AttrNumber	parent_attno;
 		ListCell   *lc1;
 		ListCell   *lc2;
 		Bitmapset  *pkattrs;
@@ -2507,8 +2506,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		 * We do not allow partitioned tables and partitions to participate in
 		 * regular inheritance.
 		 */
-		if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE &&
-			!is_partition)
+		if (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE && !is_partition)
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 					 errmsg("cannot inherit from partitioned table \"%s\"",
@@ -2593,7 +2591,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			nncols = bms_add_member(nncols,
 									((CookedConstraint *) lfirst(lc1))->attnum);
 
-		for (parent_attno = 1; parent_attno <= tupleDesc->natts;
+		for (AttrNumber parent_attno = 1; parent_attno <= tupleDesc->natts;
 			 parent_attno++)
 		{
 			Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
@@ -2611,7 +2609,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			/*
 			 * Does it conflict with some previously inherited column?
 			 */
-			exist_attno = findAttrByName(attributeName, inhSchema);
+			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
 				Oid			defTypeId;
@@ -2624,7 +2622,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
+				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
@@ -2761,7 +2759,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				if (CompressionMethodIsValid(attribute->attcompression))
 					def->compression =
 						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inhSchema = lappend(inhSchema, def);
+				inh_columns = lappend(inh_columns, def);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2862,7 +2860,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			 * If we already had a default from some prior parent, check to
 			 * see if they are the same.  If so, no problem; if not, mark the
 			 * column as having a bogus default.  Below, we will complain if
-			 * the bogus default isn't overridden by the child schema.
+			 * the bogus default isn't overridden by the child columns.
 			 */
 			Assert(def->raw_default == NULL);
 			if (def->cooked_default == NULL)
@@ -2882,9 +2880,8 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 		if (constr && constr->num_check > 0)
 		{
 			ConstrCheck *check = constr->check;
-			int			i;
 
-			for (i = 0; i < constr->num_check; i++)
+			for (int i = 0; i < constr->num_check; i++)
 			{
 				char	   *name = check[i].ccname;
 				Node	   *expr;
@@ -2945,27 +2942,27 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	}
 
 	/*
-	 * If we had no inherited attributes, the result schema is just the
+	 * If we had no inherited attributes, the result columns are just the
 	 * explicitly declared columns.  Otherwise, we need to merge the declared
-	 * columns into the inherited schema list.  Although, we never have any
+	 * columns into the inherited column list.  Although, we never have any
 	 * explicitly declared columns if the table is a partition.
 	 */
-	if (inhSchema != NIL)
+	if (inh_columns != NIL)
 	{
-		int			schema_attno = 0;
+		int			newcol_attno = 0;
 
-		foreach(entry, schema)
+		foreach(lc, columns)
 		{
-			ColumnDef  *newdef = lfirst(entry);
+			ColumnDef  *newdef = lfirst(lc);
 			char	   *attributeName = newdef->colname;
 			int			exist_attno;
 
-			schema_attno++;
+			newcol_attno++;
 
 			/*
 			 * Does it conflict with some previously inherited column?
 			 */
-			exist_attno = findAttrByName(attributeName, inhSchema);
+			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
 				ColumnDef  *def;
@@ -2985,7 +2982,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				/*
 				 * Yes, try to merge the two column definitions.
 				 */
-				if (exist_attno == schema_attno)
+				if (exist_attno == newcol_attno)
 					ereport(NOTICE,
 							(errmsg("merging column \"%s\" with inherited definition",
 									attributeName)));
@@ -2993,7 +2990,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inhSchema, exist_attno - 1);
+				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
@@ -3118,19 +3115,19 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 			else
 			{
 				/*
-				 * No, attach new column to result schema
+				 * No, attach new column to result columns
 				 */
-				inhSchema = lappend(inhSchema, newdef);
+				inh_columns = lappend(inh_columns, newdef);
 			}
 		}
 
-		schema = inhSchema;
+		columns = inh_columns;
 
 		/*
 		 * Check that we haven't exceeded the legal # of columns after merging
 		 * in inherited columns.
 		 */
-		if (list_length(schema) > MaxHeapAttributeNumber)
+		if (list_length(columns) > MaxHeapAttributeNumber)
 			ereport(ERROR,
 					(errcode(ERRCODE_TOO_MANY_COLUMNS),
 					 errmsg("tables can have at most %d columns",
@@ -3144,13 +3141,13 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (is_partition)
 	{
-		foreach(entry, saved_schema)
+		foreach(lc, saved_columns)
 		{
-			ColumnDef  *restdef = lfirst(entry);
+			ColumnDef  *restdef = lfirst(lc);
 			bool		found = false;
 			ListCell   *l;
 
-			foreach(l, schema)
+			foreach(l, columns)
 			{
 				ColumnDef  *coldef = lfirst(l);
 
@@ -3222,9 +3219,9 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	 */
 	if (have_bogus_defaults)
 	{
-		foreach(entry, schema)
+		foreach(lc, columns)
 		{
-			ColumnDef  *def = lfirst(entry);
+			ColumnDef  *def = lfirst(lc);
 
 			if (def->cooked_default == &bogus_marker)
 			{
@@ -3247,7 +3244,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 	*supconstr = constraints;
 	*supnotnulls = nnconstraints;
 
-	return schema;
+	return columns;
 }
 
 
@@ -3402,22 +3399,20 @@ StoreCatalogInheritance1(Oid relationId, Oid parentOid,
 }
 
 /*
- * Look for an existing schema entry with the given name.
+ * Look for an existing column entry with the given name.
  *
- * Returns the index (starting with 1) if attribute already exists in schema,
+ * Returns the index (starting with 1) if attribute already exists in columns,
  * 0 if it doesn't.
  */
 static int
-findAttrByName(const char *attributeName, List *schema)
+findAttrByName(const char *attributeName, const List *columns)
 {
-	ListCell   *s;
+	ListCell   *lc;
 	int			i = 1;
 
-	foreach(s, schema)
+	foreach(lc, columns)
 	{
-		ColumnDef  *def = lfirst(s);
-
-		if (strcmp(attributeName, def->colname) == 0)
+		if (strcmp(attributeName, lfirst_node(ColumnDef, lc)->colname) == 0)
 			return i;
 
 		i++;
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index b4286cf922..f6cc28a661 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -147,8 +147,8 @@ extern void TupleDescInitEntryCollation(TupleDesc desc,
 										AttrNumber attributeNumber,
 										Oid collationid);
 
-extern TupleDesc BuildDescForRelation(List *schema);
+extern TupleDesc BuildDescForRelation(const List *columns);
 
-extern TupleDesc BuildDescFromLists(List *names, List *types, List *typmods, List *collations);
+extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
 #endif							/* TUPDESC_H */
-- 
2.42.0

From 0a5593983555e669a9fab8e366c6a36b26ebac14 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 4/9] Add TupleDescGetDefault()

This unifies some repetitive code.

Note: I didn't push the "not found" error message into the new
function, even though all existing callers would be able to make use
of it.  Using the existing error handling as-is would probably require
exposing the Relation type via tupdesc.h, which doesn't seem
desirable.
---
 src/backend/access/common/tupdesc.c  | 25 +++++++++++++++++++++++++
 src/backend/commands/tablecmds.c     | 17 ++---------------
 src/backend/parser/parse_utilcmd.c   | 13 ++-----------
 src/backend/rewrite/rewriteHandler.c | 16 +---------------
 src/include/access/tupdesc.h         |  2 ++
 5 files changed, 32 insertions(+), 41 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 253d6c86f8..ce2c7bce85 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -927,3 +927,28 @@ BuildDescFromLists(const List *names, const List *types, const List *typmods, co
 
 	return desc;
 }
+
+/*
+ * Get default expression (or NULL if none) for the given attribute number.
+ */
+Node *
+TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum)
+{
+	Node	   *result = NULL;
+
+	if (tupdesc->constr)
+	{
+		AttrDefault *attrdef = tupdesc->constr->defval;
+
+		for (int i = 0; i < tupdesc->constr->num_defval; i++)
+		{
+			if (attrdef[i].adnum == attnum)
+			{
+				result = stringToNode(attrdef[i].adbin);
+				break;
+			}
+		}
+	}
+
+	return result;
+}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index ad398e837d..73b8dea81c 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2795,22 +2795,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			 */
 			if (attribute->atthasdef)
 			{
-				Node	   *this_default = NULL;
+				Node	   *this_default;
 
-				/* Find default in constraint structure */
-				if (constr != NULL)
-				{
-					AttrDefault *attrdef = constr->defval;
-
-					for (int i = 0; i < constr->num_defval; i++)
-					{
-						if (attrdef[i].adnum == parent_attno)
-						{
-							this_default = stringToNode(attrdef[i].adbin);
-							break;
-						}
-					}
-				}
+				this_default = TupleDescGetDefault(tupleDesc, parent_attno);
 				if (this_default == NULL)
 					elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 						 parent_attno, RelationGetRelationName(relation));
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 55c315f0e2..cf0d432ab1 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1358,20 +1358,11 @@ expandTableLikeClause(RangeVar *heapRel, TableLikeClause *table_like_clause)
 				 (table_like_clause->options & CREATE_TABLE_LIKE_GENERATED) :
 				 (table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS)))
 			{
-				Node	   *this_default = NULL;
-				AttrDefault *attrdef = constr->defval;
+				Node	   *this_default;
 				AlterTableCmd *atsubcmd;
 				bool		found_whole_row;
 
-				/* Find default in constraint structure */
-				for (int i = 0; i < constr->num_defval; i++)
-				{
-					if (attrdef[i].adnum == parent_attno)
-					{
-						this_default = stringToNode(attrdef[i].adbin);
-						break;
-					}
-				}
+				this_default = TupleDescGetDefault(tupleDesc, parent_attno);
 				if (this_default == NULL)
 					elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 						 parent_attno, RelationGetRelationName(relation));
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index b486ab559a..41a362310a 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -1246,21 +1246,7 @@ build_column_default(Relation rel, int attrno)
 	 */
 	if (att_tup->atthasdef)
 	{
-		if (rd_att->constr && rd_att->constr->num_defval > 0)
-		{
-			AttrDefault *defval = rd_att->constr->defval;
-			int			ndef = rd_att->constr->num_defval;
-
-			while (--ndef >= 0)
-			{
-				if (attrno == defval[ndef].adnum)
-				{
-					/* Found it, convert string representation to node tree. */
-					expr = stringToNode(defval[ndef].adbin);
-					break;
-				}
-			}
-		}
+		expr = TupleDescGetDefault(rd_att, attrno);
 		if (expr == NULL)
 			elog(ERROR, "default expression not found for attribute %d of relation \"%s\"",
 				 attrno, RelationGetRelationName(rel));
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index f6cc28a661..ffd2874ee3 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -151,4 +151,6 @@ extern TupleDesc BuildDescForRelation(const List *columns);
 
 extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
+extern Node *TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum);
+
 #endif							/* TUPDESC_H */
-- 
2.42.0

From 402174806f36bb1a240f5afbeacad3ffd9292a9a Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 5/9] Push attidentity and attgenerated handling into
 BuildDescForRelation()

Previously, this was handled by the callers separately, but it can be
trivially moved into BuildDescForRelation() so that it is handled in a
central place.
---
 src/backend/access/common/tupdesc.c | 2 ++
 src/backend/commands/tablecmds.c    | 2 --
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index ce2c7bce85..c2e7b14c31 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -856,6 +856,8 @@ BuildDescForRelation(const List *columns)
 		has_not_null |= entry->is_not_null;
 		att->attislocal = entry->is_local;
 		att->attinhcount = entry->inhcount;
+		att->attidentity = entry->identity;
+		att->attgenerated = entry->generated;
 	}
 
 	if (has_not_null)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 73b8dea81c..60ede984e0 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -941,8 +941,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			attr->atthasdef = true;
 		}
 
-		attr->attidentity = colDef->identity;
-		attr->attgenerated = colDef->generated;
 		attr->attcompression = GetAttributeCompression(attr->atttypid, colDef->compression);
 		if (colDef->storage_name)
 			attr->attstorage = GetAttributeStorage(attr->atttypid, colDef->storage_name);
-- 
2.42.0

From ad08dbbb459683da6206afb5cdc11164bbb94fc2 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 6/9] Move BuildDescForRelation() from tupdesc.c to
 tablecmds.c

BuildDescForRelation() main job is to convert ColumnDef lists to
pg_attribute/tuple descriptor arrays, which is really mostly an
internal subroutine of DefineRelation() and some related functions,
which is more the remit of tablecmds.c and doesn't have much to do
with the basic tuple descriptor interfaces in tupdesc.c.  This is also
supported by observing the header includes we can remove in tupdesc.c.
By moving it over, we can also (in the future) make
BuildDescForRelation() use more internals of tablecmds.c that are not
sensible to be exposed in tupdesc.c.
---
 src/backend/access/common/tupdesc.c | 109 +---------------------------
 src/backend/commands/tablecmds.c    | 102 ++++++++++++++++++++++++++
 src/include/access/tupdesc.h        |   2 -
 src/include/commands/tablecmds.h    |   2 +
 4 files changed, 105 insertions(+), 110 deletions(-)

diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index c2e7b14c31..d119cfafb5 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -25,9 +25,6 @@
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/hashfn.h"
-#include "miscadmin.h"
-#include "parser/parse_type.h"
-#include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/datum.h"
 #include "utils/resowner_private.h"
@@ -778,109 +775,6 @@ TupleDescInitEntryCollation(TupleDesc desc,
 	TupleDescAttr(desc, attributeNumber - 1)->attcollation = collationid;
 }
 
-
-/*
- * BuildDescForRelation
- *
- * Given a list of ColumnDef nodes, build a TupleDesc.
- *
- * Note: tdtypeid will need to be filled in later on.
- */
-TupleDesc
-BuildDescForRelation(const List *columns)
-{
-	int			natts;
-	AttrNumber	attnum;
-	ListCell   *l;
-	TupleDesc	desc;
-	bool		has_not_null;
-	char	   *attname;
-	Oid			atttypid;
-	int32		atttypmod;
-	Oid			attcollation;
-	int			attdim;
-
-	/*
-	 * allocate a new tuple descriptor
-	 */
-	natts = list_length(columns);
-	desc = CreateTemplateTupleDesc(natts);
-	has_not_null = false;
-
-	attnum = 0;
-
-	foreach(l, columns)
-	{
-		ColumnDef  *entry = lfirst(l);
-		AclResult	aclresult;
-		Form_pg_attribute att;
-
-		/*
-		 * for each entry in the list, get the name and type information from
-		 * the list and have TupleDescInitEntry fill in the attribute
-		 * information we need.
-		 */
-		attnum++;
-
-		attname = entry->colname;
-		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
-
-		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
-		if (aclresult != ACLCHECK_OK)
-			aclcheck_error_type(aclresult, atttypid);
-
-		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
-		attdim = list_length(entry->typeName->arrayBounds);
-		if (attdim > PG_INT16_MAX)
-			ereport(ERROR,
-					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-					errmsg("too many array dimensions"));
-
-		if (entry->typeName->setof)
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
-					 errmsg("column \"%s\" cannot be declared SETOF",
-							attname)));
-
-		TupleDescInitEntry(desc, attnum, attname,
-						   atttypid, atttypmod, attdim);
-		att = TupleDescAttr(desc, attnum - 1);
-
-		/* Override TupleDescInitEntry's settings as requested */
-		TupleDescInitEntryCollation(desc, attnum, attcollation);
-		if (entry->storage)
-			att->attstorage = entry->storage;
-
-		/* Fill in additional stuff not handled by TupleDescInitEntry */
-		att->attnotnull = entry->is_not_null;
-		has_not_null |= entry->is_not_null;
-		att->attislocal = entry->is_local;
-		att->attinhcount = entry->inhcount;
-		att->attidentity = entry->identity;
-		att->attgenerated = entry->generated;
-	}
-
-	if (has_not_null)
-	{
-		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
-
-		constr->has_not_null = true;
-		constr->has_generated_stored = false;
-		constr->defval = NULL;
-		constr->missing = NULL;
-		constr->num_defval = 0;
-		constr->check = NULL;
-		constr->num_check = 0;
-		desc->constr = constr;
-	}
-	else
-	{
-		desc->constr = NULL;
-	}
-
-	return desc;
-}
-
 /*
  * BuildDescFromLists
  *
@@ -889,8 +783,7 @@ BuildDescForRelation(const List *columns)
  *
  * No constraints are generated.
  *
- * This is essentially a cut-down version of BuildDescForRelation for use
- * with functions returning RECORD.
+ * This is for use with functions returning RECORD.
  */
 TupleDesc
 BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 60ede984e0..7bd73eb379 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -1277,6 +1277,108 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	return address;
 }
 
+/*
+ * BuildDescForRelation
+ *
+ * Given a list of ColumnDef nodes, build a TupleDesc.
+ *
+ * Note: tdtypeid will need to be filled in later on.
+ */
+TupleDesc
+BuildDescForRelation(const List *columns)
+{
+	int			natts;
+	AttrNumber	attnum;
+	ListCell   *l;
+	TupleDesc	desc;
+	bool		has_not_null;
+	char	   *attname;
+	Oid			atttypid;
+	int32		atttypmod;
+	Oid			attcollation;
+	int			attdim;
+
+	/*
+	 * allocate a new tuple descriptor
+	 */
+	natts = list_length(columns);
+	desc = CreateTemplateTupleDesc(natts);
+	has_not_null = false;
+
+	attnum = 0;
+
+	foreach(l, columns)
+	{
+		ColumnDef  *entry = lfirst(l);
+		AclResult	aclresult;
+		Form_pg_attribute att;
+
+		/*
+		 * for each entry in the list, get the name and type information from
+		 * the list and have TupleDescInitEntry fill in the attribute
+		 * information we need.
+		 */
+		attnum++;
+
+		attname = entry->colname;
+		typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);
+
+		aclresult = object_aclcheck(TypeRelationId, atttypid, GetUserId(), ACL_USAGE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error_type(aclresult, atttypid);
+
+		attcollation = GetColumnDefCollation(NULL, entry, atttypid);
+		attdim = list_length(entry->typeName->arrayBounds);
+		if (attdim > PG_INT16_MAX)
+			ereport(ERROR,
+					errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+					errmsg("too many array dimensions"));
+
+		if (entry->typeName->setof)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("column \"%s\" cannot be declared SETOF",
+							attname)));
+
+		TupleDescInitEntry(desc, attnum, attname,
+						   atttypid, atttypmod, attdim);
+		att = TupleDescAttr(desc, attnum - 1);
+
+		/* Override TupleDescInitEntry's settings as requested */
+		TupleDescInitEntryCollation(desc, attnum, attcollation);
+		if (entry->storage)
+			att->attstorage = entry->storage;
+
+		/* Fill in additional stuff not handled by TupleDescInitEntry */
+		att->attnotnull = entry->is_not_null;
+		has_not_null |= entry->is_not_null;
+		att->attislocal = entry->is_local;
+		att->attinhcount = entry->inhcount;
+		att->attidentity = entry->identity;
+		att->attgenerated = entry->generated;
+	}
+
+	if (has_not_null)
+	{
+		TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));
+
+		constr->has_not_null = true;
+		constr->has_generated_stored = false;
+		constr->defval = NULL;
+		constr->missing = NULL;
+		constr->num_defval = 0;
+		constr->check = NULL;
+		constr->num_check = 0;
+		desc->constr = constr;
+	}
+	else
+	{
+		desc->constr = NULL;
+	}
+
+	return desc;
+}
+
 /*
  * Emit the right error or warning message for a "DROP" command issued on a
  * non-existent relation
diff --git a/src/include/access/tupdesc.h b/src/include/access/tupdesc.h
index ffd2874ee3..d833d5f2e1 100644
--- a/src/include/access/tupdesc.h
+++ b/src/include/access/tupdesc.h
@@ -147,8 +147,6 @@ extern void TupleDescInitEntryCollation(TupleDesc desc,
 										AttrNumber attributeNumber,
 										Oid collationid);
 
-extern TupleDesc BuildDescForRelation(const List *columns);
-
 extern TupleDesc BuildDescFromLists(const List *names, const List *types, const List *typmods, const List *collations);
 
 extern Node *TupleDescGetDefault(TupleDesc tupdesc, AttrNumber attnum);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index 16b6126669..a9c6825601 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -27,6 +27,8 @@ struct AlterTableUtilityContext;	/* avoid including tcop/utility.h here */
 extern ObjectAddress DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 									ObjectAddress *typaddress, const char *queryString);
 
+extern TupleDesc BuildDescForRelation(const List *columns);
+
 extern void RemoveRelations(DropStmt *drop);
 
 extern Oid	AlterTableLookupRelation(AlterTableStmt *stmt, LOCKMODE lockmode);
-- 
2.42.0

From 65d2d76d52b049b2e13a16018291225d844cefe0 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 7/9] Push attcompression and attstorage handling into
 BuildDescForRelation()

This was previously handled by the callers but it can be moved into a
common place.
---
 src/backend/commands/tablecmds.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 7bd73eb379..8820738d91 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -940,10 +940,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			attr->atthasdef = true;
 		}
-
-		attr->attcompression = GetAttributeCompression(attr->atttypid, colDef->compression);
-		if (colDef->storage_name)
-			attr->attstorage = GetAttributeStorage(attr->atttypid, colDef->storage_name);
 	}
 
 	/*
@@ -1346,8 +1342,6 @@ BuildDescForRelation(const List *columns)
 
 		/* Override TupleDescInitEntry's settings as requested */
 		TupleDescInitEntryCollation(desc, attnum, attcollation);
-		if (entry->storage)
-			att->attstorage = entry->storage;
 
 		/* Fill in additional stuff not handled by TupleDescInitEntry */
 		att->attnotnull = entry->is_not_null;
@@ -1356,6 +1350,11 @@ BuildDescForRelation(const List *columns)
 		att->attinhcount = entry->inhcount;
 		att->attidentity = entry->identity;
 		att->attgenerated = entry->generated;
+		att->attcompression = GetAttributeCompression(att->atttypid, entry->compression);
+		if (entry->storage)
+			att->attstorage = entry->storage;
+		else if (entry->storage_name)
+			att->attstorage = GetAttributeStorage(att->atttypid, entry->storage_name);
 	}
 
 	if (has_not_null)
-- 
2.42.0

From 5b8ffd08e58eda3176f6c6caf5b64c74a902cda4 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 8/9] Refactor ATExecAddColumn() to use
 BuildDescForRelation()

BuildDescForRelation() has all the knowledge for converting a
ColumnDef into pg_attribute/tuple descriptor.  ATExecAddColumn() can
make use of that, instead of duplicating all that logic.  We just pass
a one-element list of ColumnDef and we get back exactly the data
structure we need.  Note that we don't even need to touch
BuildDescForRelation() to make this work.
---
 src/backend/commands/tablecmds.c | 89 ++++++++------------------------
 1 file changed, 22 insertions(+), 67 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 8820738d91..d8d7ba904d 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6968,22 +6968,15 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	Relation	pgclass,
 				attrdesc;
 	HeapTuple	reltup;
-	FormData_pg_attribute attribute;
+	Form_pg_attribute attribute;
 	int			newattnum;
 	char		relkind;
-	HeapTuple	typeTuple;
-	Oid			typeOid;
-	int32		typmod;
-	Oid			collOid;
-	Form_pg_type tform;
 	Expr	   *defval;
 	List	   *children;
 	ListCell   *child;
 	AlterTableCmd *childcmd;
-	AclResult	aclresult;
 	ObjectAddress address;
 	TupleDesc	tupdesc;
-	FormData_pg_attribute *aattr[] = {&attribute};
 
 	/* At top level, permission check was done in ATPrepCmd, else do it */
 	if (recursing)
@@ -7105,59 +7098,21 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				 errmsg("tables can have at most %d columns",
 						MaxHeapAttributeNumber)));
 
-	typeTuple = typenameType(NULL, colDef->typeName, &typmod);
-	tform = (Form_pg_type) GETSTRUCT(typeTuple);
-	typeOid = tform->oid;
+	/*
+	 * Construct new attribute's pg_attribute entry.
+	 */
+	tupdesc = BuildDescForRelation(list_make1(colDef));
 
-	aclresult = object_aclcheck(TypeRelationId, typeOid, GetUserId(), ACL_USAGE);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error_type(aclresult, typeOid);
+	attribute = TupleDescAttr(tupdesc, 0);
 
-	collOid = GetColumnDefCollation(NULL, colDef, typeOid);
+	/* Fix up attribute number */
+	attribute->attnum = newattnum;
 
 	/* make sure datatype is legal for a column */
-	CheckAttributeType(colDef->colname, typeOid, collOid,
+	CheckAttributeType(NameStr(attribute->attname), attribute->atttypid, attribute->attcollation,
 					   list_make1_oid(rel->rd_rel->reltype),
 					   0);
 
-	/*
-	 * Construct new attribute's pg_attribute entry.  (Variable-length fields
-	 * are handled by InsertPgAttributeTuples().)
-	 */
-	attribute.attrelid = myrelid;
-	namestrcpy(&(attribute.attname), colDef->colname);
-	attribute.atttypid = typeOid;
-	attribute.attstattarget = -1;
-	attribute.attlen = tform->typlen;
-	attribute.attnum = newattnum;
-	if (list_length(colDef->typeName->arrayBounds) > PG_INT16_MAX)
-		ereport(ERROR,
-				errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-				errmsg("too many array dimensions"));
-	attribute.attndims = list_length(colDef->typeName->arrayBounds);
-	attribute.atttypmod = typmod;
-	attribute.attbyval = tform->typbyval;
-	attribute.attalign = tform->typalign;
-	if (colDef->storage_name)
-		attribute.attstorage = GetAttributeStorage(typeOid, colDef->storage_name);
-	else
-		attribute.attstorage = tform->typstorage;
-	attribute.attcompression = GetAttributeCompression(typeOid,
-													   colDef->compression);
-	attribute.attnotnull = colDef->is_not_null;
-	attribute.atthasdef = false;
-	attribute.atthasmissing = false;
-	attribute.attidentity = colDef->identity;
-	attribute.attgenerated = colDef->generated;
-	attribute.attisdropped = false;
-	attribute.attislocal = colDef->is_local;
-	attribute.attinhcount = colDef->inhcount;
-	attribute.attcollation = collOid;
-
-	ReleaseSysCache(typeTuple);
-
-	tupdesc = CreateTupleDesc(lengthof(aattr), (FormData_pg_attribute **) &aattr);
-
 	InsertPgAttributeTuples(attrdesc, tupdesc, myrelid, NULL, NULL);
 
 	table_close(attrdesc, RowExclusiveLock);
@@ -7187,7 +7142,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		RawColumnDefault *rawEnt;
 
 		rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
-		rawEnt->attnum = attribute.attnum;
+		rawEnt->attnum = attribute->attnum;
 		rawEnt->raw_default = copyObject(colDef->raw_default);
 
 		/*
@@ -7261,7 +7216,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NextValueExpr *nve = makeNode(NextValueExpr);
 
 			nve->seqid = RangeVarGetRelid(colDef->identitySequence, NoLock, false);
-			nve->typeId = typeOid;
+			nve->typeId = attribute->atttypid;
 
 			defval = (Expr *) nve;
 
@@ -7269,23 +7224,23 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 		}
 		else
-			defval = (Expr *) build_column_default(rel, attribute.attnum);
+			defval = (Expr *) build_column_default(rel, attribute->attnum);
 
-		if (!defval && DomainHasConstraints(typeOid))
+		if (!defval && DomainHasConstraints(attribute->atttypid))
 		{
 			Oid			baseTypeId;
 			int32		baseTypeMod;
 			Oid			baseTypeColl;
 
-			baseTypeMod = typmod;
-			baseTypeId = getBaseTypeAndTypmod(typeOid, &baseTypeMod);
+			baseTypeMod = attribute->atttypmod;
+			baseTypeId = getBaseTypeAndTypmod(attribute->atttypid, &baseTypeMod);
 			baseTypeColl = get_typcollation(baseTypeId);
 			defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod, baseTypeColl);
 			defval = (Expr *) coerce_to_target_type(NULL,
 													(Node *) defval,
 													baseTypeId,
-													typeOid,
-													typmod,
+													attribute->atttypid,
+													attribute->atttypmod,
 													COERCION_ASSIGNMENT,
 													COERCE_IMPLICIT_CAST,
 													-1);
@@ -7298,17 +7253,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NewColumnValue *newval;
 
 			newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
-			newval->attnum = attribute.attnum;
+			newval->attnum = attribute->attnum;
 			newval->expr = expression_planner(defval);
 			newval->is_generated = (colDef->generated != '\0');
 
 			tab->newvals = lappend(tab->newvals, newval);
 		}
 
-		if (DomainHasConstraints(typeOid))
+		if (DomainHasConstraints(attribute->atttypid))
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
-		if (!TupleDescAttr(rel->rd_att, attribute.attnum - 1)->atthasmissing)
+		if (!TupleDescAttr(rel->rd_att, attribute->attnum - 1)->atthasmissing)
 		{
 			/*
 			 * If the new column is NOT NULL, and there is no missing value,
@@ -7321,8 +7276,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Add needed dependency entries for the new column.
 	 */
-	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
-	add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
+	add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid);
+	add_column_collation_dependency(myrelid, newattnum, attribute->attcollation);
 
 	/*
 	 * Propagate to children as appropriate.  Unlike most other ALTER
-- 
2.42.0

From a1000260efb736f2c1e6c161a1475676228a8be8 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 12 Jul 2023 16:12:35 +0200
Subject: [PATCH v3 9/9] MergeAttributes: convert pg_attribute back to
 ColumnDef before comparing

MergeAttributes() has a loop to merge multiple inheritance parents
into a column column definition.  The merged-so-far definition is
stored in a ColumnDef node.  If we have to merge columns from multiple
inheritance parents (if the name matches), then we have to check
whether various column properties (type, collation, etc.) match.  The
current code extracts the pg_attribute value of the
currently-considered inheritance parent and compares it against the
merge-so-far ColumnDef value.  If the currently considered column
doesn't match any previously inherited column, we make a new ColumnDef
node from the pg_attribute information and add it to the column list.

This patch rearranges this so that we create the ColumnDef node first
in either case.  Then the code that checks the column properties for
compatibility compares ColumnDef against ColumnDef (instead of
ColumnDef against pg_attribute).  This matches the code more symmetric
and easier to follow.  Also, later in MergeAttributes(), there is a
similar but separate loop that merges the new local column definition
with the combination of the inheritance parents established in the
first loop.  That comparison is already ColumnDef-vs-ColumnDef.  With
this change, but of these can use similar looking logic.  (A future
project might be to extract these two sets of code into a common
routine that encodes all the knowledge of whether two column
definitions are compatible.  But this isn't currently straightforward
because we want to give different error messages in the two cases.)
Furthermore, by avoiding the use of Form_pg_attribute here, we make it
easier to make changes in the pg_attribute layout without having to
worry about the local needs of tablecmds.c.

Because MergeAttributes() is hugely long, it's sometimes hard to know
where in the function you are currently looking.  To help with that, I
also renamed some variables to make it clearer where you are currently
looking.  The first look is "prev" vs. "new", the second loop is "inh"
vs. "new".
---
 src/backend/commands/tablecmds.c | 181 ++++++++++++++++---------------
 1 file changed, 94 insertions(+), 87 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d8d7ba904d..9b9b5ad5e8 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2697,7 +2697,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
-			ColumnDef  *def;
+			ColumnDef  *newdef;
+			ColumnDef  *savedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2706,14 +2707,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Create new column definition
+			 */
+			newdef = makeColumnDef(attributeName, attribute->atttypid,
+								   attribute->atttypmod, attribute->attcollation);
+			newdef->storage = attribute->attstorage;
+			newdef->generated = attribute->attgenerated;
+			if (CompressionMethodIsValid(attribute->attcompression))
+				newdef->compression =
+					pstrdup(GetCompressionMethodName(attribute->attcompression));
+
+			/*
+			 * Does it match some previously considered column from another
+			 * parent?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				Oid			defTypeId;
-				int32		deftypmod;
-				Oid			defCollId;
+				ColumnDef  *prevdef;
+				Oid			prevtypeid,
+							newtypeid;
+				int32		prevtypmod,
+							newtypmod;
+				Oid			prevcollid,
+							newcollid;
 
 				/*
 				 * Yes, try to merge the two column definitions.
@@ -2721,68 +2738,61 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				if (defTypeId != attribute->atttypid ||
-					deftypmod != attribute->atttypmod)
+				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(attribute->atttypid,
-																attribute->atttypmod))));
+									   format_type_with_typemod(prevtypeid, prevtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
-				if (defCollId != attribute->attcollation)
+				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (prevcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("inherited column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defCollId),
-									   get_collation_name(attribute->attcollation))));
+									   get_collation_name(prevcollid),
+									   get_collation_name(newcollid))));
 
 				/*
 				 * Copy/check storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = attribute->attstorage;
-				else if (def->storage != attribute->attstorage)
+				if (prevdef->storage == 0)
+					prevdef->storage = newdef->storage;
+				else if (prevdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
-									   storage_name(attribute->attstorage))));
+									   storage_name(prevdef->storage),
+									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy/check compression parameter
 				 */
-				if (CompressionMethodIsValid(attribute->attcompression))
-				{
-					const char *compression =
-						GetCompressionMethodName(attribute->attcompression);
-
-					if (def->compression == NULL)
-						def->compression = pstrdup(compression);
-					else if (strcmp(def->compression, compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
-				}
+				if (prevdef->compression == NULL)
+					prevdef->compression = newdef->compression;
+				else if (strcmp(prevdef->compression, newdef->compression) != 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has a compression method conflict",
+									attributeName),
+							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
 
 				/*
 				 * In regular inheritance, columns in the parent's primary key
@@ -2816,12 +2826,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
+					newdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
 				 */
-				if (def->generated != attribute->attgenerated)
+				if (prevdef->generated != newdef->generated)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a generation conflict",
@@ -2831,34 +2841,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * Default and other constraints are handled below
 				 */
 
-				def->inhcount++;
-				if (def->inhcount < 0)
+				prevdef->inhcount++;
+				if (prevdef->inhcount < 0)
 					ereport(ERROR,
 							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 							errmsg("too many inheritance parents"));
 
 				newattmap->attnums[parent_attno - 1] = exist_attno;
+
+				/* remember for default processing below */
+				savedef = prevdef;
 			}
 			else
 			{
 				/*
 				 * No, create a new inherited column
 				 */
-				def = makeColumnDef(attributeName, attribute->atttypid,
-									attribute->atttypmod, attribute->attcollation);
-				def->inhcount = 1;
-				def->is_local = false;
+				newdef->inhcount = 1;
+				newdef->is_local = false;
 				/* mark attnotnull if parent has it and it's not NO INHERIT */
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
-				def->storage = attribute->attstorage;
-				def->generated = attribute->attgenerated;
-				if (CompressionMethodIsValid(attribute->attcompression))
-					def->compression =
-						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inh_columns = lappend(inh_columns, def);
+					newdef->is_not_null = true;
+				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2887,6 +2893,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 					nnconstraints = lappend(nnconstraints, nn);
 				}
+
+				/* remember for default processing below */
+				savedef = newdef;
 			}
 
 			/*
@@ -2908,7 +2917,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, def);
+				cols_with_defaults = lappend(cols_with_defaults, savedef);
 			}
 		}
 
@@ -3046,17 +3055,17 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			newcol_attno++;
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Does it match some inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				ColumnDef  *def;
-				Oid			defTypeId,
-							newTypeId;
-				int32		deftypmod,
+				ColumnDef  *inhdef;
+				Oid			inhtypeid,
+							newtypeid;
+				int32		inhtypmod,
 							newtypmod;
-				Oid			defcollid,
+				Oid			inhcollid,
 							newcollid;
 
 				/*
@@ -3076,77 +3085,75 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
-				if (defTypeId != newTypeId || deftypmod != newtypmod)
+				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(newTypeId,
-																newtypmod))));
+									   format_type_with_typemod(inhtypeid, inhtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
-				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
-				if (defcollid != newcollid)
+				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (inhcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defcollid),
+									   get_collation_name(inhcollid),
 									   get_collation_name(newcollid))));
 
 				/*
 				 * Identity is never inherited.  The new column can have an
 				 * identity definition, so we always just take that one.
 				 */
-				def->identity = newdef->identity;
+				inhdef->identity = newdef->identity;
 
 				/*
 				 * Copy storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = newdef->storage;
-				else if (newdef->storage != 0 && def->storage != newdef->storage)
+				if (inhdef->storage == 0)
+					inhdef->storage = newdef->storage;
+				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
+									   storage_name(inhdef->storage),
 									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy compression parameter
 				 */
-				if (def->compression == NULL)
-					def->compression = newdef->compression;
+				if (inhdef->compression == NULL)
+					inhdef->compression = newdef->compression;
 				else if (newdef->compression != NULL)
 				{
-					if (strcmp(def->compression, newdef->compression) != 0)
+					if (strcmp(inhdef->compression, newdef->compression) != 0)
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
 				}
 
 				/*
 				 * Merge of not-null constraints = OR 'em together
 				 */
-				def->is_not_null |= newdef->is_not_null;
+				inhdef->is_not_null |= newdef->is_not_null;
 
 				/*
 				 * Check for conflicts related to generated columns.
@@ -3163,18 +3170,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * it results in being able to override the generation
 				 * expression via UPDATEs through the parent.)
 				 */
-				if (def->generated)
+				if (inhdef->generated)
 				{
 					if (newdef->raw_default && !newdef->generated)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										def->colname)));
+										inhdef->colname)));
 					if (newdef->identity)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										def->colname)));
+										inhdef->colname)));
 				}
 				else
 				{
@@ -3182,7 +3189,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("child column \"%s\" specifies generation expression",
-										def->colname),
+										inhdef->colname),
 								 errhint("A child table column cannot be generated unless its parent column is.")));
 				}
 
@@ -3191,12 +3198,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 */
 				if (newdef->raw_default != NULL)
 				{
-					def->raw_default = newdef->raw_default;
-					def->cooked_default = newdef->cooked_default;
+					inhdef->raw_default = newdef->raw_default;
+					inhdef->cooked_default = newdef->cooked_default;
 				}
 
 				/* Mark the column as locally defined */
-				def->is_local = true;
+				inhdef->is_local = true;
 			}
 			else
 			{
-- 
2.42.0

From 42615f4c523920c7ae916ba0b1819cc6a5e622b1 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 5 Oct 2023 16:17:16 +0200
Subject: [PATCH v4 1/2] Refactor ATExecAddColumn() to use
 BuildDescForRelation()

BuildDescForRelation() has all the knowledge for converting a
ColumnDef into pg_attribute/tuple descriptor.  ATExecAddColumn() can
make use of that, instead of duplicating all that logic.  We just pass
a one-element list of ColumnDef and we get back exactly the data
structure we need.  Note that we don't even need to touch
BuildDescForRelation() to make this work.

Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org
---
 src/backend/commands/tablecmds.c | 89 ++++++++------------------------
 1 file changed, 22 insertions(+), 67 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 6b0a20010e..875cfeaa5a 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6965,22 +6965,15 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	Relation	pgclass,
 				attrdesc;
 	HeapTuple	reltup;
-	FormData_pg_attribute attribute;
+	Form_pg_attribute attribute;
 	int			newattnum;
 	char		relkind;
-	HeapTuple	typeTuple;
-	Oid			typeOid;
-	int32		typmod;
-	Oid			collOid;
-	Form_pg_type tform;
 	Expr	   *defval;
 	List	   *children;
 	ListCell   *child;
 	AlterTableCmd *childcmd;
-	AclResult	aclresult;
 	ObjectAddress address;
 	TupleDesc	tupdesc;
-	FormData_pg_attribute *aattr[] = {&attribute};
 
 	/* At top level, permission check was done in ATPrepCmd, else do it */
 	if (recursing)
@@ -7102,59 +7095,21 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				 errmsg("tables can have at most %d columns",
 						MaxHeapAttributeNumber)));
 
-	typeTuple = typenameType(NULL, colDef->typeName, &typmod);
-	tform = (Form_pg_type) GETSTRUCT(typeTuple);
-	typeOid = tform->oid;
+	/*
+	 * Construct new attribute's pg_attribute entry.
+	 */
+	tupdesc = BuildDescForRelation(list_make1(colDef));
 
-	aclresult = object_aclcheck(TypeRelationId, typeOid, GetUserId(), ACL_USAGE);
-	if (aclresult != ACLCHECK_OK)
-		aclcheck_error_type(aclresult, typeOid);
+	attribute = TupleDescAttr(tupdesc, 0);
 
-	collOid = GetColumnDefCollation(NULL, colDef, typeOid);
+	/* Fix up attribute number */
+	attribute->attnum = newattnum;
 
 	/* make sure datatype is legal for a column */
-	CheckAttributeType(colDef->colname, typeOid, collOid,
+	CheckAttributeType(NameStr(attribute->attname), attribute->atttypid, attribute->attcollation,
 					   list_make1_oid(rel->rd_rel->reltype),
 					   0);
 
-	/*
-	 * Construct new attribute's pg_attribute entry.  (Variable-length fields
-	 * are handled by InsertPgAttributeTuples().)
-	 */
-	attribute.attrelid = myrelid;
-	namestrcpy(&(attribute.attname), colDef->colname);
-	attribute.atttypid = typeOid;
-	attribute.attstattarget = -1;
-	attribute.attlen = tform->typlen;
-	attribute.attnum = newattnum;
-	if (list_length(colDef->typeName->arrayBounds) > PG_INT16_MAX)
-		ereport(ERROR,
-				errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-				errmsg("too many array dimensions"));
-	attribute.attndims = list_length(colDef->typeName->arrayBounds);
-	attribute.atttypmod = typmod;
-	attribute.attbyval = tform->typbyval;
-	attribute.attalign = tform->typalign;
-	if (colDef->storage_name)
-		attribute.attstorage = GetAttributeStorage(typeOid, colDef->storage_name);
-	else
-		attribute.attstorage = tform->typstorage;
-	attribute.attcompression = GetAttributeCompression(typeOid,
-													   colDef->compression);
-	attribute.attnotnull = colDef->is_not_null;
-	attribute.atthasdef = false;
-	attribute.atthasmissing = false;
-	attribute.attidentity = colDef->identity;
-	attribute.attgenerated = colDef->generated;
-	attribute.attisdropped = false;
-	attribute.attislocal = colDef->is_local;
-	attribute.attinhcount = colDef->inhcount;
-	attribute.attcollation = collOid;
-
-	ReleaseSysCache(typeTuple);
-
-	tupdesc = CreateTupleDesc(lengthof(aattr), (FormData_pg_attribute **) &aattr);
-
 	InsertPgAttributeTuples(attrdesc, tupdesc, myrelid, NULL, NULL);
 
 	table_close(attrdesc, RowExclusiveLock);
@@ -7184,7 +7139,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		RawColumnDefault *rawEnt;
 
 		rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
-		rawEnt->attnum = attribute.attnum;
+		rawEnt->attnum = attribute->attnum;
 		rawEnt->raw_default = copyObject(colDef->raw_default);
 
 		/*
@@ -7258,7 +7213,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NextValueExpr *nve = makeNode(NextValueExpr);
 
 			nve->seqid = RangeVarGetRelid(colDef->identitySequence, NoLock, false);
-			nve->typeId = typeOid;
+			nve->typeId = attribute->atttypid;
 
 			defval = (Expr *) nve;
 
@@ -7266,23 +7221,23 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 		}
 		else
-			defval = (Expr *) build_column_default(rel, attribute.attnum);
+			defval = (Expr *) build_column_default(rel, attribute->attnum);
 
-		if (!defval && DomainHasConstraints(typeOid))
+		if (!defval && DomainHasConstraints(attribute->atttypid))
 		{
 			Oid			baseTypeId;
 			int32		baseTypeMod;
 			Oid			baseTypeColl;
 
-			baseTypeMod = typmod;
-			baseTypeId = getBaseTypeAndTypmod(typeOid, &baseTypeMod);
+			baseTypeMod = attribute->atttypmod;
+			baseTypeId = getBaseTypeAndTypmod(attribute->atttypid, &baseTypeMod);
 			baseTypeColl = get_typcollation(baseTypeId);
 			defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod, baseTypeColl);
 			defval = (Expr *) coerce_to_target_type(NULL,
 													(Node *) defval,
 													baseTypeId,
-													typeOid,
-													typmod,
+													attribute->atttypid,
+													attribute->atttypmod,
 													COERCION_ASSIGNMENT,
 													COERCE_IMPLICIT_CAST,
 													-1);
@@ -7295,17 +7250,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 			NewColumnValue *newval;
 
 			newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
-			newval->attnum = attribute.attnum;
+			newval->attnum = attribute->attnum;
 			newval->expr = expression_planner(defval);
 			newval->is_generated = (colDef->generated != '\0');
 
 			tab->newvals = lappend(tab->newvals, newval);
 		}
 
-		if (DomainHasConstraints(typeOid))
+		if (DomainHasConstraints(attribute->atttypid))
 			tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
-		if (!TupleDescAttr(rel->rd_att, attribute.attnum - 1)->atthasmissing)
+		if (!TupleDescAttr(rel->rd_att, attribute->attnum - 1)->atthasmissing)
 		{
 			/*
 			 * If the new column is NOT NULL, and there is no missing value,
@@ -7318,8 +7273,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	/*
 	 * Add needed dependency entries for the new column.
 	 */
-	add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
-	add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
+	add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid);
+	add_column_collation_dependency(myrelid, newattnum, attribute->attcollation);
 
 	/*
 	 * Propagate to children as appropriate.  Unlike most other ALTER

base-commit: 7636725b922c8cd68f21d040f3542d3bce9c68a4
-- 
2.43.0

From 8fe0e8157d932c33ab06e0eccdfa0e2634e27935 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Thu, 5 Oct 2023 16:17:16 +0200
Subject: [PATCH v4 2/2] MergeAttributes: convert pg_attribute back to
 ColumnDef before comparing

MergeAttributes() has a loop to merge multiple inheritance parents
into a column column definition.  The merged-so-far definition is
stored in a ColumnDef node.  If we have to merge columns from multiple
inheritance parents (if the name matches), then we have to check
whether various column properties (type, collation, etc.) match.  The
current code extracts the pg_attribute value of the
currently-considered inheritance parent and compares it against the
merge-so-far ColumnDef value.  If the currently considered column
doesn't match any previously inherited column, we make a new ColumnDef
node from the pg_attribute information and add it to the column list.

This patch rearranges this so that we create the ColumnDef node first
in either case.  Then the code that checks the column properties for
compatibility compares ColumnDef against ColumnDef (instead of
ColumnDef against pg_attribute).  This matches the code more symmetric
and easier to follow.  Also, later in MergeAttributes(), there is a
similar but separate loop that merges the new local column definition
with the combination of the inheritance parents established in the
first loop.  That comparison is already ColumnDef-vs-ColumnDef.  With
this change, but of these can use similar looking logic.  (A future
project might be to extract these two sets of code into a common
routine that encodes all the knowledge of whether two column
definitions are compatible.  But this isn't currently straightforward
because we want to give different error messages in the two cases.)
Furthermore, by avoiding the use of Form_pg_attribute here, we make it
easier to make changes in the pg_attribute layout without having to
worry about the local needs of tablecmds.c.

Because MergeAttributes() is hugely long, it's sometimes hard to know
where in the function you are currently looking.  To help with that, I
also renamed some variables to make it clearer where you are currently
looking.  The first look is "prev" vs. "new", the second loop is "inh"
vs. "new".

Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org
---
 src/backend/commands/tablecmds.c | 181 ++++++++++++++++---------------
 1 file changed, 94 insertions(+), 87 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 875cfeaa5a..2cd8aefb35 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2694,7 +2694,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
-			ColumnDef  *def;
+			ColumnDef  *newdef;
+			ColumnDef  *savedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2703,14 +2704,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Create new column definition
+			 */
+			newdef = makeColumnDef(attributeName, attribute->atttypid,
+								   attribute->atttypmod, attribute->attcollation);
+			newdef->storage = attribute->attstorage;
+			newdef->generated = attribute->attgenerated;
+			if (CompressionMethodIsValid(attribute->attcompression))
+				newdef->compression =
+					pstrdup(GetCompressionMethodName(attribute->attcompression));
+
+			/*
+			 * Does it match some previously considered column from another
+			 * parent?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				Oid			defTypeId;
-				int32		deftypmod;
-				Oid			defCollId;
+				ColumnDef  *prevdef;
+				Oid			prevtypeid,
+							newtypeid;
+				int32		prevtypmod,
+							newtypmod;
+				Oid			prevcollid,
+							newcollid;
 
 				/*
 				 * Yes, try to merge the two column definitions.
@@ -2718,68 +2735,61 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				if (defTypeId != attribute->atttypid ||
-					deftypmod != attribute->atttypmod)
+				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(attribute->atttypid,
-																attribute->atttypmod))));
+									   format_type_with_typemod(prevtypeid, prevtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
-				if (defCollId != attribute->attcollation)
+				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (prevcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("inherited column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defCollId),
-									   get_collation_name(attribute->attcollation))));
+									   get_collation_name(prevcollid),
+									   get_collation_name(newcollid))));
 
 				/*
 				 * Copy/check storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = attribute->attstorage;
-				else if (def->storage != attribute->attstorage)
+				if (prevdef->storage == 0)
+					prevdef->storage = newdef->storage;
+				else if (prevdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
-									   storage_name(attribute->attstorage))));
+									   storage_name(prevdef->storage),
+									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy/check compression parameter
 				 */
-				if (CompressionMethodIsValid(attribute->attcompression))
-				{
-					const char *compression =
-						GetCompressionMethodName(attribute->attcompression);
-
-					if (def->compression == NULL)
-						def->compression = pstrdup(compression);
-					else if (strcmp(def->compression, compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
-				}
+				if (prevdef->compression == NULL)
+					prevdef->compression = newdef->compression;
+				else if (strcmp(prevdef->compression, newdef->compression) != 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has a compression method conflict",
+									attributeName),
+							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
 
 				/*
 				 * In regular inheritance, columns in the parent's primary key
@@ -2813,12 +2823,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
+					newdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
 				 */
-				if (def->generated != attribute->attgenerated)
+				if (prevdef->generated != newdef->generated)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a generation conflict",
@@ -2828,34 +2838,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * Default and other constraints are handled below
 				 */
 
-				def->inhcount++;
-				if (def->inhcount < 0)
+				prevdef->inhcount++;
+				if (prevdef->inhcount < 0)
 					ereport(ERROR,
 							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 							errmsg("too many inheritance parents"));
 
 				newattmap->attnums[parent_attno - 1] = exist_attno;
+
+				/* remember for default processing below */
+				savedef = prevdef;
 			}
 			else
 			{
 				/*
 				 * No, create a new inherited column
 				 */
-				def = makeColumnDef(attributeName, attribute->atttypid,
-									attribute->atttypmod, attribute->attcollation);
-				def->inhcount = 1;
-				def->is_local = false;
+				newdef->inhcount = 1;
+				newdef->is_local = false;
 				/* mark attnotnull if parent has it and it's not NO INHERIT */
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
-				def->storage = attribute->attstorage;
-				def->generated = attribute->attgenerated;
-				if (CompressionMethodIsValid(attribute->attcompression))
-					def->compression =
-						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inh_columns = lappend(inh_columns, def);
+					newdef->is_not_null = true;
+				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2884,6 +2890,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 					nnconstraints = lappend(nnconstraints, nn);
 				}
+
+				/* remember for default processing below */
+				savedef = newdef;
 			}
 
 			/*
@@ -2905,7 +2914,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, def);
+				cols_with_defaults = lappend(cols_with_defaults, savedef);
 			}
 		}
 
@@ -3043,17 +3052,17 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			newcol_attno++;
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Does it match some inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				ColumnDef  *def;
-				Oid			defTypeId,
-							newTypeId;
-				int32		deftypmod,
+				ColumnDef  *inhdef;
+				Oid			inhtypeid,
+							newtypeid;
+				int32		inhtypmod,
 							newtypmod;
-				Oid			defcollid,
+				Oid			inhcollid,
 							newcollid;
 
 				/*
@@ -3073,77 +3082,75 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
-				if (defTypeId != newTypeId || deftypmod != newtypmod)
+				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(newTypeId,
-																newtypmod))));
+									   format_type_with_typemod(inhtypeid, inhtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
-				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
-				if (defcollid != newcollid)
+				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (inhcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defcollid),
+									   get_collation_name(inhcollid),
 									   get_collation_name(newcollid))));
 
 				/*
 				 * Identity is never inherited.  The new column can have an
 				 * identity definition, so we always just take that one.
 				 */
-				def->identity = newdef->identity;
+				inhdef->identity = newdef->identity;
 
 				/*
 				 * Copy storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = newdef->storage;
-				else if (newdef->storage != 0 && def->storage != newdef->storage)
+				if (inhdef->storage == 0)
+					inhdef->storage = newdef->storage;
+				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
+									   storage_name(inhdef->storage),
 									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy compression parameter
 				 */
-				if (def->compression == NULL)
-					def->compression = newdef->compression;
+				if (inhdef->compression == NULL)
+					inhdef->compression = newdef->compression;
 				else if (newdef->compression != NULL)
 				{
-					if (strcmp(def->compression, newdef->compression) != 0)
+					if (strcmp(inhdef->compression, newdef->compression) != 0)
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
 				}
 
 				/*
 				 * Merge of not-null constraints = OR 'em together
 				 */
-				def->is_not_null |= newdef->is_not_null;
+				inhdef->is_not_null |= newdef->is_not_null;
 
 				/*
 				 * Check for conflicts related to generated columns.
@@ -3160,18 +3167,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * it results in being able to override the generation
 				 * expression via UPDATEs through the parent.)
 				 */
-				if (def->generated)
+				if (inhdef->generated)
 				{
 					if (newdef->raw_default && !newdef->generated)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										def->colname)));
+										inhdef->colname)));
 					if (newdef->identity)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										def->colname)));
+										inhdef->colname)));
 				}
 				else
 				{
@@ -3179,7 +3186,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("child column \"%s\" specifies generation expression",
-										def->colname),
+										inhdef->colname),
 								 errhint("A child table column cannot be generated unless its parent column is.")));
 				}
 
@@ -3188,12 +3195,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 */
 				if (newdef->raw_default != NULL)
 				{
-					def->raw_default = newdef->raw_default;
-					def->cooked_default = newdef->cooked_default;
+					inhdef->raw_default = newdef->raw_default;
+					inhdef->cooked_default = newdef->cooked_default;
 				}
 
 				/* Mark the column as locally defined */
-				def->is_local = true;
+				inhdef->is_local = true;
 			}
 			else
 			{
-- 
2.43.0

From c4c4462fa58c73fc383c4935c8d2753b7a0b4c9d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 22 Jan 2024 13:23:43 +0100
Subject: [PATCH v5] MergeAttributes: convert pg_attribute back to ColumnDef
 before comparing

MergeAttributes() has a loop to merge multiple inheritance parents
into a column column definition.  The merged-so-far definition is
stored in a ColumnDef node.  If we have to merge columns from multiple
inheritance parents (if the name matches), then we have to check
whether various column properties (type, collation, etc.) match.  The
current code extracts the pg_attribute value of the
currently-considered inheritance parent and compares it against the
merged-so-far ColumnDef value.  If the currently considered column
doesn't match any previously inherited column, we make a new ColumnDef
node from the pg_attribute information and add it to the column list.

This patch rearranges this so that we create the ColumnDef node first
in either case.  Then the code that checks the column properties for
compatibility compares ColumnDef against ColumnDef (instead of
ColumnDef against pg_attribute).  This makes the code more symmetric
and easier to follow.  Also, later in MergeAttributes(), there is a
similar but separate loop that merges the new local column definition
with the combination of the inheritance parents established in the
first loop.  That comparison is already ColumnDef-vs-ColumnDef.  With
this change, both of these can use similar-looking logic.  (A future
project might be to extract these two sets of code into a common
routine that encodes all the knowledge of whether two column
definitions are compatible.  But this isn't currently straightforward
because we want to give different error messages in the two cases.)
Furthermore, by avoiding the use of Form_pg_attribute here, we make it
easier to make changes in the pg_attribute layout without having to
worry about the local needs of tablecmds.c.

Because MergeAttributes() is hugely long, it's sometimes hard to know
where in the function you are currently looking.  To help with that, I
also renamed some variables to make it clearer where you are currently
looking.  The first look is "prev" vs. "new", the second loop is "inh"
vs. "new".

Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org
---
 src/backend/commands/tablecmds.c | 198 ++++++++++++++++---------------
 1 file changed, 102 insertions(+), 96 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2a56a4357c9..04e674bbdae 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2704,7 +2704,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
-			ColumnDef  *def;
+			ColumnDef  *newdef;
+			ColumnDef  *savedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2713,14 +2714,38 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Create new column definition
+			 */
+			newdef = makeColumnDef(attributeName, attribute->atttypid,
+								   attribute->atttypmod, attribute->attcollation);
+			newdef->storage = attribute->attstorage;
+			newdef->generated = attribute->attgenerated;
+			if (CompressionMethodIsValid(attribute->attcompression))
+				newdef->compression =
+					pstrdup(GetCompressionMethodName(attribute->attcompression));
+
+			/*
+			 * Regular inheritance children are independent enough not to
+			 * inherit identity columns.  But partitions are integral part
+			 * of a partitioned table and inherit identity column.
+			 */
+			if (is_partition)
+				newdef->identity = attribute->attidentity;
+
+			/*
+			 * Does it match some previously considered column from another
+			 * parent?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				Oid			defTypeId;
-				int32		deftypmod;
-				Oid			defCollId;
+				ColumnDef  *prevdef;
+				Oid			prevtypeid,
+							newtypeid;
+				int32		prevtypmod,
+							newtypmod;
+				Oid			prevcollid,
+							newcollid;
 
 				/*
 				 * Partitions have only one parent and have no column
@@ -2734,68 +2759,61 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				if (defTypeId != attribute->atttypid ||
-					deftypmod != attribute->atttypmod)
+				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(attribute->atttypid,
-																attribute->atttypmod))));
+									   format_type_with_typemod(prevtypeid, prevtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
-				if (defCollId != attribute->attcollation)
+				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (prevcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("inherited column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defCollId),
-									   get_collation_name(attribute->attcollation))));
+									   get_collation_name(prevcollid),
+									   get_collation_name(newcollid))));
 
 				/*
 				 * Copy/check storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = attribute->attstorage;
-				else if (def->storage != attribute->attstorage)
+				if (prevdef->storage == 0)
+					prevdef->storage = newdef->storage;
+				else if (prevdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
-									   storage_name(attribute->attstorage))));
+									   storage_name(prevdef->storage),
+									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy/check compression parameter
 				 */
-				if (CompressionMethodIsValid(attribute->attcompression))
-				{
-					const char *compression =
-						GetCompressionMethodName(attribute->attcompression);
-
-					if (def->compression == NULL)
-						def->compression = pstrdup(compression);
-					else if (strcmp(def->compression, compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
-				}
+				if (prevdef->compression == NULL)
+					prevdef->compression = newdef->compression;
+				else if (strcmp(prevdef->compression, newdef->compression) != 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has a compression method conflict",
+									attributeName),
+							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
 
 				/*
 				 * In regular inheritance, columns in the parent's primary key
@@ -2826,12 +2844,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
+					newdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
 				 */
-				if (def->generated != attribute->attgenerated)
+				if (prevdef->generated != newdef->generated)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a generation conflict",
@@ -2841,43 +2859,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * Default and other constraints are handled below
 				 */
 
-				def->inhcount++;
-				if (def->inhcount < 0)
+				prevdef->inhcount++;
+				if (prevdef->inhcount < 0)
 					ereport(ERROR,
 							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 							errmsg("too many inheritance parents"));
 
 				newattmap->attnums[parent_attno - 1] = exist_attno;
+
+				/* remember for default processing below */
+				savedef = prevdef;
 			}
 			else
 			{
 				/*
 				 * No, create a new inherited column
 				 */
-				def = makeColumnDef(attributeName, attribute->atttypid,
-									attribute->atttypmod, attribute->attcollation);
-				def->inhcount = 1;
-				def->is_local = false;
+				newdef->inhcount = 1;
+				newdef->is_local = false;
 				/* mark attnotnull if parent has it and it's not NO INHERIT */
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
-				def->storage = attribute->attstorage;
-				def->generated = attribute->attgenerated;
-
-				/*
-				 * Regular inheritance children are independent enough not to
-				 * inherit identity columns.  But partitions are integral part
-				 * of a partitioned table and inherit identity column.
-				 */
-				if (is_partition)
-					def->identity = attribute->attidentity;
-
-				if (CompressionMethodIsValid(attribute->attcompression))
-					def->compression =
-						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inh_columns = lappend(inh_columns, def);
+					newdef->is_not_null = true;
+				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2906,6 +2911,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 					nnconstraints = lappend(nnconstraints, nn);
 				}
+
+				/* remember for default processing below */
+				savedef = newdef;
 			}
 
 			/*
@@ -2927,7 +2935,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, def);
+				cols_with_defaults = lappend(cols_with_defaults, savedef);
 			}
 		}
 
@@ -3065,17 +3073,17 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			newcol_attno++;
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Does it match some inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				ColumnDef  *def;
-				Oid			defTypeId,
-							newTypeId;
-				int32		deftypmod,
+				ColumnDef  *inhdef;
+				Oid			inhtypeid,
+							newtypeid;
+				int32		inhtypmod,
 							newtypmod;
-				Oid			defcollid,
+				Oid			inhcollid,
 							newcollid;
 
 				/*
@@ -3095,77 +3103,75 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
-				if (defTypeId != newTypeId || deftypmod != newtypmod)
+				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(newTypeId,
-																newtypmod))));
+									   format_type_with_typemod(inhtypeid, inhtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
-				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
-				if (defcollid != newcollid)
+				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (inhcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defcollid),
+									   get_collation_name(inhcollid),
 									   get_collation_name(newcollid))));
 
 				/*
 				 * Identity is never inherited.  The new column can have an
 				 * identity definition, so we always just take that one.
 				 */
-				def->identity = newdef->identity;
+				inhdef->identity = newdef->identity;
 
 				/*
 				 * Copy storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = newdef->storage;
-				else if (newdef->storage != 0 && def->storage != newdef->storage)
+				if (inhdef->storage == 0)
+					inhdef->storage = newdef->storage;
+				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
+									   storage_name(inhdef->storage),
 									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy compression parameter
 				 */
-				if (def->compression == NULL)
-					def->compression = newdef->compression;
+				if (inhdef->compression == NULL)
+					inhdef->compression = newdef->compression;
 				else if (newdef->compression != NULL)
 				{
-					if (strcmp(def->compression, newdef->compression) != 0)
+					if (strcmp(inhdef->compression, newdef->compression) != 0)
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
 				}
 
 				/*
 				 * Merge of not-null constraints = OR 'em together
 				 */
-				def->is_not_null |= newdef->is_not_null;
+				inhdef->is_not_null |= newdef->is_not_null;
 
 				/*
 				 * Check for conflicts related to generated columns.
@@ -3182,18 +3188,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * it results in being able to override the generation
 				 * expression via UPDATEs through the parent.)
 				 */
-				if (def->generated)
+				if (inhdef->generated)
 				{
 					if (newdef->raw_default && !newdef->generated)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										def->colname)));
+										inhdef->colname)));
 					if (newdef->identity)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										def->colname)));
+										inhdef->colname)));
 				}
 				else
 				{
@@ -3201,7 +3207,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("child column \"%s\" specifies generation expression",
-										def->colname),
+										inhdef->colname),
 								 errhint("A child table column cannot be generated unless its parent column is.")));
 				}
 
@@ -3210,12 +3216,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 */
 				if (newdef->raw_default != NULL)
 				{
-					def->raw_default = newdef->raw_default;
-					def->cooked_default = newdef->cooked_default;
+					inhdef->raw_default = newdef->raw_default;
+					inhdef->cooked_default = newdef->cooked_default;
 				}
 
 				/* Mark the column as locally defined */
-				def->is_local = true;
+				inhdef->is_local = true;
 			}
 			else
 			{
-- 
2.43.0

From 2553d082b16db2c54f2e1e4a66f1a57ecabf3c1e Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Date: Wed, 24 Jan 2024 11:15:15 +0530
Subject: [PATCH 2/4] Mark NULL constraint in merged definition instead of new
 definition

This is a typo/thinko in previous commit.

Also fix pgindent issue.

Ashutosh Bapat
---
 src/backend/commands/tablecmds.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 04e674bbda..cde524083e 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2726,8 +2726,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 			/*
 			 * Regular inheritance children are independent enough not to
-			 * inherit identity columns.  But partitions are integral part
-			 * of a partitioned table and inherit identity column.
+			 * inherit identity columns.  But partitions are integral part of
+			 * a partitioned table and inherit identity column.
 			 */
 			if (is_partition)
 				newdef->identity = attribute->attidentity;
@@ -2844,7 +2844,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					newdef->is_not_null = true;
+					prevdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
-- 
2.25.1

From 092828a7d7274b48bf33c88863a97585bff80ebb Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Date: Tue, 23 Jan 2024 17:00:43 +0530
Subject: [PATCH 4/4] Separate function to merge next parent attribute

Partition inherit from only a single parent.  The logic to merge an
attribute from the next parent into the corresponding attribute
inherited from previous parents in MergeAttribute() is only applicable
to regular inheritance children.  This code is isolated enough that it
can be separate into a function by itself.  This separation makes
MergeAttributes() more readable making it easy to follow high level
logic without getting entangled into details.

This separation revealed that the code handling NOT NULL constraints is
duplicated in blocks merging the attribute definition incrementally.
Deduplicate that code.

Author: Ashutosh Bapat
---
 src/backend/commands/tablecmds.c | 352 ++++++++++++++++---------------
 1 file changed, 178 insertions(+), 174 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 843cc3bff6..3f0066b435 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -360,6 +360,8 @@ static List *MergeAttributes(List *columns, const List *supers, char relpersiste
 							 List **supnotnulls);
 static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
 static bool MergeChildAttribute(ColumnDef *newdef, int newcol_attno, List *inh_columns);
+static ColumnDef *MergeInheritedAttribute(ColumnDef *newdef, int parent_attno,
+										  List *inh_columns, AttrMap *newattmap);
 static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel, bool ispartition);
 static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
 static void StoreCatalogInheritance(Oid relationId, List *supers,
@@ -2704,9 +2706,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
-			int			exist_attno;
 			ColumnDef  *newdef;
-			ColumnDef  *savedef;
+			ColumnDef  *mergedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2727,194 +2728,64 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 			/*
 			 * Regular inheritance children are independent enough not to
-			 * inherit identity columns.  But partitions are integral part of
-			 * a partitioned table and inherit identity column.
+			 * inherit identity columns. But partitions are integral part of a
+			 * partitioned table and inherit identity column.
 			 */
 			if (is_partition)
 				newdef->identity = attribute->attidentity;
 
+			mergedef = MergeInheritedAttribute(newdef, parent_attno,
+											   inh_columns, newattmap);
+
 			/*
-			 * Does it match some previously considered column from another
-			 * parent?
+			 * Partitions have only one parent, so conflict should never
+			 * occur.
 			 */
-			exist_attno = findAttrByName(attributeName, inh_columns);
-			if (exist_attno > 0)
-			{
-				ColumnDef  *prevdef;
-				Oid			prevtypeid,
-							newtypeid;
-				int32		prevtypmod,
-							newtypmod;
-				Oid			prevcollid,
-							newcollid;
-
-				/*
-				 * Partitions have only one parent and have no column
-				 * definitions of their own, so conflict should never occur.
-				 */
-				Assert(!is_partition);
-
-				/*
-				 * Yes, try to merge the two column definitions.
-				 */
-				ereport(NOTICE,
-						(errmsg("merging multiple inherited definitions of column \"%s\"",
-								attributeName)));
-				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
-
-				/*
-				 * Must have the same type and typmod
-				 */
-				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
-				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("inherited column \"%s\" has a type conflict",
-									attributeName),
-							 errdetail("%s versus %s",
-									   format_type_with_typemod(prevtypeid, prevtypmod),
-									   format_type_with_typemod(newtypeid, newtypmod))));
-
-				/*
-				 * Must have the same collation
-				 */
-				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
-				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
-				if (prevcollid != newcollid)
-					ereport(ERROR,
-							(errcode(ERRCODE_COLLATION_MISMATCH),
-							 errmsg("inherited column \"%s\" has a collation conflict",
-									attributeName),
-							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(prevcollid),
-									   get_collation_name(newcollid))));
+			Assert(mergedef == NULL || !is_partition);
 
-				/*
-				 * Copy/check storage parameter
-				 */
-				if (prevdef->storage == 0)
-					prevdef->storage = newdef->storage;
-				else if (prevdef->storage != newdef->storage)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("inherited column \"%s\" has a storage parameter conflict",
-									attributeName),
-							 errdetail("%s versus %s",
-									   storage_name(prevdef->storage),
-									   storage_name(newdef->storage))));
-
-				/*
-				 * Copy/check compression parameter
-				 */
-				if (prevdef->compression == NULL)
-					prevdef->compression = newdef->compression;
-				else if (strcmp(prevdef->compression, newdef->compression) != 0)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("column \"%s\" has a compression method conflict",
-									attributeName),
-							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
-
-				/*
-				 * In regular inheritance, columns in the parent's primary key
-				 * get an extra not-null constraint.
-				 */
-				if (bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
-								  pkattrs))
-				{
-					CookedConstraint *nn;
-
-					nn = palloc(sizeof(CookedConstraint));
-					nn->contype = CONSTR_NOTNULL;
-					nn->conoid = InvalidOid;
-					nn->name = NULL;
-					nn->attnum = exist_attno;
-					nn->expr = NULL;
-					nn->skip_validation = false;
-					nn->is_local = false;
-					nn->inhcount = 1;
-					nn->is_no_inherit = false;
-
-					nnconstraints = lappend(nnconstraints, nn);
-				}
-
-				/*
-				 * mark attnotnull if parent has it and it's not NO INHERIT
-				 */
-				if (bms_is_member(parent_attno, nncols) ||
-					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
-								  pkattrs))
-					prevdef->is_not_null = true;
-
-				/*
-				 * Check for GENERATED conflicts
-				 */
-				if (prevdef->generated != newdef->generated)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("inherited column \"%s\" has a generation conflict",
-									attributeName)));
-
-				/*
-				 * Default and other constraints are handled below
-				 */
-
-				prevdef->inhcount++;
-				if (prevdef->inhcount < 0)
-					ereport(ERROR,
-							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-							errmsg("too many inheritance parents"));
-
-				newattmap->attnums[parent_attno - 1] = exist_attno;
-
-				/* remember for default processing below */
-				savedef = prevdef;
-			}
-			else
+			if (mergedef == NULL)
 			{
 				/*
 				 * No, create a new inherited column
 				 */
 				newdef->inhcount = 1;
 				newdef->is_local = false;
-				/* mark attnotnull if parent has it and it's not NO INHERIT */
-				if (bms_is_member(parent_attno, nncols) ||
-					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
-								  pkattrs))
-					newdef->is_not_null = true;
 				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
-				/*
-				 * In regular inheritance, columns in the parent's primary key
-				 * get an extra not-null constraint.  Partitioning doesn't
-				 * need this, because the PK itself is going to be cloned to
-				 * the partition.
-				 */
-				if (!is_partition &&
-					bms_is_member(parent_attno -
-								  FirstLowInvalidHeapAttributeNumber,
-								  pkattrs))
-				{
-					CookedConstraint *nn;
-
-					nn = palloc(sizeof(CookedConstraint));
-					nn->contype = CONSTR_NOTNULL;
-					nn->conoid = InvalidOid;
-					nn->name = NULL;
-					nn->attnum = newattmap->attnums[parent_attno - 1];
-					nn->expr = NULL;
-					nn->skip_validation = false;
-					nn->is_local = false;
-					nn->inhcount = 1;
-					nn->is_no_inherit = false;
-
-					nnconstraints = lappend(nnconstraints, nn);
-				}
+				mergedef = newdef;
+			}
+
+			/* mark attnotnull if parent has it and it's not NO INHERIT */
+			if (bms_is_member(parent_attno, nncols) ||
+				bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
+							  pkattrs))
+				mergedef->is_not_null = true;
 
-				/* remember for default processing below */
-				savedef = newdef;
+			/*
+			 * In regular inheritance, columns in the parent's primary key get
+			 * an extra not-null constraint.  Partitioning doesn't need this,
+			 * because the PK itself is going to be cloned to the partition.
+			 */
+			if (!is_partition &&
+				bms_is_member(parent_attno -
+							  FirstLowInvalidHeapAttributeNumber,
+							  pkattrs))
+			{
+				CookedConstraint *nn;
+
+				nn = palloc(sizeof(CookedConstraint));
+				nn->contype = CONSTR_NOTNULL;
+				nn->conoid = InvalidOid;
+				nn->name = NULL;
+				nn->attnum = newattmap->attnums[parent_attno - 1];
+				nn->expr = NULL;
+				nn->skip_validation = false;
+				nn->is_local = false;
+				nn->inhcount = 1;
+				nn->is_no_inherit = false;
+
+				nnconstraints = lappend(nnconstraints, nn);
 			}
 
 			/*
@@ -2936,7 +2807,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, savedef);
+				cols_with_defaults = lappend(cols_with_defaults, mergedef);
 			}
 		}
 
@@ -3451,6 +3322,139 @@ MergeChildAttribute(ColumnDef *newdef, int newcol_attno, List *inh_columns)
 	return true;
 }
 
+/*
+ * MergeInheritedAttribute
+ *		Merge given parent attribute definition into any attribute, with
+ *  the same name, inherited from the previous parents.
+ *
+ * Input arguments:
+ * 'newdef' is the new parent column/attribute definition to be merged.
+ * 'parent_attno' is the attribute number in parent table's schema definition
+ * 'inh_columns' is the list of previously inherited ColumnDefs.
+ * 'newattmap' is attribute map.
+ *
+ * Return value:
+ * True if the given attribute is merged into a previously inherited attribute
+ * with the same name. False if no matching inherited attribute is found. When
+ * returning true, matching ColumnDef in 'inh_columns' list is modified.
+ * 'newattmap' is updated with matching inherited attribute's position. New
+ * attribute's ColumnDef remains unchanged.
+ *
+ * Notes:
+ *  (1) The attribute is merged according to the rules laid out in the prologue
+ *  of MergeAttributes().
+ *  (2) If matching inherited attribute exists but the new attribute can not
+ *  be merged into it, the function throws respective errors.
+ *  (3) A partition inherits from only a single parent. Hence this
+ *  function is applicable only to a regular inheritance.
+ */
+static ColumnDef *
+MergeInheritedAttribute(ColumnDef *newdef, int parent_attno, List *inh_columns,
+						AttrMap *newattmap)
+{
+	char	   *attributeName = newdef->colname;
+	int			exist_attno;
+	ColumnDef  *prevdef;
+	Oid			prevtypeid,
+				newtypeid;
+	int32		prevtypmod,
+				newtypmod;
+	Oid			prevcollid,
+				newcollid;
+
+	/*
+	 * Does it match some previously considered column from another parent?
+	 */
+	exist_attno = findAttrByName(attributeName, inh_columns);
+	if (exist_attno <= 0)
+		return NULL;
+
+	/*
+	 * Yes, try to merge the two column definitions.
+	 */
+	ereport(NOTICE,
+			(errmsg("merging multiple inherited definitions of column \"%s\"",
+					attributeName)));
+	prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
+
+	/*
+	 * Must have the same type and typmod
+	 */
+	typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+	typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+	if (prevtypeid != newtypeid || prevtypmod != newtypmod)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("inherited column \"%s\" has a type conflict",
+						attributeName),
+				 errdetail("%s versus %s",
+						   format_type_with_typemod(prevtypeid, prevtypmod),
+						   format_type_with_typemod(newtypeid, newtypmod))));
+
+	/*
+	 * Must have the same collation
+	 */
+	prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+	newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+	if (prevcollid != newcollid)
+		ereport(ERROR,
+				(errcode(ERRCODE_COLLATION_MISMATCH),
+				 errmsg("inherited column \"%s\" has a collation conflict",
+						attributeName),
+				 errdetail("\"%s\" versus \"%s\"",
+						   get_collation_name(prevcollid),
+						   get_collation_name(newcollid))));
+
+	/*
+	 * Copy/check storage parameter
+	 */
+	if (prevdef->storage == 0)
+		prevdef->storage = newdef->storage;
+	else if (prevdef->storage != newdef->storage)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("inherited column \"%s\" has a storage parameter conflict",
+						attributeName),
+				 errdetail("%s versus %s",
+						   storage_name(prevdef->storage),
+						   storage_name(newdef->storage))));
+
+	/*
+	 * Copy/check compression parameter
+	 */
+	if (prevdef->compression == NULL)
+		prevdef->compression = newdef->compression;
+	else if (strcmp(prevdef->compression, newdef->compression) != 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("column \"%s\" has a compression method conflict",
+						attributeName),
+				 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
+
+	/*
+	 * Check for GENERATED conflicts
+	 */
+	if (prevdef->generated != newdef->generated)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("inherited column \"%s\" has a generation conflict",
+						attributeName)));
+
+	/*
+	 * Default and other constraints are handled by the caller.
+	 */
+
+	prevdef->inhcount++;
+	if (prevdef->inhcount < 0)
+		ereport(ERROR,
+				errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+				errmsg("too many inheritance parents"));
+
+	newattmap->attnums[parent_attno - 1] = exist_attno;
+
+	return prevdef;
+}
+
 /*
  * StoreCatalogInheritance
  *		Updates the system catalogs with proper inheritance information.
-- 
2.25.1

From 6d6c85d9f08a1d631e4429e9d2c8b3e97b3e1337 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 22 Jan 2024 13:23:43 +0100
Subject: [PATCH 1/4] MergeAttributes: convert pg_attribute back to ColumnDef
 before comparing

MergeAttributes() has a loop to merge multiple inheritance parents
into a column column definition.  The merged-so-far definition is
stored in a ColumnDef node.  If we have to merge columns from multiple
inheritance parents (if the name matches), then we have to check
whether various column properties (type, collation, etc.) match.  The
current code extracts the pg_attribute value of the
currently-considered inheritance parent and compares it against the
merged-so-far ColumnDef value.  If the currently considered column
doesn't match any previously inherited column, we make a new ColumnDef
node from the pg_attribute information and add it to the column list.

This patch rearranges this so that we create the ColumnDef node first
in either case.  Then the code that checks the column properties for
compatibility compares ColumnDef against ColumnDef (instead of
ColumnDef against pg_attribute).  This makes the code more symmetric
and easier to follow.  Also, later in MergeAttributes(), there is a
similar but separate loop that merges the new local column definition
with the combination of the inheritance parents established in the
first loop.  That comparison is already ColumnDef-vs-ColumnDef.  With
this change, both of these can use similar-looking logic.  (A future
project might be to extract these two sets of code into a common
routine that encodes all the knowledge of whether two column
definitions are compatible.  But this isn't currently straightforward
because we want to give different error messages in the two cases.)
Furthermore, by avoiding the use of Form_pg_attribute here, we make it
easier to make changes in the pg_attribute layout without having to
worry about the local needs of tablecmds.c.

Because MergeAttributes() is hugely long, it's sometimes hard to know
where in the function you are currently looking.  To help with that, I
also renamed some variables to make it clearer where you are currently
looking.  The first look is "prev" vs. "new", the second loop is "inh"
vs. "new".

Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org
---
 src/backend/commands/tablecmds.c | 198 ++++++++++++++++---------------
 1 file changed, 102 insertions(+), 96 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2a56a4357c..04e674bbda 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2704,7 +2704,8 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 														parent_attno - 1);
 			char	   *attributeName = NameStr(attribute->attname);
 			int			exist_attno;
-			ColumnDef  *def;
+			ColumnDef  *newdef;
+			ColumnDef  *savedef;
 
 			/*
 			 * Ignore dropped columns in the parent.
@@ -2713,14 +2714,38 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				continue;		/* leave newattmap->attnums entry as zero */
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Create new column definition
+			 */
+			newdef = makeColumnDef(attributeName, attribute->atttypid,
+								   attribute->atttypmod, attribute->attcollation);
+			newdef->storage = attribute->attstorage;
+			newdef->generated = attribute->attgenerated;
+			if (CompressionMethodIsValid(attribute->attcompression))
+				newdef->compression =
+					pstrdup(GetCompressionMethodName(attribute->attcompression));
+
+			/*
+			 * Regular inheritance children are independent enough not to
+			 * inherit identity columns.  But partitions are integral part
+			 * of a partitioned table and inherit identity column.
+			 */
+			if (is_partition)
+				newdef->identity = attribute->attidentity;
+
+			/*
+			 * Does it match some previously considered column from another
+			 * parent?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				Oid			defTypeId;
-				int32		deftypmod;
-				Oid			defCollId;
+				ColumnDef  *prevdef;
+				Oid			prevtypeid,
+							newtypeid;
+				int32		prevtypmod,
+							newtypmod;
+				Oid			prevcollid,
+							newcollid;
 
 				/*
 				 * Partitions have only one parent and have no column
@@ -2734,68 +2759,61 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				ereport(NOTICE,
 						(errmsg("merging multiple inherited definitions of column \"%s\"",
 								attributeName)));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				prevdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				if (defTypeId != attribute->atttypid ||
-					deftypmod != attribute->atttypmod)
+				typenameTypeIdAndMod(NULL, prevdef->typeName, &prevtypeid, &prevtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (prevtypeid != newtypeid || prevtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(attribute->atttypid,
-																attribute->atttypmod))));
+									   format_type_with_typemod(prevtypeid, prevtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defCollId = GetColumnDefCollation(NULL, def, defTypeId);
-				if (defCollId != attribute->attcollation)
+				prevcollid = GetColumnDefCollation(NULL, prevdef, prevtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (prevcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("inherited column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defCollId),
-									   get_collation_name(attribute->attcollation))));
+									   get_collation_name(prevcollid),
+									   get_collation_name(newcollid))));
 
 				/*
 				 * Copy/check storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = attribute->attstorage;
-				else if (def->storage != attribute->attstorage)
+				if (prevdef->storage == 0)
+					prevdef->storage = newdef->storage;
+				else if (prevdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
-									   storage_name(attribute->attstorage))));
+									   storage_name(prevdef->storage),
+									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy/check compression parameter
 				 */
-				if (CompressionMethodIsValid(attribute->attcompression))
-				{
-					const char *compression =
-						GetCompressionMethodName(attribute->attcompression);
-
-					if (def->compression == NULL)
-						def->compression = pstrdup(compression);
-					else if (strcmp(def->compression, compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", def->compression, compression)));
-				}
+				if (prevdef->compression == NULL)
+					prevdef->compression = newdef->compression;
+				else if (strcmp(prevdef->compression, newdef->compression) != 0)
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has a compression method conflict",
+									attributeName),
+							 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
 
 				/*
 				 * In regular inheritance, columns in the parent's primary key
@@ -2826,12 +2844,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
+					newdef->is_not_null = true;
 
 				/*
 				 * Check for GENERATED conflicts
 				 */
-				if (def->generated != attribute->attgenerated)
+				if (prevdef->generated != newdef->generated)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("inherited column \"%s\" has a generation conflict",
@@ -2841,43 +2859,30 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * Default and other constraints are handled below
 				 */
 
-				def->inhcount++;
-				if (def->inhcount < 0)
+				prevdef->inhcount++;
+				if (prevdef->inhcount < 0)
 					ereport(ERROR,
 							errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 							errmsg("too many inheritance parents"));
 
 				newattmap->attnums[parent_attno - 1] = exist_attno;
+
+				/* remember for default processing below */
+				savedef = prevdef;
 			}
 			else
 			{
 				/*
 				 * No, create a new inherited column
 				 */
-				def = makeColumnDef(attributeName, attribute->atttypid,
-									attribute->atttypmod, attribute->attcollation);
-				def->inhcount = 1;
-				def->is_local = false;
+				newdef->inhcount = 1;
+				newdef->is_local = false;
 				/* mark attnotnull if parent has it and it's not NO INHERIT */
 				if (bms_is_member(parent_attno, nncols) ||
 					bms_is_member(parent_attno - FirstLowInvalidHeapAttributeNumber,
 								  pkattrs))
-					def->is_not_null = true;
-				def->storage = attribute->attstorage;
-				def->generated = attribute->attgenerated;
-
-				/*
-				 * Regular inheritance children are independent enough not to
-				 * inherit identity columns.  But partitions are integral part
-				 * of a partitioned table and inherit identity column.
-				 */
-				if (is_partition)
-					def->identity = attribute->attidentity;
-
-				if (CompressionMethodIsValid(attribute->attcompression))
-					def->compression =
-						pstrdup(GetCompressionMethodName(attribute->attcompression));
-				inh_columns = lappend(inh_columns, def);
+					newdef->is_not_null = true;
+				inh_columns = lappend(inh_columns, newdef);
 				newattmap->attnums[parent_attno - 1] = ++child_attno;
 
 				/*
@@ -2906,6 +2911,9 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 					nnconstraints = lappend(nnconstraints, nn);
 				}
+
+				/* remember for default processing below */
+				savedef = newdef;
 			}
 
 			/*
@@ -2927,7 +2935,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * all the inherited default expressions for the moment.
 				 */
 				inherited_defaults = lappend(inherited_defaults, this_default);
-				cols_with_defaults = lappend(cols_with_defaults, def);
+				cols_with_defaults = lappend(cols_with_defaults, savedef);
 			}
 		}
 
@@ -3065,17 +3073,17 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 			newcol_attno++;
 
 			/*
-			 * Does it conflict with some previously inherited column?
+			 * Does it match some inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inh_columns);
 			if (exist_attno > 0)
 			{
-				ColumnDef  *def;
-				Oid			defTypeId,
-							newTypeId;
-				int32		deftypmod,
+				ColumnDef  *inhdef;
+				Oid			inhtypeid,
+							newtypeid;
+				int32		inhtypmod,
 							newtypmod;
-				Oid			defcollid,
+				Oid			inhcollid,
 							newcollid;
 
 				/*
@@ -3095,77 +3103,75 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 					ereport(NOTICE,
 							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
 							 errdetail("User-specified column moved to the position of the inherited column.")));
-				def = (ColumnDef *) list_nth(inh_columns, exist_attno - 1);
+				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
 
 				/*
 				 * Must have the same type and typmod
 				 */
-				typenameTypeIdAndMod(NULL, def->typeName, &defTypeId, &deftypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newTypeId, &newtypmod);
-				if (defTypeId != newTypeId || deftypmod != newtypmod)
+				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a type conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   format_type_with_typemod(defTypeId,
-																deftypmod),
-									   format_type_with_typemod(newTypeId,
-																newtypmod))));
+									   format_type_with_typemod(inhtypeid, inhtypmod),
+									   format_type_with_typemod(newtypeid, newtypmod))));
 
 				/*
 				 * Must have the same collation
 				 */
-				defcollid = GetColumnDefCollation(NULL, def, defTypeId);
-				newcollid = GetColumnDefCollation(NULL, newdef, newTypeId);
-				if (defcollid != newcollid)
+				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+				if (inhcollid != newcollid)
 					ereport(ERROR,
 							(errcode(ERRCODE_COLLATION_MISMATCH),
 							 errmsg("column \"%s\" has a collation conflict",
 									attributeName),
 							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(defcollid),
+									   get_collation_name(inhcollid),
 									   get_collation_name(newcollid))));
 
 				/*
 				 * Identity is never inherited.  The new column can have an
 				 * identity definition, so we always just take that one.
 				 */
-				def->identity = newdef->identity;
+				inhdef->identity = newdef->identity;
 
 				/*
 				 * Copy storage parameter
 				 */
-				if (def->storage == 0)
-					def->storage = newdef->storage;
-				else if (newdef->storage != 0 && def->storage != newdef->storage)
+				if (inhdef->storage == 0)
+					inhdef->storage = newdef->storage;
+				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
 					ereport(ERROR,
 							(errcode(ERRCODE_DATATYPE_MISMATCH),
 							 errmsg("column \"%s\" has a storage parameter conflict",
 									attributeName),
 							 errdetail("%s versus %s",
-									   storage_name(def->storage),
+									   storage_name(inhdef->storage),
 									   storage_name(newdef->storage))));
 
 				/*
 				 * Copy compression parameter
 				 */
-				if (def->compression == NULL)
-					def->compression = newdef->compression;
+				if (inhdef->compression == NULL)
+					inhdef->compression = newdef->compression;
 				else if (newdef->compression != NULL)
 				{
-					if (strcmp(def->compression, newdef->compression) != 0)
+					if (strcmp(inhdef->compression, newdef->compression) != 0)
 						ereport(ERROR,
 								(errcode(ERRCODE_DATATYPE_MISMATCH),
 								 errmsg("column \"%s\" has a compression method conflict",
 										attributeName),
-								 errdetail("%s versus %s", def->compression, newdef->compression)));
+								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
 				}
 
 				/*
 				 * Merge of not-null constraints = OR 'em together
 				 */
-				def->is_not_null |= newdef->is_not_null;
+				inhdef->is_not_null |= newdef->is_not_null;
 
 				/*
 				 * Check for conflicts related to generated columns.
@@ -3182,18 +3188,18 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 * it results in being able to override the generation
 				 * expression via UPDATEs through the parent.)
 				 */
-				if (def->generated)
+				if (inhdef->generated)
 				{
 					if (newdef->raw_default && !newdef->generated)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										def->colname)));
+										inhdef->colname)));
 					if (newdef->identity)
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										def->colname)));
+										inhdef->colname)));
 				}
 				else
 				{
@@ -3201,7 +3207,7 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 						ereport(ERROR,
 								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
 								 errmsg("child column \"%s\" specifies generation expression",
-										def->colname),
+										inhdef->colname),
 								 errhint("A child table column cannot be generated unless its parent column is.")));
 				}
 
@@ -3210,12 +3216,12 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 				 */
 				if (newdef->raw_default != NULL)
 				{
-					def->raw_default = newdef->raw_default;
-					def->cooked_default = newdef->cooked_default;
+					inhdef->raw_default = newdef->raw_default;
+					inhdef->cooked_default = newdef->cooked_default;
 				}
 
 				/* Mark the column as locally defined */
-				def->is_local = true;
+				inhdef->is_local = true;
 			}
 			else
 			{
-- 
2.25.1

From e8993ab2e00db5f8260ef9d9cafe9fbe069d54a2 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Date: Tue, 23 Jan 2024 12:47:46 +0530
Subject: [PATCH 3/4] Separate function to merge a child attribute into
 matching inherited attribute

The logic to merge a child attribute into matching inherited attribute
in MergeAttribute() is only applicable to regular inheritance child. The
code is isolated and coherent enough that it can be separated into a
function of its own. This separation also makes MergeAttribute() more
readable by making it easier to follow high level logic without getting
entangled into details.

Author: Ashutosh Bapat
---
 src/backend/commands/tablecmds.c | 337 +++++++++++++++++--------------
 1 file changed, 184 insertions(+), 153 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index cde524083e..843cc3bff6 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -359,6 +359,7 @@ static List *MergeAttributes(List *columns, const List *supers, char relpersiste
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
 static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
+static bool MergeChildAttribute(ColumnDef *newdef, int newcol_attno, List *inh_columns);
 static void MergeAttributesIntoExisting(Relation child_rel, Relation parent_rel, bool ispartition);
 static void MergeConstraintsIntoExisting(Relation child_rel, Relation parent_rel);
 static void StoreCatalogInheritance(Oid relationId, List *supers,
@@ -3066,167 +3067,21 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 
 		foreach(lc, columns)
 		{
-			ColumnDef  *newdef = lfirst(lc);
-			char	   *attributeName = newdef->colname;
-			int			exist_attno;
+			ColumnDef  *newdef = lfirst_node(ColumnDef, lc);
 
 			newcol_attno++;
 
 			/*
-			 * Does it match some inherited column?
+			 * Partitions have only one parent and have no column definitions
+			 * of their own, so conflict should never occur.
 			 */
-			exist_attno = findAttrByName(attributeName, inh_columns);
-			if (exist_attno > 0)
-			{
-				ColumnDef  *inhdef;
-				Oid			inhtypeid,
-							newtypeid;
-				int32		inhtypmod,
-							newtypmod;
-				Oid			inhcollid,
-							newcollid;
-
-				/*
-				 * Partitions have only one parent and have no column
-				 * definitions of their own, so conflict should never occur.
-				 */
-				Assert(!is_partition);
-
-				/*
-				 * Yes, try to merge the two column definitions.
-				 */
-				if (exist_attno == newcol_attno)
-					ereport(NOTICE,
-							(errmsg("merging column \"%s\" with inherited definition",
-									attributeName)));
-				else
-					ereport(NOTICE,
-							(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
-							 errdetail("User-specified column moved to the position of the inherited column.")));
-				inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
-
-				/*
-				 * Must have the same type and typmod
-				 */
-				typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
-				typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
-				if (inhtypeid != newtypeid || inhtypmod != newtypmod)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("column \"%s\" has a type conflict",
-									attributeName),
-							 errdetail("%s versus %s",
-									   format_type_with_typemod(inhtypeid, inhtypmod),
-									   format_type_with_typemod(newtypeid, newtypmod))));
-
-				/*
-				 * Must have the same collation
-				 */
-				inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
-				newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
-				if (inhcollid != newcollid)
-					ereport(ERROR,
-							(errcode(ERRCODE_COLLATION_MISMATCH),
-							 errmsg("column \"%s\" has a collation conflict",
-									attributeName),
-							 errdetail("\"%s\" versus \"%s\"",
-									   get_collation_name(inhcollid),
-									   get_collation_name(newcollid))));
-
-				/*
-				 * Identity is never inherited.  The new column can have an
-				 * identity definition, so we always just take that one.
-				 */
-				inhdef->identity = newdef->identity;
-
-				/*
-				 * Copy storage parameter
-				 */
-				if (inhdef->storage == 0)
-					inhdef->storage = newdef->storage;
-				else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
-					ereport(ERROR,
-							(errcode(ERRCODE_DATATYPE_MISMATCH),
-							 errmsg("column \"%s\" has a storage parameter conflict",
-									attributeName),
-							 errdetail("%s versus %s",
-									   storage_name(inhdef->storage),
-									   storage_name(newdef->storage))));
-
-				/*
-				 * Copy compression parameter
-				 */
-				if (inhdef->compression == NULL)
-					inhdef->compression = newdef->compression;
-				else if (newdef->compression != NULL)
-				{
-					if (strcmp(inhdef->compression, newdef->compression) != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_DATATYPE_MISMATCH),
-								 errmsg("column \"%s\" has a compression method conflict",
-										attributeName),
-								 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
-				}
-
-				/*
-				 * Merge of not-null constraints = OR 'em together
-				 */
-				inhdef->is_not_null |= newdef->is_not_null;
-
-				/*
-				 * Check for conflicts related to generated columns.
-				 *
-				 * If the parent column is generated, the child column will be
-				 * made a generated column if it isn't already.  If it is a
-				 * generated column, we'll take its generation expression in
-				 * preference to the parent's.  We must check that the child
-				 * column doesn't specify a default value or identity, which
-				 * matches the rules for a single column in parse_utilcmd.c.
-				 *
-				 * Conversely, if the parent column is not generated, the
-				 * child column can't be either.  (We used to allow that, but
-				 * it results in being able to override the generation
-				 * expression via UPDATEs through the parent.)
-				 */
-				if (inhdef->generated)
-				{
-					if (newdef->raw_default && !newdef->generated)
-						ereport(ERROR,
-								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
-								 errmsg("column \"%s\" inherits from generated column but specifies default",
-										inhdef->colname)));
-					if (newdef->identity)
-						ereport(ERROR,
-								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
-								 errmsg("column \"%s\" inherits from generated column but specifies identity",
-										inhdef->colname)));
-				}
-				else
-				{
-					if (newdef->generated)
-						ereport(ERROR,
-								(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
-								 errmsg("child column \"%s\" specifies generation expression",
-										inhdef->colname),
-								 errhint("A child table column cannot be generated unless its parent column is.")));
-				}
-
-				/*
-				 * If new def has a default, override previous default
-				 */
-				if (newdef->raw_default != NULL)
-				{
-					inhdef->raw_default = newdef->raw_default;
-					inhdef->cooked_default = newdef->cooked_default;
-				}
+			Assert(!is_partition);
 
-				/* Mark the column as locally defined */
-				inhdef->is_local = true;
-			}
-			else
+			if (!MergeChildAttribute(newdef, newcol_attno, inh_columns))
 			{
 				/*
-				 * No, attach new column to result columns
+				 * No inherited attribute, attach new column to result
+				 * columns.
 				 */
 				inh_columns = lappend(inh_columns, newdef);
 			}
@@ -3419,6 +3274,182 @@ MergeCheckConstraint(List *constraints, const char *name, Node *expr)
 	return lappend(constraints, newcon);
 }
 
+/*
+ * MergeChildAttribute
+ *		Merge given child attribute definition into any inherited attribute with
+ *  the same name.
+ *
+ * Input arguments:
+ * 'newdef' is the column/attribute definition from the child table.
+ * 'newcol_attno' is the attribute number in child table's schema definition
+ * 'inh_columns' is the list of inherited ColumnDefs.
+ *
+ * Return value:
+ * True if the given attribute is merged into an inherited attribute with the
+ * same name. False if no matching inherited attribute is found. When returning
+ * true, matching ColumnDef in 'inh_columns' list is modified. Child
+ * attribute's ColumnDef remains unchanged.
+ *
+ * Notes:
+ *  (1) The attribute is merged according to the rules laid out in the prologue
+ *  of MergeAttributes().
+ *  (2) If matching inherited attribute exists but the child attribute can not
+ *  be merged into it, the function throws respective errors.
+ *  (3) A partition can not have its own column definitions. Hence this
+ *  function is applicable only to a regular inheritance child.
+ */
+static bool
+MergeChildAttribute(ColumnDef *newdef, int newcol_attno, List *inh_columns)
+{
+	char	   *attributeName = newdef->colname;
+	int			exist_attno;
+	ColumnDef  *inhdef;
+	Oid			inhtypeid,
+				newtypeid;
+	int32		inhtypmod,
+				newtypmod;
+	Oid			inhcollid,
+				newcollid;
+
+	/*
+	 * Does it match some inherited column?
+	 */
+	exist_attno = findAttrByName(attributeName, inh_columns);
+	if (exist_attno <= 0)
+		return false;
+
+	/*
+	 * Yes, try to merge the two column definitions.
+	 */
+	if (exist_attno == newcol_attno)
+		ereport(NOTICE,
+				(errmsg("merging column \"%s\" with inherited definition",
+						attributeName)));
+	else
+		ereport(NOTICE,
+				(errmsg("moving and merging column \"%s\" with inherited definition", attributeName),
+				 errdetail("User-specified column moved to the position of the inherited column.")));
+	inhdef = list_nth_node(ColumnDef, inh_columns, exist_attno - 1);
+
+	/*
+	 * Must have the same type and typmod
+	 */
+	typenameTypeIdAndMod(NULL, inhdef->typeName, &inhtypeid, &inhtypmod);
+	typenameTypeIdAndMod(NULL, newdef->typeName, &newtypeid, &newtypmod);
+	if (inhtypeid != newtypeid || inhtypmod != newtypmod)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("column \"%s\" has a type conflict",
+						attributeName),
+				 errdetail("%s versus %s",
+						   format_type_with_typemod(inhtypeid, inhtypmod),
+						   format_type_with_typemod(newtypeid, newtypmod))));
+
+	/*
+	 * Must have the same collation
+	 */
+	inhcollid = GetColumnDefCollation(NULL, inhdef, inhtypeid);
+	newcollid = GetColumnDefCollation(NULL, newdef, newtypeid);
+	if (inhcollid != newcollid)
+		ereport(ERROR,
+				(errcode(ERRCODE_COLLATION_MISMATCH),
+				 errmsg("column \"%s\" has a collation conflict",
+						attributeName),
+				 errdetail("\"%s\" versus \"%s\"",
+						   get_collation_name(inhcollid),
+						   get_collation_name(newcollid))));
+
+	/*
+	 * Identity is never inherited by a regular inheritance child. Pick
+	 * child's identity definition if there's one.
+	 */
+	inhdef->identity = newdef->identity;
+
+	/*
+	 * Copy storage parameter
+	 */
+	if (inhdef->storage == 0)
+		inhdef->storage = newdef->storage;
+	else if (newdef->storage != 0 && inhdef->storage != newdef->storage)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("column \"%s\" has a storage parameter conflict",
+						attributeName),
+				 errdetail("%s versus %s",
+						   storage_name(inhdef->storage),
+						   storage_name(newdef->storage))));
+
+	/*
+	 * Copy compression parameter
+	 */
+	if (inhdef->compression == NULL)
+		inhdef->compression = newdef->compression;
+	else if (newdef->compression != NULL)
+	{
+		if (strcmp(inhdef->compression, newdef->compression) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("column \"%s\" has a compression method conflict",
+							attributeName),
+					 errdetail("%s versus %s", inhdef->compression, newdef->compression)));
+	}
+
+	/*
+	 * Merge of not-null constraints = OR 'em together
+	 */
+	inhdef->is_not_null |= newdef->is_not_null;
+
+	/*
+	 * Check for conflicts related to generated columns.
+	 *
+	 * If the parent column is generated, the child column will be made a
+	 * generated column if it isn't already.  If it is a generated column,
+	 * we'll take its generation expression in preference to the parent's.  We
+	 * must check that the child column doesn't specify a default value or
+	 * identity, which matches the rules for a single column in
+	 * parse_utilcmd.c.
+	 *
+	 * Conversely, if the parent column is not generated, the child column
+	 * can't be either.  (We used to allow that, but it results in being able
+	 * to override the generation expression via UPDATEs through the parent.)
+	 */
+	if (inhdef->generated)
+	{
+		if (newdef->raw_default && !newdef->generated)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
+					 errmsg("column \"%s\" inherits from generated column but specifies default",
+							inhdef->colname)));
+		if (newdef->identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
+					 errmsg("column \"%s\" inherits from generated column but specifies identity",
+							inhdef->colname)));
+	}
+	else
+	{
+		if (newdef->generated)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_COLUMN_DEFINITION),
+					 errmsg("child column \"%s\" specifies generation expression",
+							inhdef->colname),
+					 errhint("A child table column cannot be generated unless its parent column is.")));
+	}
+
+	/*
+	 * If new def has a default, override previous default
+	 */
+	if (newdef->raw_default != NULL)
+	{
+		inhdef->raw_default = newdef->raw_default;
+		inhdef->cooked_default = newdef->cooked_default;
+	}
+
+	/* Mark the column as locally defined */
+	inhdef->is_local = true;
+
+	return true;
+}
 
 /*
  * StoreCatalogInheritance
-- 
2.25.1

From 7c1ff7b17933eef9523486a2c0a054836db9cf24 Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
Date: Tue, 30 Apr 2024 11:19:43 +0530
Subject: [PATCH] Fix segmentation fault in MergeInheritedAttribute()

While converting a pg_attribute tuple into a ColumnDef, ColumnDef::compression
remains NULL if there is no compression method set fot the attribute. Calling
strcmp() with NULL ColumnDef::compression, when comparing compression methods
of parents, causes segmentation fault in MergeInheritedAttribute(). Skip
comparing compression methods if either of them is NULL.

Author: Ashutosh Bapat
Discussion: https://www.postgresql.org/message-id/b22a6834-aacb-7b18-0424-a3f5fe889667%40gmail.com
---
 src/backend/commands/tablecmds.c          | 16 ++++++++++------
 src/test/regress/expected/compression.out | 10 +++++++---
 src/test/regress/sql/compression.sql      |  8 +++++---
 3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3556240c8e..e29f96e357 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -3430,12 +3430,16 @@ MergeInheritedAttribute(List *inh_columns,
 	 */
 	if (prevdef->compression == NULL)
 		prevdef->compression = newdef->compression;
-	else if (strcmp(prevdef->compression, newdef->compression) != 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATATYPE_MISMATCH),
-				 errmsg("column \"%s\" has a compression method conflict",
-						attributeName),
-				 errdetail("%s versus %s", prevdef->compression, newdef->compression)));
+	else if (newdef->compression != NULL)
+	{
+		if (strcmp(prevdef->compression, newdef->compression) != 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("column \"%s\" has a compression method conflict",
+							attributeName),
+					 errdetail("%s versus %s",
+							   prevdef->compression, newdef->compression)));
+	}
 
 	/*
 	 * Check for GENERATED conflicts
diff --git a/src/test/regress/expected/compression.out b/src/test/regress/expected/compression.out
index 834b7555cb..4dd9ee7200 100644
--- a/src/test/regress/expected/compression.out
+++ b/src/test/regress/expected/compression.out
@@ -223,15 +223,18 @@ SELECT pg_column_compression(f1) FROM cmpart2;
  pglz
 (1 row)
 
--- test compression with inheritance, error
-CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
+-- test compression with inheritance
+CREATE TABLE cminh() INHERITS(cmdata, cmdata1); -- error
 NOTICE:  merging multiple inherited definitions of column "f1"
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
-CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
+CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata); -- error
 NOTICE:  merging column "f1" with inherited definition
 ERROR:  column "f1" has a compression method conflict
 DETAIL:  pglz versus lz4
+CREATE TABLE cmdata3(f1 text);
+CREATE TABLE cminh() INHERITS (cmdata, cmdata3);
+NOTICE:  merging multiple inherited definitions of column "f1"
 -- test default_toast_compression GUC
 SET default_toast_compression = '';
 ERROR:  invalid value for parameter "default_toast_compression": ""
@@ -251,6 +254,7 @@ INSERT INTO cmdata VALUES (repeat('123456789', 4004));
  f1     | text |           |          |         | extended | lz4         |              | 
 Indexes:
     "idx" btree (f1)
+Child tables: cminh
 
 SELECT pg_column_compression(f1) FROM cmdata;
  pg_column_compression 
diff --git a/src/test/regress/sql/compression.sql b/src/test/regress/sql/compression.sql
index 7179a5002e..490595fcfb 100644
--- a/src/test/regress/sql/compression.sql
+++ b/src/test/regress/sql/compression.sql
@@ -93,9 +93,11 @@ INSERT INTO cmpart VALUES (repeat('123456789', 4004));
 SELECT pg_column_compression(f1) FROM cmpart1;
 SELECT pg_column_compression(f1) FROM cmpart2;
 
--- test compression with inheritance, error
-CREATE TABLE cminh() INHERITS(cmdata, cmdata1);
-CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata);
+-- test compression with inheritance
+CREATE TABLE cminh() INHERITS(cmdata, cmdata1); -- error
+CREATE TABLE cminh(f1 TEXT COMPRESSION lz4) INHERITS(cmdata); -- error
+CREATE TABLE cmdata3(f1 text);
+CREATE TABLE cminh() INHERITS (cmdata, cmdata3);
 
 -- test default_toast_compression GUC
 SET default_toast_compression = '';
-- 
2.34.1