identity columns

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 29738b0..027c73e 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1095,6 +1095,17 @@ <title><structname>pg_attribute</> Columns</title>
      </row>
 
      <row>
+      <entry><structfield>attidentity</structfield></entry>
+      <entry><type>char</type></entry>
+      <entry></entry>
+      <entry>
+       If a space character, then not an identity column.  Otherwise,
+       <literal>a</literal> = generated always, <literal>d</literal> =
+       generated by default.
+      </entry>
+     </row>
+
+     <row>
       <entry><structfield>attisdropped</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index c43e325..8ece439 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -1583,13 +1583,20 @@ <title><literal>columns</literal> Columns</title>
      <row>
       <entry><literal>is_identity</literal></entry>
       <entry><type>yes_or_no</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>YES</literal>,
+       else <literal>NO</literal>.
+      </entry>
      </row>
 
      <row>
       <entry><literal>identity_generation</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>ALWAYS</literal>
+       or <literal>BY DEFAULT</literal>, reflecting the definition of the
+       column.
+      </entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index e48ccf2..b272633 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -42,6 +42,9 @@
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESET } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
@@ -170,6 +173,32 @@ <title>Description</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
+    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
+    <term><literal>DROP IDENTITY</literal></term>
+    <listitem>
+     <para>
+      These forms change whether a column is an identity column or change the
+      generation attribute of an existing identity column.
+      See <xref linkend="sql-createtable"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET <replaceable>sequence_option</replaceable></literal></term>
+    <term><literal>RESET</literal></term>
+    <listitem>
+     <para>
+      These forms alter the sequence that underlies an existing identity
+      column.  <replaceable>sequence_option</replaceable> is an option
+      supported by <xref linkend="sql-altersequence"> such
+      as <literal>INCREMENT BY</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>SET STATISTICS</literal></term>
     <listitem>
      <para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index bf2ad64..1c04f3d 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -49,6 +49,7 @@
   NULL |
   CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
   REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
@@ -68,7 +69,7 @@
 
 <phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
 
-{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
+{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | IDENTITY | INDEXES | STORAGE | COMMENTS | ALL }
 
 <phrase><replaceable class="PARAMETER">index_parameters</replaceable> in <literal>UNIQUE</literal>, <literal>PRIMARY KEY</literal>, and <literal>EXCLUDE</literal> constraints are:</phrase>
 
@@ -338,6 +339,12 @@ <title>Parameters</title>
       the original and new tables.
      </para>
      <para>
+      Any identity specifications of copied column definitions will only be
+      copied if <literal>INCLUDING IDENTITY</literal> is specified.  A new
+      sequence is created for each identity column of the new table, separate
+      from the sequences associated with the old table.
+     </para>
+     <para>
       Not-null constraints are always copied to the new table.
       <literal>CHECK</literal> constraints will be copied only if
       <literal>INCLUDING CONSTRAINTS</literal> is specified.
@@ -369,7 +376,7 @@ <title>Parameters</title>
      </para>
      <para>
       <literal>INCLUDING ALL</literal> is an abbreviated form of
-      <literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
+      <literal>INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
      </para>
      <para>
       Note that unlike <literal>INHERITS</literal>, columns and
@@ -484,6 +491,35 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]</literal></term>
+    <listitem>
+     <para>
+      This clause creates the column as an <firstterm>identity
+      column</firstterm>.  It will have an implicit sequence attached to it
+      and the column in new rows will automatically have values from the
+      sequence assigned to it.
+     </para>
+
+     <para>
+      The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
+      determine how the sequence value is given precedence over a
+      user-specified value in an <command>INSERT</command> statement.
+      If <literal>ALWAYS</literal> is specified, a user-specified value is
+      only accepted if the <command>INSERT</command> statement
+      specifies <literal>OVERRIDING SYSTEM VALUE</literal>.  If <literal>BY
+      DEFAULT</literal> is specified, then the user-specified value takes
+      precedence.  See <xref linkend="sql-insert"> for details.
+     </para>
+
+     <para>
+      The optional <replaceable>sequence_options</replaceable> clause can be
+      used to override the options of the sequence.
+      See <xref linkend="sql-createsequence"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>UNIQUE</> (column constraint)</term>
     <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
 
@@ -1116,7 +1152,7 @@ <title>Notes</title>
 
     <para>
      Using OIDs in new applications is not recommended: where
-     possible, using a <literal>SERIAL</literal> or other sequence
+     possible, using an identity column or other sequence
      generator as the table's primary key is preferred. However, if
      your application does make use of OIDs to identify specific
      rows of a table, it is recommended to create a unique constraint
@@ -1176,7 +1212,7 @@ <title>Examples</title>
 );
 
 CREATE TABLE distributors (
-     did    integer PRIMARY KEY DEFAULT nextval('serial'),
+     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
      name   varchar(40) NOT NULL CHECK (name &lt;&gt; '')
 );
 </programlisting>
@@ -1509,6 +1545,20 @@ <title>Zero-column Tables</title>
   </refsect2>
 
   <refsect2>
+   <title>Multiple Identity Columns</title>
+
+   <para>
+    <productname>PostgreSQL</productname> allows a table to have more than one
+    identity column.  The standard specifies that a table can have at most one
+    identity column.  This is relaxed mainly to give more flexibility for
+    doing schema changes or migrations.  Note that
+    the <command>INSERT</command> command supports only one override clause
+    that applies to the entire statement, so having multiple identity columns
+    with different behaviors is not well supported.
+   </para>
+  </refsect2>
+
+  <refsect2>
    <title><literal>LIKE</> Clause</title>
 
    <para>
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 06f4160..69b15d0 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -23,6 +23,7 @@
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
 INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replaceable class="parameter">alias</replaceable> ] [ ( <replaceable class="PARAMETER">column_name</replaceable> [, ...] ) ]
+    [ OVERRIDING { SYSTEM | USER} VALUE ]
     { DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
     [ ON CONFLICT [ <replaceable class="parameter">conflict_target</replaceable> ] <replaceable class="parameter">conflict_action</replaceable> ]
     [ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@@ -202,10 +203,43 @@ <title id="sql-inserting-params-title">Inserting</title>
      </varlistentry>
 
      <varlistentry>
+      <term><literal>OVERRIDING SYSTEM VALUE</literal></term>
+      <listitem>
+       <para>
+        Without this clause, it is an error to specify an explicit value
+        (other than <literal>DEFAULT</literal>) for an identity column defined
+        as <literal>GENERATED ALWAYS</literal>.  This clause overrides that
+        restriction.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>OVERRIDING USER VALUE</literal></term>
+      <listitem>
+       <para>
+        If this clause is specified, then any values supplied for identity
+        columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
+        and the default sequence-generated values are applied.
+       </para>
+
+       <para>
+        This clause is useful for example when copying values between tables.
+        Writing <literal>INSERT INTO tbl2 OVERRIDING USER VALUE SELECT * FROM
+        tbl1</literal> will copy from <literal>tbl1</literal> all columns that
+        are not identity columns in <literal>tbl2</literal> but will continue
+        the sequence counters for any identity columns.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>DEFAULT VALUES</literal></term>
       <listitem>
        <para>
         All columns will be filled with their default values.
+        (An <literal>OVERRIDING</literal> clause is not permitted in this
+        form.)
        </para>
       </listitem>
      </varlistentry>
@@ -700,6 +734,13 @@ <title>Compatibility</title>
   </para>
 
   <para>
+   The SQL standard specifies that <literal>OVERRIDING SYSTEM VALUE</literal>
+   can only be specified if an identity column that is generated always
+   exists.  PostgreSQL allows the clause in any case and ignores it if it is
+   not applicable.
+  </para>
+
+  <para>
    Possible limitations of the <replaceable
    class="PARAMETER">query</replaceable> clause are documented under
    <xref linkend="sql-select">.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index b56d0e3..8a8244e 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -149,6 +149,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 		desc->attrs[i]->attnotnull = false;
 		desc->attrs[i]->atthasdef = false;
+		desc->attrs[i]->attidentity = ' ';
 	}
 
 	desc->tdtypeid = tupdesc->tdtypeid;
@@ -256,6 +257,7 @@ TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 	/* since we're not copying constraints or defaults, clear these */
 	dst->attrs[dstAttno - 1]->attnotnull = false;
 	dst->attrs[dstAttno - 1]->atthasdef = false;
+	dst->attrs[dstAttno - 1]->attidentity = ' ';
 }
 
 /*
@@ -400,6 +402,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atthasdef != attr2->atthasdef)
 			return false;
+		if (attr1->attidentity != attr2->attidentity)
+			return false;
 		if (attr1->attisdropped != attr2->attisdropped)
 			return false;
 		if (attr1->attislocal != attr2->attislocal)
@@ -533,6 +537,7 @@ TupleDescInitEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = ' ';
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 26d1652..f0d79c3 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -409,6 +409,7 @@ sub emit_pgattr_row
 		attcacheoff   => '-1',
 		atttypmod     => '-1',
 		atthasdef     => 'f',
+		attidentity   => "' '",
 		attisdropped  => 'f',
 		attislocal    => 't',
 		attinhcount   => '0',
@@ -425,6 +426,7 @@ sub bki_insert
 	my @attnames   = @_;
 	my $oid        = $row->{oid} ? "OID = $row->{oid} " : '';
 	my $bki_values = join ' ', map $row->{$_}, @attnames;
+	$bki_values =~ s/'/"/g;
 	printf BKI "insert %s( %s)\n", $oid, $bki_values;
 }
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 0cf7b9e..c88771f 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -139,37 +139,37 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
 static FormData_pg_attribute a1 = {
 	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
 	SelfItemPointerAttributeNumber, 0, -1, -1,
-	false, 'p', 's', true, false, false, true, 0
+	false, 'p', 's', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a2 = {
 	0, {"oid"}, OIDOID, 0, sizeof(Oid),
 	ObjectIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a3 = {
 	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
 	MinTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a4 = {
 	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
 	MinCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a5 = {
 	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
 	MaxTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a6 = {
 	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
 	MaxCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 /*
@@ -181,7 +181,7 @@ static FormData_pg_attribute a6 = {
 static FormData_pg_attribute a7 = {
 	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
 	TableOidAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
@@ -625,6 +625,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
 	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
 	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
+	values[Anum_pg_attribute_attidentity - 1] = CharGetDatum(new_attribute->attidentity);
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 08b646d..479fb6f 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -353,6 +353,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->attnotnull = false;
 			to->atthasdef = false;
+			to->attidentity = ' ';
 			to->attislocal = true;
 			to->attinhcount = 0;
 			to->attcollation = collationObjectId[i];
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index 00550eb..bd4cf7a 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -646,7 +646,7 @@ CREATE VIEW columns AS
            CAST(c.relname AS sql_identifier) AS table_name,
            CAST(a.attname AS sql_identifier) AS column_name,
            CAST(a.attnum AS cardinal_number) AS ordinal_position,
-           CAST(pg_get_expr(ad.adbin, ad.adrelid) AS character_data) AS column_default,
+           CAST(CASE WHEN a.atthasdef AND a.attidentity = ' ' THEN pg_get_expr(ad.adbin, ad.adrelid) END AS character_data) AS column_default,
            CAST(CASE WHEN a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) THEN 'NO' ELSE 'YES' END
              AS yes_or_no)
              AS is_nullable,
@@ -727,13 +727,13 @@ CREATE VIEW columns AS
            CAST(a.attnum AS sql_identifier) AS dtd_identifier,
            CAST('NO' AS yes_or_no) AS is_self_referencing,
 
-           CAST('NO' AS yes_or_no) AS is_identity,
-           CAST(null AS character_data) AS identity_generation,
-           CAST(null AS character_data) AS identity_start,
-           CAST(null AS character_data) AS identity_increment,
-           CAST(null AS character_data) AS identity_maximum,
-           CAST(null AS character_data) AS identity_minimum,
-           CAST(null AS yes_or_no) AS identity_cycle,
+           CAST(CASE WHEN a.attidentity IN ('a', 'd') THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_identity,
+           CAST(CASE a.attidentity WHEN 'a' THEN 'ALWAYS' WHEN 'd' THEN 'BY DEFAULT' END AS character_data) AS identity_generation,
+           CAST(p.start_value AS character_data) AS identity_start,
+           CAST(p.increment AS character_data) AS identity_increment,
+           CAST(p.maximum_value AS character_data) AS identity_maximum,
+           CAST(p.minimum_value AS character_data) AS identity_minimum,
+           CAST(CASE WHEN p.cycle_option THEN 'YES' ELSE 'NO' END AS yes_or_no) AS identity_cycle,
 
            CAST('NEVER' AS character_data) AS is_generated,
            CAST(null AS character_data) AS generation_expression,
@@ -750,6 +750,8 @@ CREATE VIEW columns AS
            ON (t.typtype = 'd' AND t.typbasetype = bt.oid)
          LEFT JOIN (pg_collation co JOIN pg_namespace nco ON (co.collnamespace = nco.oid))
            ON a.attcollation = co.oid AND (nco.nspname, co.collname) <> ('pg_catalog', 'default')
+         LEFT JOIN (pg_depend dep JOIN pg_class seq ON (dep.classid = 'pg_class'::regclass AND dep.objid = seq.oid AND dep.deptype = 'i') JOIN LATERAL pg_sequence_parameters(seq.oid) p ON true)
+           ON (dep.refclassid = 'pg_attrdef'::regclass AND dep.refobjid = ad.oid)
 
     WHERE (NOT pg_is_other_temp_schema(nc.oid))
 
@@ -1543,6 +1545,7 @@ CREATE VIEW sequences AS
     FROM pg_namespace nc, pg_class c, LATERAL pg_sequence_parameters(c.oid) p
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
+          AND NOT EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND deptype = 'i')
           AND (NOT pg_is_other_temp_schema(nc.oid))
           AND (pg_has_role(c.relowner, 'USAGE')
                OR has_sequence_privilege(c.oid, 'SELECT, UPDATE, USAGE') );
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 7a0713e..0823b88 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -19,6 +19,7 @@
 #include "access/htup_details.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
+#include "catalog/pg_attrdef.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_extension.h"
@@ -554,17 +555,20 @@ markSequenceUnowned(Oid seqId)
 {
 	deleteDependencyRecordsForClass(RelationRelationId, seqId,
 									RelationRelationId, DEPENDENCY_AUTO);
+	deleteDependencyRecordsForClass(RelationRelationId, seqId,
+									AttrDefaultRelationId, DEPENDENCY_INTERNAL);
 }
 
 /*
- * Collect a list of OIDs of all sequences owned by the specified relation.
+ * Collect a list of OIDs of all sequences owned by the specified relation,
+ * and column if specified.
  */
 List *
-getOwnedSequences(Oid relid)
+getOwnedSequences(Oid relid, AttrNumber attnum)
 {
 	List	   *result = NIL;
 	Relation	depRel;
-	ScanKeyData key[2];
+	ScanKeyData key[3];
 	SysScanDesc scan;
 	HeapTuple	tup;
 
@@ -578,9 +582,14 @@ getOwnedSequences(Oid relid)
 				Anum_pg_depend_refobjid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(relid));
+	if (attnum)
+		ScanKeyInit(&key[2],
+					Anum_pg_depend_refobjsubid,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(attnum));
 
 	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 2, key);
+							  NULL, attnum ? 3 : 2, key);
 
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index fc3a8ee..7c965c0 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -22,8 +22,10 @@
 #include "access/xloginsert.h"
 #include "access/xlogutils.h"
 #include "catalog/dependency.h"
+#include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
+#include "catalog/pg_attrdef.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/sequence.h"
@@ -36,6 +38,7 @@
 #include "storage/smgr.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/resowner.h"
 #include "utils/syscache.h"
@@ -95,9 +98,9 @@ static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
 static Form_pg_sequence read_seq_tuple(SeqTable elm, Relation rel,
 			   Buffer *buf, HeapTuple seqtuple);
 static void init_params(ParseState *pstate, List *options, bool isInit,
-			Form_pg_sequence new, List **owned_by);
+						Form_pg_sequence new, List **owned_by, DependencyType *deptype);
 static void do_setval(Oid relid, int64 next, bool iscalled);
-static void process_owned_by(Relation seqrel, List *owned_by);
+static void process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype);
 
 
 /*
@@ -109,6 +112,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 {
 	FormData_pg_sequence new;
 	List	   *owned_by;
+	DependencyType deptype;
 	CreateStmt *stmt = makeNode(CreateStmt);
 	Oid			seqoid;
 	ObjectAddress address;
@@ -145,7 +149,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	}
 
 	/* Check and set all option values */
-	init_params(pstate, seq->options, true, &new, &owned_by);
+	init_params(pstate, seq->options, true, &new, &owned_by, &deptype);
 
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
@@ -162,6 +166,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 		coldef->storage = 0;
 		coldef->raw_default = NULL;
 		coldef->cooked_default = NULL;
+		coldef->identity = ' ';
 		coldef->collClause = NULL;
 		coldef->collOid = InvalidOid;
 		coldef->constraints = NIL;
@@ -247,7 +252,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(rel, owned_by);
+		process_owned_by(rel, owned_by, deptype);
 
 	heap_close(rel, NoLock);
 
@@ -414,6 +419,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	Form_pg_sequence seq;
 	FormData_pg_sequence new;
 	List	   *owned_by;
+	DependencyType deptype;
 	ObjectAddress address;
 
 	/* Open and lock sequence. */
@@ -440,7 +446,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	memcpy(&new, seq, sizeof(FormData_pg_sequence));
 
 	/* Check and set new values */
-	init_params(pstate, stmt->options, false, &new, &owned_by);
+	init_params(pstate, stmt->options, false, &new, &owned_by, &deptype);
 
 	/* Clear local cache so that we don't think we have cached numbers */
 	/* Note that we do not change the currval() state */
@@ -483,7 +489,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(seqrel, owned_by);
+		process_owned_by(seqrel, owned_by, deptype);
 
 	InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
@@ -1164,7 +1170,7 @@ read_seq_tuple(SeqTable elm, Relation rel, Buffer *buf, HeapTuple seqtuple)
  */
 static void
 init_params(ParseState *pstate, List *options, bool isInit,
-			Form_pg_sequence new, List **owned_by)
+			Form_pg_sequence new, List **owned_by, DependencyType *deptype)
 {
 	DefElem    *start_value = NULL;
 	DefElem    *restart_value = NULL;
@@ -1173,9 +1179,11 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	DefElem    *min_value = NULL;
 	DefElem    *cache_value = NULL;
 	DefElem    *is_cycled = NULL;
+	DefElem	   *deptype_el = NULL;
 	ListCell   *option;
 
 	*owned_by = NIL;
+	*deptype = DEPENDENCY_AUTO;
 
 	foreach(option, options)
 	{
@@ -1253,6 +1261,15 @@ init_params(ParseState *pstate, List *options, bool isInit,
 						 parser_errposition(pstate, defel->location)));
 			*owned_by = defGetQualifiedName(defel);
 		}
+		else if (strcmp(defel->defname, "deptype") == 0)
+		{
+			if (deptype_el)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			deptype_el = defel;
+			*deptype = intVal(deptype_el->arg);
+		}
 		else
 			elog(ERROR, "option \"%s\" not recognized",
 				 defel->defname);
@@ -1431,6 +1448,38 @@ init_params(ParseState *pstate, List *options, bool isInit,
 		new->cache_value = 1;
 }
 
+static Oid
+get_attrdef_oid(Oid relid, AttrNumber attnum)
+{
+	Relation    attrdef_rel;
+	ScanKeyData scankeys[2];
+	SysScanDesc scan;
+	HeapTuple   tuple;
+	Oid			result = InvalidOid;
+
+	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
+
+	ScanKeyInit(&scankeys[0],
+				Anum_pg_attrdef_adrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(relid));
+	ScanKeyInit(&scankeys[1],
+				Anum_pg_attrdef_adnum,
+				BTEqualStrategyNumber, F_INT2EQ,
+				Int16GetDatum(attnum));
+
+	scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
+							  NULL, 2, scankeys);
+
+	if (HeapTupleIsValid(tuple = systable_getnext(scan)))
+		result = HeapTupleGetOid(tuple);
+
+	systable_endscan(scan);
+	heap_close(attrdef_rel, RowExclusiveLock);
+
+	return result;
+}
+
 /*
  * Process an OWNED BY option for CREATE/ALTER SEQUENCE
  *
@@ -1440,7 +1489,7 @@ init_params(ParseState *pstate, List *options, bool isInit,
  * as the sequence.
  */
 static void
-process_owned_by(Relation seqrel, List *owned_by)
+process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype)
 {
 	int			nnames;
 	Relation	tablerel;
@@ -1518,6 +1567,20 @@ process_owned_by(Relation seqrel, List *owned_by)
 		depobject.objectId = RelationGetRelid(seqrel);
 		depobject.objectSubId = 0;
 		recordDependencyOn(&depobject, &refobject, DEPENDENCY_AUTO);
+
+		/*
+		 * For identity columns, also record an internal dependency of the
+		 * sequence on the default (you drop the default, the sequence is
+		 * removed).  We still do the auto dependency on the column, because
+		 * that is what TRUNCATE RESTART IDENTITY looks for.
+		 */
+		if (deptype == DEPENDENCY_INTERNAL)
+		{
+			refobject.classId = AttrDefaultRelationId;
+			refobject.objectId = get_attrdef_oid(RelationGetRelid(tablerel), attnum);
+			refobject.objectSubId = 0;
+			recordDependencyOn(&depobject, &refobject, DEPENDENCY_INTERNAL);
+		}
 	}
 
 	/* Done, but hold lock until commit */
@@ -1527,6 +1590,35 @@ process_owned_by(Relation seqrel, List *owned_by)
 
 
 /*
+ * Return sequence parameters in a list of the form created by the parser.
+ */
+List *
+sequence_options(Oid relid)
+{
+	SeqTable	elm;
+	Relation	seqrel;
+	Buffer		buf;
+	HeapTupleData seqtuple;
+	Form_pg_sequence seq;
+	List	   *options = NIL;
+
+	init_sequence(relid, &elm, &seqrel);
+	seq = read_seq_tuple(elm, seqrel, &buf, &seqtuple);
+
+	options = lappend(options, makeDefElem("cache", (Node *) makeInteger(seq->cache_value), -1));
+	options = lappend(options, makeDefElem("cycle", (Node *) makeInteger(seq->is_cycled), -1));
+	options = lappend(options, makeDefElem("increment", (Node *) makeInteger(seq->increment_by), -1));
+	options = lappend(options, makeDefElem("maxvalue", (Node *) makeInteger(seq->max_value), -1));
+	options = lappend(options, makeDefElem("minvalue", (Node *) makeInteger(seq->min_value), -1));
+	options = lappend(options, makeDefElem("start", (Node *) makeInteger(seq->start_value), -1));
+
+	UnlockReleaseBuffer(buf);
+	relation_close(seqrel, NoLock);
+
+	return options;
+}
+
+/*
  * Return sequence parameters, for use by information schema
  */
 Datum
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2137372..b99e59b 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -344,6 +344,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@@ -650,6 +655,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1113,7 +1121,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;
 
 			foreach(seqcell, seqlist)
@@ -1663,6 +1671,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def->storage = attribute->attstorage;
 				def->raw_default = NULL;
 				def->cooked_default = NULL;
+				def->identity = attribute->attidentity;
 				def->collClause = NULL;
 				def->collOid = attribute->attcollation;
 				def->constraints = NIL;
@@ -1851,6 +1860,13 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   get_collation_name(newcollid))));
 
+				if (def->identity != ' ' && newdef->identity != ' ')
+					ereport(ERROR,
+							(errcode(ERRCODE_DATATYPE_MISMATCH),
+							 errmsg("column \"%s\" has conflicting identity definitions",
+									attributeName)));
+				def->identity = newdef->identity;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@@ -2941,6 +2957,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -3154,6 +3173,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_ADD_COL;
 			break;
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
+		case AT_AddIdentity:
+		case AT_DropIdentity:
 
 			/*
 			 * We allow defaults on views so that INSERT into a view can have
@@ -3166,6 +3187,11 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode);
@@ -3476,6 +3502,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@@ -4850,6 +4885,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = ' ';
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@@ -5159,6 +5195,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		cdef->is_local = true;
 		cdef->is_not_null = true;
 		cdef->storage = 0;
+		cdef->identity = ' ';
 		cdef->location = -1;
 		cmd->def = (Node *) cdef;
 	}
@@ -5370,6 +5407,12 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@@ -5405,6 +5448,206 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	RawColumnDefault *rawEnt;
+	ObjectAddress address;
+	ColumnDef  *cdef = (ColumnDef *) def;
+
+	Assert(IsA(def, ColumnDef));
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity != ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	simple_heap_update(attrelation, &tuple->t_self, tuple);
+	CatalogUpdateIndexes(attrelation, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	CommandCounterIncrement();
+
+	rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
+	rawEnt->attnum = attnum;
+	rawEnt->raw_default = cdef->raw_default;
+
+	AddRelationNewConstraints(rel, list_make1(rawEnt), NIL,
+							  false, true, false);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, (List *) def)
+	{
+		DefElem	   *defel = (DefElem *) lfirst(option);
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		simple_heap_update(attrelation, &tuple->t_self, tuple);
+		CatalogUpdateIndexes(attrelation, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = ' ';
+	simple_heap_update(attrelation, &tuple->t_self, tuple);
+	CatalogUpdateIndexes(attrelation, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	CommandCounterIncrement();
+
+	RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false,
+					  true);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET STATISTICS
  */
 static void
@@ -7913,6 +8156,14 @@ ATPrepAlterColumnType(List **wqueue,
 				 errmsg("cannot alter inherited column \"%s\"",
 						colName)));
 
+	/* Don't alter identity columns.  (XXX This could be done, but needs more
+	 * work to check permitted types, adjust sequence.) */
+	if (attTup->attidentity != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot alter data type of identity column \"%s\"",
+						colName)));
+
 	/* Look up the target type */
 	typenameTypeIdAndMod(NULL, typeName, &targettype, &targettypmod);
 
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 71714bc..73392b0 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2624,6 +2624,7 @@ _copyColumnDef(const ColumnDef *from)
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_SCALAR_FIELD(identity);
 	COPY_NODE_FIELD(collClause);
 	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
@@ -2646,6 +2647,7 @@ _copyConstraint(const Constraint *from)
 	COPY_SCALAR_FIELD(is_no_inherit);
 	COPY_NODE_FIELD(raw_expr);
 	COPY_STRING_FIELD(cooked_expr);
+	COPY_SCALAR_FIELD(generated_when);
 	COPY_NODE_FIELD(keys);
 	COPY_NODE_FIELD(exclusions);
 	COPY_NODE_FIELD(options);
@@ -2742,6 +2744,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
 	COPY_NODE_FIELD(targetList);
+	COPY_SCALAR_FIELD(override);
 	COPY_NODE_FIELD(onConflict);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(groupClause);
@@ -2771,6 +2774,7 @@ _copyInsertStmt(const InsertStmt *from)
 	COPY_NODE_FIELD(onConflictClause);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(withClause);
+	COPY_SCALAR_FIELD(override);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 29a090f..0bee88e 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -932,6 +932,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
 	COMPARE_NODE_FIELD(targetList);
+	COMPARE_SCALAR_FIELD(override);
 	COMPARE_NODE_FIELD(onConflict);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(groupClause);
@@ -959,6 +960,7 @@ _equalInsertStmt(const InsertStmt *a, const InsertStmt *b)
 	COMPARE_NODE_FIELD(onConflictClause);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(withClause);
+	COMPARE_SCALAR_FIELD(override);
 
 	return true;
 }
@@ -2378,6 +2380,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_SCALAR_FIELD(identity);
 	COMPARE_NODE_FIELD(collClause);
 	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
@@ -2398,6 +2401,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_SCALAR_FIELD(is_no_inherit);
 	COMPARE_NODE_FIELD(raw_expr);
 	COMPARE_STRING_FIELD(cooked_expr);
+	COMPARE_SCALAR_FIELD(generated_when);
 	COMPARE_NODE_FIELD(keys);
 	COMPARE_NODE_FIELD(exclusions);
 	COMPARE_NODE_FIELD(options);
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index 20e2dbd..08bd23a 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -497,6 +497,7 @@ makeColumnDef(const char *colname, Oid typeOid, int32 typmod, Oid collOid)
 	n->storage = 0;
 	n->raw_default = NULL;
 	n->cooked_default = NULL;
+	n->identity = ' ';
 	n->collClause = NULL;
 	n->collOid = collOid;
 	n->constraints = NIL;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index ae86954..a2b3818 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2575,6 +2575,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_CHAR_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_CHAR_FIELD(identity);
 	WRITE_NODE_FIELD(collClause);
 	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
@@ -2680,6 +2681,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
 	WRITE_NODE_FIELD(targetList);
+	WRITE_ENUM_FIELD(override, OverridingKind);
 	WRITE_NODE_FIELD(onConflict);
 	WRITE_NODE_FIELD(returningList);
 	WRITE_NODE_FIELD(groupClause);
@@ -3174,6 +3176,13 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_STRING_FIELD(cooked_expr);
 			break;
 
+		case CONSTR_IDENTITY:
+			appendStringInfoString(str, "IDENTITY");
+			WRITE_NODE_FIELD(raw_expr);
+			WRITE_STRING_FIELD(cooked_expr);
+			WRITE_CHAR_FIELD(generated_when);
+			break;
+
 		case CONSTR_CHECK:
 			appendStringInfoString(str, "CHECK");
 			WRITE_BOOL_FIELD(is_no_inherit);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 917e6c8..163699c 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -249,6 +249,7 @@ _readQuery(void)
 	READ_NODE_FIELD(rtable);
 	READ_NODE_FIELD(jointree);
 	READ_NODE_FIELD(targetList);
+	READ_ENUM_FIELD(override, OverridingKind);
 	READ_NODE_FIELD(onConflict);
 	READ_NODE_FIELD(returningList);
 	READ_NODE_FIELD(groupClause);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 6901e08..fc59260 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -464,6 +464,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
 	}
 
+	qry->override = stmt->override;
+
 	isOnConflictUpdate = (stmt->onConflictClause &&
 						stmt->onConflictClause->action == ONCONFLICT_UPDATE);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5547fc8..b6a4026 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -278,6 +278,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity
 %type <list>	alter_table_cmds alter_type_cmds
+%type <list>    alter_identity_column_option_list
+%type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -424,7 +426,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				select_offset_value2 opt_select_fetch_first_value
 %type <ival>	row_or_rows first_or_next
 
-%type <list>	OptSeqOptList SeqOptList
+%type <list>	OptSeqOptList SeqOptList OptParenthesizedSeqOptList
 %type <defelt>	SeqOptElem
 
 %type <istmt>	insert_rest
@@ -541,6 +543,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_frame_clause frame_extent frame_bound
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
+%type <ival>	generated_when override_kind
 
 /*
  * Non-keyword token types.  These are hard-wired into the "flex" lexer.
@@ -591,7 +594,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
 	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
-	GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
+	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
 
 	HANDLER HAVING HEADER_P HOLD HOUR_P
 
@@ -615,7 +618,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	NULLS_P NUMERIC
 
 	OBJECT_P OF OFF OFFSET OIDS ON ONLY OPERATOR OPTION OPTIONS OR
-	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
+	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
 	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
@@ -2026,6 +2029,40 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
+			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					Constraint *c = makeNode(Constraint);
+
+					c->contype = CONSTR_IDENTITY;
+					c->generated_when = $6;
+					c->options = $9;
+					c->location = @5;
+
+					n->subtype = AT_AddIdentity;
+					n->name = $3;
+					n->def = (Node *) c;
+
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
+			| ALTER opt_column ColId alter_identity_column_option_list
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->def = (Node *) $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
+			| ALTER opt_column ColId DROP IDENTITY_P
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
@@ -2463,6 +2500,38 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_option_list:
+			alter_identity_column_option
+				{ $$ = list_make1($1); }
+			| alter_identity_column_option_list alter_identity_column_option
+				{ $$ = lappend($1, $2); }
+		;
+
+alter_identity_column_option:
+			RESTART
+				{
+					$$ = makeDefElem("restart", NULL, @1);
+				}
+			| RESTART opt_with NumericOnly
+				{
+					$$ = makeDefElem("restart", (Node *)$3, @1);
+				}
+			| SET SeqOptElem
+				{
+					if (strcmp($2->defname, "restart") == 0 ||
+						strcmp($2->defname, "owned_by") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("sequence option \"%s\" not supported here", $2->defname),
+								 parser_errposition(@2)));
+					$$ = $2;
+				}
+			| SET GENERATED generated_when
+				{
+					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
+				}
+		;
+
 
 /*****************************************************************************
  *
@@ -2964,6 +3033,7 @@ columnDef:	ColId Typename create_generic_options ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					n->fdwoptions = $3;
 					SplitColQualList($4, &n->constraints, &n->collClause,
@@ -2985,6 +3055,7 @@ columnOptions:	ColId WITH OPTIONS ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					SplitColQualList($4, &n->constraints, &n->collClause,
 									 yyscanner);
@@ -3097,6 +3168,15 @@ ColConstraintElem:
 					n->cooked_expr = NULL;
 					$$ = (Node *)n;
 				}
+			| GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					Constraint *n = makeNode(Constraint);
+					n->contype = CONSTR_IDENTITY;
+					n->generated_when = $2;
+					n->options = $5;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
 			| REFERENCES qualified_name opt_column_list key_match key_actions
 				{
 					Constraint *n = makeNode(Constraint);
@@ -3114,6 +3194,11 @@ ColConstraintElem:
 				}
 		;
 
+generated_when:
+			ALWAYS			{ $$ = CONSTR_GENERATED_ALWAYS; }
+			| BY DEFAULT	{ $$ = CONSTR_GENERATED_DEFAULT; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -3180,6 +3265,7 @@ TableLikeOptionList:
 TableLikeOption:
 				DEFAULTS			{ $$ = CREATE_TABLE_LIKE_DEFAULTS; }
 				| CONSTRAINTS		{ $$ = CREATE_TABLE_LIKE_CONSTRAINTS; }
+				| IDENTITY_P		{ $$ = CREATE_TABLE_LIKE_IDENTITY; }
 				| INDEXES			{ $$ = CREATE_TABLE_LIKE_INDEXES; }
 				| STORAGE			{ $$ = CREATE_TABLE_LIKE_STORAGE; }
 				| COMMENTS			{ $$ = CREATE_TABLE_LIKE_COMMENTS; }
@@ -3630,6 +3716,10 @@ OptSeqOptList: SeqOptList							{ $$ = $1; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+OptParenthesizedSeqOptList: '(' SeqOptList ')'		{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
@@ -3670,6 +3760,11 @@ SeqOptElem: CACHE NumericOnly
 				{
 					$$ = makeDefElem("owned_by", (Node *)$3, @1);
 				}
+			| SEQUENCE NAME_P any_name
+				{
+					/* not documented, only used by pg_dump */
+					$$ = makeDefElem("sequence_name", (Node *)$3, @1);
+				}
 			| START opt_with NumericOnly
 				{
 					$$ = makeDefElem("start", (Node *)$3, @1);
@@ -9678,12 +9773,26 @@ insert_rest:
 					$$->cols = NIL;
 					$$->selectStmt = $1;
 				}
+			| OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = NIL;
+					$$->override = $2;
+					$$->selectStmt = $4;
+				}
 			| '(' insert_column_list ')' SelectStmt
 				{
 					$$ = makeNode(InsertStmt);
 					$$->cols = $2;
 					$$->selectStmt = $4;
 				}
+			| '(' insert_column_list ')' OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = $2;
+					$$->override = $5;
+					$$->selectStmt = $7;
+				}
 			| DEFAULT VALUES
 				{
 					$$ = makeNode(InsertStmt);
@@ -9692,6 +9801,11 @@ insert_rest:
 				}
 		;
 
+override_kind:
+			USER		{ $$ = OVERRIDING_USER_VALUE; }
+			| SYSTEM_P	{ $$ = OVERRIDING_SYSTEM_VALUE; }
+		;
+
 insert_column_list:
 			insert_column_item
 					{ $$ = list_make1($1); }
@@ -11088,6 +11202,7 @@ TableFuncElement:	ColId Typename opt_collate_clause
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collClause = (CollateClause *) $3;
 					n->collOid = InvalidOid;
 					n->constraints = NIL;
@@ -13825,6 +13940,7 @@ unreserved_keyword:
 			| OPTIONS
 			| ORDINALITY
 			| OVER
+			| OVERRIDING
 			| OWNED
 			| OWNER
 			| PARALLEL
@@ -14083,6 +14199,7 @@ reserved_keyword:
 			| FOR
 			| FOREIGN
 			| FROM
+			| GENERATED
 			| GRANT
 			| GROUP_P
 			| HAVING
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 0670bc2..41f0c69 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -42,6 +42,7 @@
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
@@ -343,6 +344,150 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	return result;
 }
 
+static void
+generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column, List *seqoptions, DependencyType deptype,
+						 char **snamespace_p, char **sname_p)
+{
+	ListCell   *option;
+	DefElem	   *nameEl = NULL;
+	Oid			snamespaceid;
+	char	   *snamespace;
+	char	   *sname;
+	CreateSeqStmt *seqstmt;
+	AlterSeqStmt *altseqstmt;
+	List	   *attnamelist;
+
+	/*
+	 * Determine namespace and name to use for the sequence.
+	 *
+	 * First, check if a sequence name was passed in as an option.  This is
+	 * used by pg_dump.  Else, generate a name.
+	 *
+	 * Although we use ChooseRelationName, it's not guaranteed that the
+	 * selected sequence name won't conflict; given sufficiently long
+	 * field names, two different serial columns in the same table could
+	 * be assigned the same sequence name, and we'd not notice since we
+	 * aren't creating the sequence quite yet.  In practice this seems
+	 * quite unlikely to be a problem, especially since few people would
+	 * need two serial columns in one table.
+	 */
+
+	foreach(option, seqoptions)
+	{
+		DefElem    *defel = (DefElem *) lfirst(option);
+
+		if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			if (nameEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			nameEl = defel;
+		}
+	}
+
+	if (nameEl)
+	{
+		RangeVar *rv = makeRangeVarFromNameList((List *) nameEl->arg);
+		snamespace = rv->schemaname;
+		sname = rv->relname;
+		list_delete_ptr(seqoptions, nameEl);
+	}
+	else
+	{
+		if (cxt->rel)
+			snamespaceid = RelationGetNamespace(cxt->rel);
+		else
+		{
+			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
+			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
+		}
+		snamespace = get_namespace_name(snamespaceid);
+		sname = ChooseRelationName(cxt->relation->relname,
+								   column->colname,
+								   "seq",
+								   snamespaceid);
+	}
+
+	ereport(DEBUG1,
+			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
+					cxt->stmtType, sname,
+					cxt->relation->relname, column->colname)));
+
+	/*
+	 * Build a CREATE SEQUENCE command to create the sequence object, and
+	 * add it to the list of things to be done before this CREATE/ALTER
+	 * TABLE.
+	 */
+	seqstmt = makeNode(CreateSeqStmt);
+	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->options = seqoptions;
+
+	/*
+	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
+	 * by the table's owner.  The current user might be someone else
+	 * (perhaps a superuser, or someone who's only a member of the owning
+	 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
+	 * and sequence have exactly the same owning role.
+	 */
+	if (cxt->rel)
+		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
+	else
+		seqstmt->ownerId = InvalidOid;
+
+	cxt->blist = lappend(cxt->blist, seqstmt);
+
+	/*
+	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
+	 * as owned by this column, and add it to the list of things to be
+	 * done after this CREATE/ALTER TABLE.
+	 */
+	altseqstmt = makeNode(AlterSeqStmt);
+	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	attnamelist = list_make3(makeString(snamespace),
+							 makeString(cxt->relation->relname),
+							 makeString(column->colname));
+	altseqstmt->options = list_make2(makeDefElem("owned_by",
+												 (Node *) attnamelist, -1),
+									 makeDefElem("deptype",
+												 (Node *) makeInteger(deptype), -1));
+
+	cxt->alist = lappend(cxt->alist, altseqstmt);
+
+	*snamespace_p = snamespace;
+	*sname_p = sname;
+}
+
+/*
+ * Create an expression tree representing the function call
+ * nextval('sequencename').  We cannot reduce the raw tree to cooked
+ * form until after the sequence is created, but there's no need to do
+ * so.
+ */
+static FuncCall *
+generateNextvalExpr(char *snamespace, char *sname)
+{
+	char	   *qstring;
+	A_Const    *snamenode;
+	TypeCast   *castnode;
+	FuncCall   *funccallnode;
+
+	qstring = quote_qualified_identifier(snamespace, sname);
+	snamenode = makeNode(A_Const);
+	snamenode->val.type = T_String;
+	snamenode->val.val.str = qstring;
+	snamenode->location = -1;
+	castnode = makeNode(TypeCast);
+	castnode->typeName = SystemTypeName("regclass");
+	castnode->arg = (Node *) snamenode;
+	castnode->location = -1;
+	funccallnode = makeFuncCall(SystemFuncName("nextval"),
+								list_make1(castnode),
+								-1);
+
+	return funccallnode;
+}
+
 /*
  * transformColumnDefinition -
  *		transform a single ColumnDef within CREATE TABLE
@@ -354,7 +499,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	bool		is_serial;
 	bool		saw_nullable;
 	bool		saw_default;
-	Constraint *constraint;
+	bool		saw_identity;
 	ListCell   *clist;
 
 	cxt->columns = lappend(cxt->columns, column);
@@ -409,110 +554,21 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	/* Special actions for SERIAL pseudo-types */
 	if (is_serial)
 	{
-		Oid			snamespaceid;
 		char	   *snamespace;
 		char	   *sname;
-		char	   *qstring;
-		A_Const    *snamenode;
-		TypeCast   *castnode;
-		FuncCall   *funccallnode;
-		CreateSeqStmt *seqstmt;
-		AlterSeqStmt *altseqstmt;
-		List	   *attnamelist;
-
-		/*
-		 * Determine namespace and name to use for the sequence.
-		 *
-		 * Although we use ChooseRelationName, it's not guaranteed that the
-		 * selected sequence name won't conflict; given sufficiently long
-		 * field names, two different serial columns in the same table could
-		 * be assigned the same sequence name, and we'd not notice since we
-		 * aren't creating the sequence quite yet.  In practice this seems
-		 * quite unlikely to be a problem, especially since few people would
-		 * need two serial columns in one table.
-		 */
-		if (cxt->rel)
-			snamespaceid = RelationGetNamespace(cxt->rel);
-		else
-		{
-			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
-			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
-		}
-		snamespace = get_namespace_name(snamespaceid);
-		sname = ChooseRelationName(cxt->relation->relname,
-								   column->colname,
-								   "seq",
-								   snamespaceid);
-
-		ereport(DEBUG1,
-				(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
-						cxt->stmtType, sname,
-						cxt->relation->relname, column->colname)));
-
-		/*
-		 * Build a CREATE SEQUENCE command to create the sequence object, and
-		 * add it to the list of things to be done before this CREATE/ALTER
-		 * TABLE.
-		 */
-		seqstmt = makeNode(CreateSeqStmt);
-		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = NIL;
-
-		/*
-		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
-		 * by the table's owner.  The current user might be someone else
-		 * (perhaps a superuser, or someone who's only a member of the owning
-		 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
-		 * and sequence have exactly the same owning role.
-		 */
-		if (cxt->rel)
-			seqstmt->ownerId = cxt->rel->rd_rel->relowner;
-		else
-			seqstmt->ownerId = InvalidOid;
-
-		cxt->blist = lappend(cxt->blist, seqstmt);
-
-		/*
-		 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
-		 * as owned by this column, and add it to the list of things to be
-		 * done after this CREATE/ALTER TABLE.
-		 */
-		altseqstmt = makeNode(AlterSeqStmt);
-		altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		attnamelist = list_make3(makeString(snamespace),
-								 makeString(cxt->relation->relname),
-								 makeString(column->colname));
-		altseqstmt->options = list_make1(makeDefElem("owned_by",
-												  (Node *) attnamelist, -1));
+		Constraint *constraint;
 
-		cxt->alist = lappend(cxt->alist, altseqstmt);
+		generateSerialExtraStmts(cxt, column, NIL, DEPENDENCY_AUTO, &snamespace, &sname);
 
 		/*
 		 * Create appropriate constraints for SERIAL.  We do this in full,
 		 * rather than shortcutting, so that we will detect any conflicting
 		 * constraints the user wrote (like a different DEFAULT).
-		 *
-		 * Create an expression tree representing the function call
-		 * nextval('sequencename').  We cannot reduce the raw tree to cooked
-		 * form until after the sequence is created, but there's no need to do
-		 * so.
 		 */
-		qstring = quote_qualified_identifier(snamespace, sname);
-		snamenode = makeNode(A_Const);
-		snamenode->val.type = T_String;
-		snamenode->val.val.str = qstring;
-		snamenode->location = -1;
-		castnode = makeNode(TypeCast);
-		castnode->typeName = SystemTypeName("regclass");
-		castnode->arg = (Node *) snamenode;
-		castnode->location = -1;
-		funccallnode = makeFuncCall(SystemFuncName("nextval"),
-									list_make1(castnode),
-									-1);
 		constraint = makeNode(Constraint);
 		constraint->contype = CONSTR_DEFAULT;
 		constraint->location = -1;
-		constraint->raw_expr = (Node *) funccallnode;
+		constraint->raw_expr = (Node *) generateNextvalExpr(snamespace, sname);
 		constraint->cooked_expr = NULL;
 		column->constraints = lappend(column->constraints, constraint);
 
@@ -527,9 +583,12 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
 	saw_nullable = false;
 	saw_default = false;
+	saw_identity = false;
 
 	foreach(clist, column->constraints)
 	{
+		Constraint *constraint;
+
 		constraint = lfirst(clist);
 		Assert(IsA(constraint, Constraint));
 
@@ -569,9 +628,43 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 												constraint->location)));
 				column->raw_default = constraint->raw_expr;
 				Assert(constraint->cooked_expr == NULL);
+				column->identity = ' ';
 				saw_default = true;
 				break;
 
+			case CONSTR_IDENTITY:
+			{
+				char	   *snamespace;
+				char	   *sname;
+				Type		ctype;
+				Oid			typeOid;
+
+				ctype = typenameType(cxt->pstate, column->typeName, NULL);
+				typeOid = HeapTupleGetOid(ctype);
+				ReleaseSysCache(ctype);
+
+				if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("identity column type must be smallint, integer, or bigint")));
+
+				if (saw_identity)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
+									column->colname, cxt->relation->relname),
+							 parser_errposition(cxt->pstate,
+												constraint->location)));
+
+				generateSerialExtraStmts(cxt, column, constraint->options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+				column->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+				Assert(constraint->cooked_expr == NULL);
+				column->identity = constraint->generated_when;
+				saw_identity = true;
+				column->is_not_null = TRUE;
+				break;
+			}
+
 			case CONSTR_CHECK:
 				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
 				break;
@@ -630,6 +723,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 					 constraint->contype);
 				break;
 		}
+
+		if (saw_default && saw_identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
+							column->colname, cxt->relation->relname),
+					 parser_errposition(cxt->pstate,
+										constraint->location)));
 	}
 
 	/*
@@ -834,6 +935,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		def->storage = 0;
 		def->raw_default = NULL;
 		def->cooked_default = NULL;
+		def->identity = ' ';
 		def->collClause = NULL;
 		def->collOid = attribute->attcollation;
 		def->constraints = NIL;
@@ -849,7 +951,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		/*
 		 * Copy default, if present and the default has been requested
 		 */
-		if (attribute->atthasdef &&
+		if (attribute->atthasdef && attribute->attidentity == ' ' &&
 			(table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS))
 		{
 			Node	   *this_default = NULL;
@@ -877,6 +979,30 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			def->cooked_default = this_default;
 		}
 
+		/*
+		 * Copy identity if requested
+		 */
+		if (attribute->attidentity != ' ' &&
+			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
+		{
+			List       *seqlist;
+			Oid         seq_relid;
+			List	   *seq_options;
+			char	   *snamespace;
+			char	   *sname;
+
+			/*
+			 * find sequence owned by old column; extract sequence parameters;
+			 * build new default and create sequence commands
+			 */
+			seqlist = getOwnedSequences(RelationGetRelid(relation), attribute->attnum);
+			seq_relid = linitial_oid(seqlist);
+			seq_options = sequence_options(seq_relid);
+			generateSerialExtraStmts(cxt, def, seq_options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+			def->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+			def->identity = attribute->attidentity;
+		}
+
 		/* Likewise, copy storage if requested */
 		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
 			def->storage = attribute->attstorage;
@@ -1053,6 +1179,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 		n->storage = 0;
 		n->raw_default = NULL;
 		n->cooked_default = NULL;
+		n->identity = ' ';
 		n->collClause = NULL;
 		n->collOid = attr->attcollation;
 		n->constraints = NIL;
@@ -2594,6 +2721,87 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 					break;
 				}
 
+			case AT_AddIdentity:
+				{
+					Constraint  *def = (Constraint *) cmd->def;
+					ColumnDef *newdef = makeNode(ColumnDef);
+					Oid			typeOid;
+					char	   *snamespace;
+					char	   *sname;
+
+					Assert(IsA(def, Constraint));
+
+					typeOid = get_atttype(relid, get_attnum(relid, cmd->name));
+					if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("identity column type must be smallint, integer, or bigint")));
+
+					newdef->colname = cmd->name;  // XXX before below FIXME
+					generateSerialExtraStmts(&cxt, newdef, def->options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+					newdef->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+					newdef->identity = def->generated_when;
+
+					cmd->def = (Node *) newdef;
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_SetIdentity:
+				{
+					/*
+					 * Create an ALTER SEQUENCE statement for the internal
+					 * sequence of the identity column.
+					 */
+					ListCell   *lc;
+					List	   *newseqopts = NIL;
+					List	   *newdef = NIL;
+					List	   *seqlist;
+					AttrNumber	attnum;
+
+					/*
+					 * Split options into those handled by ALTER SEQUENCE and
+					 * those for ALTER TABLE proper.
+					 */
+					foreach(lc, (List *) cmd->def)
+					{
+						DefElem	   *def = (DefElem *) lfirst(lc);
+
+						if (strcmp(def->defname, "generated") == 0)
+							newdef = lappend(newdef, def);
+						else
+							newseqopts = lappend(newseqopts, def);
+					}
+
+					attnum = get_attnum(relid, cmd->name);
+
+					if (attnum)
+					{
+						seqlist = getOwnedSequences(relid, attnum);
+						if (seqlist)
+						{
+							AlterSeqStmt *seqstmt;
+							Oid			seq_relid;
+
+							seqstmt = makeNode(AlterSeqStmt);
+							seq_relid = linitial_oid(seqlist);
+							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															 get_rel_name(seq_relid), -1);
+							seqstmt->options = newseqopts;
+							seqstmt->missing_ok = false;
+
+							cxt.alist = lappend(cxt.alist, seqstmt);
+						}
+					}
+					/* If column was not found or did not own sequences, we
+					 * just let the ALTER TABLE command error out. */
+
+					cmd->def = (Node *) newdef;
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
 			default:
 				newcmds = lappend(newcmds, cmd);
 				break;
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index b828e3c..58364e5 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -61,6 +61,7 @@ static Query *rewriteRuleAction(Query *parsetree,
 static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static List *rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+								 OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list);
@@ -696,6 +697,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 static List *
 rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list)
@@ -776,6 +778,7 @@ rewriteTargetListIU(List *targetList,
 	for (attrno = 1; attrno <= numattrs; attrno++)
 	{
 		TargetEntry *new_tle = new_tles[attrno - 1];
+		bool	apply_default;
 
 		att_tup = target_relation->rd_att->attrs[attrno - 1];
 
@@ -788,8 +791,37 @@ rewriteTargetListIU(List *targetList,
 		 * it's an INSERT and there's no tlist entry for the column, or the
 		 * tlist entry is a DEFAULT placeholder node.
 		 */
-		if ((new_tle == NULL && commandType == CMD_INSERT) ||
-			(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
+		apply_default =((new_tle == NULL && commandType == CMD_INSERT) ||
+						(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
+
+		if (commandType == CMD_INSERT)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+			{
+				if (override != OVERRIDING_SYSTEM_VALUE)
+					ereport(ERROR,
+							(errcode(ERRCODE_GENERATED_ALWAYS),
+							 errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
+							 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+									   NameStr(att_tup->attname)),
+							 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
+			}
+
+			if (att_tup->attidentity == CONSTR_GENERATED_DEFAULT && override == OVERRIDING_USER_VALUE)
+				apply_default = true;
+		}
+
+		if (commandType == CMD_UPDATE)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+				ereport(ERROR,
+						(errcode(ERRCODE_GENERATED_ALWAYS),
+						 errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
+						 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+								   NameStr(att_tup->attname))));
+		}
+
+		if (apply_default)
 		{
 			Node	   *new_expr;
 
@@ -3214,6 +3246,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				/* Process the main targetlist ... */
 				parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
 													  parsetree->commandType,
+															parsetree->override,
 															rt_entry_relation,
 												   parsetree->resultRelation,
 															&attrnos);
@@ -3226,6 +3259,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->targetList =
 					rewriteTargetListIU(parsetree->targetList,
 										parsetree->commandType,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation, NULL);
 			}
@@ -3236,6 +3270,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->onConflict->onConflictSet =
 					rewriteTargetListIU(parsetree->onConflict->onConflictSet,
 										CMD_UPDATE,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation,
 										NULL);
@@ -3245,7 +3280,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 		{
 			parsetree->targetList =
 				rewriteTargetListIU(parsetree->targetList,
-									parsetree->commandType, rt_entry_relation,
+									parsetree->commandType,
+									parsetree->override,
+									rt_entry_relation,
 									parsetree->resultRelation, NULL);
 			rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
 		}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 8a81d7a..fb3aa78 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5605,6 +5605,14 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (query->targetList)
 		appendStringInfoString(buf, ") ");
 
+	if (query->override)
+	{
+		if (query->override == OVERRIDING_SYSTEM_VALUE)
+			appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
+		else if (query->override == OVERRIDING_USER_VALUE)
+			appendStringInfoString(buf, "OVERRIDING USER VALUE ");
+	}
+
 	if (select_rte)
 	{
 		/* Add the SELECT */
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 13ae6ad..2d7cdaa 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -836,6 +836,27 @@ get_attnum(Oid relid, const char *attname)
 		return InvalidAttrNumber;
 }
 
+char
+get_attidentity(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		char			result;
+
+		result = att_tup->attidentity;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return 0;
+}
+
 /*
  * get_atttype
  *
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 79e0b1f..45ab961 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -2929,6 +2929,7 @@ RelationBuildLocalRelation(const char *relname,
 	has_not_null = false;
 	for (i = 0; i < natts; i++)
 	{
+		rel->rd_att->attrs[i]->attidentity = tupDesc->attrs[i]->attidentity;
 		rel->rd_att->attrs[i]->attnotnull = tupDesc->attrs[i]->attnotnull;
 		has_not_null |= tupDesc->attrs[i]->attnotnull;
 	}
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index e7bdb92..2c5915b 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -326,6 +326,7 @@ Section: Class 42 - Syntax Error or Access Rule Violation
 42P21    E    ERRCODE_COLLATION_MISMATCH                                     collation_mismatch
 42P22    E    ERRCODE_INDETERMINATE_COLLATION                                indeterminate_collation
 42809    E    ERRCODE_WRONG_OBJECT_TYPE                                      wrong_object_type
+428C9    E    ERRCODE_GENERATED_ALWAYS                                       generated_always
 
 # Note: for ERRCODE purposes, we divide namable objects into these categories:
 # databases, schemas, prepared statements, cursors, tables, columns,
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 4da297f..fd90827 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1840,6 +1840,9 @@ dumpTableData_insert(Archive *fout, void *dcontext)
 						appendPQExpBufferStr(insertStmt, ") ");
 					}
 
+					if (tbinfo->needs_override)
+						appendPQExpBufferStr(insertStmt, "OVERRIDING SYSTEM VALUE ");
+
 					appendPQExpBufferStr(insertStmt, "VALUES (");
 				}
 			}
@@ -4848,6 +4851,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_toastreloptions;
 	int			i_reloftype;
 	int			i_relpages;
+	int			i_is_identity_sequence;
 	int			i_changed_acl;
 
 	/* Make sure we are in proper schema */
@@ -4924,6 +4928,7 @@ getTables(Archive *fout, int *numTables)
 						  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 						  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "
 						  "tc.reloptions AS toast_reloptions, "
+						  "EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND objsubid = 0 AND refclassid = 'pg_attrdef'::regclass AND deptype = 'i') AS is_identity_sequence, "
 						  "EXISTS (SELECT 1 FROM pg_attribute at LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
 						  "AND pip.classoid = 'pg_class'::regclass "
@@ -5374,6 +5379,7 @@ getTables(Archive *fout, int *numTables)
 	i_checkoption = PQfnumber(res, "checkoption");
 	i_toastreloptions = PQfnumber(res, "toast_reloptions");
 	i_reloftype = PQfnumber(res, "reloftype");
+	i_is_identity_sequence = PQfnumber(res, "is_identity_sequence");
 	i_changed_acl = PQfnumber(res, "changed_acl");
 
 	if (dopt->lockWaitTimeout)
@@ -5474,6 +5480,8 @@ getTables(Archive *fout, int *numTables)
 
 		tblinfo[i].postponed_def = false;		/* might get set during sort */
 
+		tblinfo[i].is_identity_sequence = (strcmp(PQgetvalue(res, i, i_is_identity_sequence), "t") == 0);
+
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
 		 * in schema before we get around to dumping them.
@@ -6925,6 +6933,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	int			i_typstorage;
 	int			i_attnotnull;
 	int			i_atthasdef;
+	int			i_attidentity;
 	int			i_attisdropped;
 	int			i_attlen;
 	int			i_attalign;
@@ -6967,7 +6976,34 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 
 		resetPQExpBuffer(q);
 
-		if (fout->remoteVersion >= 90200)
+		if (fout->remoteVersion >= 100000)
+		{
+			/*
+			 * attidentity is new in version 10.
+			 */
+			appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
+							  "a.attstattarget, a.attstorage, t.typstorage, "
+							  "a.attnotnull, a.atthasdef, a.attisdropped, "
+							  "a.attlen, a.attalign, a.attislocal, "
+				  "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname, "
+						"array_to_string(a.attoptions, ', ') AS attoptions, "
+							  "CASE WHEN a.attcollation <> t.typcollation "
+						   "THEN a.attcollation ELSE 0 END AS attcollation, "
+							  "a.attidentity, "
+							  "pg_catalog.array_to_string(ARRAY("
+							  "SELECT pg_catalog.quote_ident(option_name) || "
+							  "' ' || pg_catalog.quote_literal(option_value) "
+						"FROM pg_catalog.pg_options_to_table(attfdwoptions) "
+							  "ORDER BY option_name"
+							  "), E',\n    ') AS attfdwoptions "
+			 "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
+							  "ON a.atttypid = t.oid "
+							  "WHERE a.attrelid = '%u'::pg_catalog.oid "
+							  "AND a.attnum > 0::pg_catalog.int2 "
+							  "ORDER BY a.attrelid, a.attnum",
+							  tbinfo->dobj.catId.oid);
+		}
+		else if (fout->remoteVersion >= 90200)
 		{
 			/*
 			 * attfdwoptions is new in 9.2.
@@ -7066,6 +7102,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		i_typstorage = PQfnumber(res, "typstorage");
 		i_attnotnull = PQfnumber(res, "attnotnull");
 		i_atthasdef = PQfnumber(res, "atthasdef");
+		i_attidentity = PQfnumber(res, "attidentity");
 		i_attisdropped = PQfnumber(res, "attisdropped");
 		i_attlen = PQfnumber(res, "attlen");
 		i_attalign = PQfnumber(res, "attalign");
@@ -7081,6 +7118,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		tbinfo->attstattarget = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attstorage = (char *) pg_malloc(ntups * sizeof(char));
 		tbinfo->typstorage = (char *) pg_malloc(ntups * sizeof(char));
+		tbinfo->attidentity = (char *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attisdropped = (bool *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attlen = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attalign = (char *) pg_malloc(ntups * sizeof(char));
@@ -7105,6 +7143,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, j, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
+			tbinfo->attidentity[j] = *(PQgetvalue(res, j, i_attidentity));
+			tbinfo->needs_override = tbinfo->needs_override || (tbinfo->attidentity[j] == 'a');
 			tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
 			tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
 			tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
@@ -7150,6 +7190,9 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			{
 				int			adnum;
 
+				if (tbinfo->attidentity[j] != ' ')
+					continue;
+
 				adnum = atoi(PQgetvalue(res, j, 2));
 
 				if (adnum <= 0 || adnum > ntups)
@@ -15170,10 +15213,13 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
-					  fmtId(tbinfo->dobj.namespace->dobj.name));
-	appendPQExpBuffer(delqry, "%s;\n",
-					  fmtId(tbinfo->dobj.name));
+	if (!tbinfo->is_identity_sequence)
+	{
+		appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+		appendPQExpBuffer(delqry, "%s;\n",
+						  fmtId(tbinfo->dobj.name));
+	}
 
 	resetPQExpBuffer(query);
 
@@ -15185,9 +15231,27 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 												tbinfo->dobj.catId.oid);
 	}
 
-	appendPQExpBuffer(query,
-					  "CREATE SEQUENCE %s\n",
-					  fmtId(tbinfo->dobj.name));
+	if (tbinfo->is_identity_sequence)
+	{
+		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+
+		appendPQExpBuffer(query,
+						  "ALTER TABLE %s ",
+						  fmtId(owning_tab->dobj.name));
+		appendPQExpBuffer(query,
+						  "ALTER COLUMN %s ADD GENERATED ",
+						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
+		if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'a')
+			appendPQExpBuffer(query, "ALWAYS");
+		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'd')
+			appendPQExpBuffer(query, "BY DEFAULT");
+		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+						  fmtId(tbinfo->dobj.name));
+	}
+	else
+		appendPQExpBuffer(query,
+						  "CREATE SEQUENCE %s\n",
+						  fmtId(tbinfo->dobj.name));
 
 	if (fout->remoteVersion >= 80400)
 		appendPQExpBuffer(query, "    START WITH %s\n", startv);
@@ -15208,7 +15272,10 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "    CACHE %s%s",
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
-	appendPQExpBufferStr(query, ";\n");
+	if (tbinfo->is_identity_sequence)
+		appendPQExpBufferStr(query, "\n);\n");
+	else
+		appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
@@ -15241,7 +15308,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	 * We need not schema-qualify the table reference because both sequence
 	 * and table must be in the same schema.
 	 */
-	if (OidIsValid(tbinfo->owning_tab))
+	if (OidIsValid(tbinfo->owning_tab) && !tbinfo->is_identity_sequence)
 	{
 		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
 
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index a60cf95..c4eb2c8 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -283,6 +283,7 @@ typedef struct _tableInfo
 	/* these two are set only if table is a sequence owned by a column: */
 	Oid			owning_tab;		/* OID of table owning sequence */
 	int			owning_col;		/* attr # of column owning sequence */
+	bool		is_identity_sequence;
 	int			relpages;		/* table's size in pages (from pg_class) */
 
 	bool		interesting;	/* true if need to collect more data */
@@ -300,6 +301,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	char	   *attidentity;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
 	char	   *attalign;		/* attribute align, used by binary_upgrade */
 	bool	   *attislocal;		/* true if attr has local definition */
@@ -310,6 +312,7 @@ typedef struct _tableInfo
 	bool	   *inhNotNull;		/* true if NOT NULL is inherited */
 	struct _attrDefInfo **attrdefs;		/* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
+	bool		needs_override;	/* has GENERATED ALWAYS AS IDENTITY */
 
 	/*
 	 * Stuff computed only for dumpable tables.
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 6275a68..e751279 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -1547,6 +1547,10 @@ describeOneTableDetails(const char *schemaname,
 							 "   WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation");
 	else
 		appendPQExpBufferStr(&buf, "\n  NULL AS attcollation");
+	if (pset.sversion >= 100000)
+		appendPQExpBufferStr(&buf, ", a.attidentity");
+	else
+		appendPQExpBufferStr(&buf, ", NULL AS attidentity");
 	if (tableinfo.relkind == 'i')
 		appendPQExpBufferStr(&buf, ",\n  pg_catalog.pg_get_indexdef(a.attrelid, a.attnum, TRUE) AS indexdef");
 	else
@@ -1709,9 +1713,11 @@ describeOneTableDetails(const char *schemaname,
 		/* Type */
 		printTableAddCell(&cont, PQgetvalue(res, i, 1), false, false);
 
-		/* Modifiers: collate, not null, default */
+		/* Modifiers: collate, not null, default, identity */
 		if (show_modifiers)
 		{
+			char   *identity;
+
 			resetPQExpBuffer(&tmpbuf);
 
 			if (!PQgetisnull(res, i, 5))
@@ -1729,9 +1735,11 @@ describeOneTableDetails(const char *schemaname,
 				appendPQExpBufferStr(&tmpbuf, _("not null"));
 			}
 
+			identity = PQgetvalue(res, i, 6);
+
 			/* handle "default" here */
 			/* (note: above we cut off the 'default' string at 128) */
-			if (strlen(PQgetvalue(res, i, 2)) != 0)
+			if (strlen(PQgetvalue(res, i, 2)) != 0 && identity[0] == ' ')
 			{
 				if (tmpbuf.len > 0)
 					appendPQExpBufferChar(&tmpbuf, ' ');
@@ -1740,6 +1748,16 @@ describeOneTableDetails(const char *schemaname,
 								  PQgetvalue(res, i, 2));
 			}
 
+			if (strlen(identity) != 0 && (identity[0] == 'a' || identity[0] == 'd'))
+			{
+				if (tmpbuf.len > 0)
+					appendPQExpBufferChar(&tmpbuf, ' ');
+				if (identity[0] == 'a')
+					appendPQExpBuffer(&tmpbuf, "generated always as identity");
+				else if (identity[0] == 'd')
+					appendPQExpBuffer(&tmpbuf, "generated by default as identity");
+			}
+
 			modifiers[i] = pg_strdup(tmpbuf.data);
 			printTableAddCell(&cont, modifiers[i], false, false);
 		}
@@ -1750,16 +1768,16 @@ describeOneTableDetails(const char *schemaname,
 
 		/* Expression for index column */
 		if (tableinfo.relkind == 'i')
-			printTableAddCell(&cont, PQgetvalue(res, i, 6), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
 
 		/* FDW options for foreign table column, only for 9.2 or later */
 		if (tableinfo.relkind == 'f' && pset.sversion >= 90200)
-			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 8), false, false);
 
 		/* Storage and Description */
 		if (verbose)
 		{
-			int			firstvcol = 8;
+			int			firstvcol = 9;
 			char	   *storage = PQgetvalue(res, i, firstvcol);
 
 			/* these strings are literal in our syntax, so not translated. */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 50a45eb..b60b334 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1744,7 +1744,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> */
 	else if (Matches6("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny) ||
 			 Matches5("ALTER", "TABLE", MatchAny, "ALTER", MatchAny))
-		COMPLETE_WITH_LIST4("TYPE", "SET", "RESET", "DROP");
+		COMPLETE_WITH_LIST5("TYPE", "SET", "RESET", "ADD", "DROP");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
@@ -1760,7 +1760,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> DROP */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "DROP") ||
 			 Matches8("ALTER", "TABLE", MatchAny, "TABLE", MatchAny, "ALTER", MatchAny, "DROP"))
-		COMPLETE_WITH_LIST2("DEFAULT", "NOT NULL");
+		COMPLETE_WITH_LIST3("DEFAULT", "IDENTITY", "NOT NULL");
 	else if (Matches4("ALTER", "TABLE", MatchAny, "CLUSTER"))
 		COMPLETE_WITH_CONST("ON");
 	else if (Matches5("ALTER", "TABLE", MatchAny, "CLUSTER", "ON"))
@@ -2621,17 +2621,25 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * Complete INSERT INTO <table> with "(" or "VALUES" or "SELECT" or
-	 * "TABLE" or "DEFAULT VALUES"
+	 * "TABLE" or "DEFAULT VALUES" or "OVERRIDING"
 	 */
 	else if (TailMatches3("INSERT", "INTO", MatchAny))
-		COMPLETE_WITH_LIST5("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES");
+		COMPLETE_WITH_LIST6("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES", "OVERRIDING");
 
 	/*
 	 * Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" or
-	 * "TABLE"
+	 * "TABLE" or "OVERRIDING"
 	 */
 	else if (TailMatches4("INSERT", "INTO", MatchAny, MatchAny) &&
 			 ends_with(prev_wd, ')'))
+		COMPLETE_WITH_LIST4("SELECT", "TABLE", "VALUES", "OVERRIDING");
+
+	/* Complete OVERRIDING */
+	else if (TailMatches1("OVERRIDING"))
+		COMPLETE_WITH_LIST2("SYSTEM VALUE", "USER VALUE");
+
+	/* Complete after OVERRIDING clause */
+	else if (TailMatches3("OVERRIDING", MatchAny, "VALUE"))
 		COMPLETE_WITH_LIST3("SELECT", "TABLE", "VALUES");
 
 	/* Insert an open parenthesis after "VALUES" */
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index cd3048d..089020b 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201610201
+#define CATALOG_VERSION_NO	201610312
 
 #endif
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 09b36c5..96b519b 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -236,7 +236,7 @@ extern bool sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId);
 
 extern void markSequenceUnowned(Oid seqId);
 
-extern List *getOwnedSequences(Oid relid);
+extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
 
 extern Oid	get_constraint_index(Oid constraintId);
 
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 39d8eed..6406b07 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -133,6 +133,9 @@ CATALOG(pg_attribute,1249) BKI_BOOTSTRAP BKI_WITHOUT_OIDS BKI_ROWTYPE_OID(75) BK
 	/* Has DEFAULT value or not */
 	bool		atthasdef;
 
+	/* 'a', 'd', or ' ' */
+	char		attidentity;
+
 	/* Is dropped (ie, logically invisible) or not */
 	bool		attisdropped;
 
@@ -188,7 +191,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
-#define Natts_pg_attribute				21
+#define Natts_pg_attribute				22
 #define Anum_pg_attribute_attrelid		1
 #define Anum_pg_attribute_attname		2
 #define Anum_pg_attribute_atttypid		3
@@ -203,13 +206,14 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 #define Anum_pg_attribute_attalign		12
 #define Anum_pg_attribute_attnotnull	13
 #define Anum_pg_attribute_atthasdef		14
-#define Anum_pg_attribute_attisdropped	15
-#define Anum_pg_attribute_attislocal	16
-#define Anum_pg_attribute_attinhcount	17
-#define Anum_pg_attribute_attcollation	18
-#define Anum_pg_attribute_attacl		19
-#define Anum_pg_attribute_attoptions	20
-#define Anum_pg_attribute_attfdwoptions 21
+#define Anum_pg_attribute_attidentity	15
+#define Anum_pg_attribute_attisdropped	16
+#define Anum_pg_attribute_attislocal	17
+#define Anum_pg_attribute_attinhcount	18
+#define Anum_pg_attribute_attcollation	19
+#define Anum_pg_attribute_attacl		20
+#define Anum_pg_attribute_attoptions	21
+#define Anum_pg_attribute_attfdwoptions 22
 
 
 /* ----------------
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index e57b81c..0c9167d 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -145,7 +145,7 @@ typedef FormData_pg_class *Form_pg_class;
  */
 DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n 3 1 _null_ _null_ ));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 21 0 f f f f f f f t n 3 1 _null_ _null_ ));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n 3 1 _null_ _null_ ));
 DESCR("");
 DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 29 0 t f f f f f f t n 3 1 _null_ _null_ ));
 DESCR("");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 392a626..6a89af2 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -72,6 +72,7 @@ extern Datum setval_oid(PG_FUNCTION_ARGS);
 extern Datum setval3_oid(PG_FUNCTION_ARGS);
 extern Datum lastval(PG_FUNCTION_ARGS);
 
+extern List *sequence_options(Oid relid);
 extern Datum pg_sequence_parameters(PG_FUNCTION_ARGS);
 
 extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 6de2cab..7fd9174 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -25,6 +25,13 @@
 #include "nodes/primnodes.h"
 #include "nodes/value.h"
 
+typedef enum OverridingKind
+{
+	OVERRIDING_NOT_SET = 0,
+	OVERRIDING_USER_VALUE,
+	OVERRIDING_SYSTEM_VALUE
+} OverridingKind;
+
 /* Possible sources of a Query */
 typedef enum QuerySource
 {
@@ -131,6 +138,8 @@ typedef struct Query
 
 	List	   *targetList;		/* target list (of TargetEntry) */
 
+	OverridingKind override;	/* OVERRIDING clause */
+
 	OnConflictExpr *onConflict; /* ON CONFLICT DO [NOTHING | UPDATE] */
 
 	List	   *returningList;	/* return-values list (of TargetEntry) */
@@ -596,6 +605,7 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	char		identity;		/* attidentity setting */
 	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
@@ -617,9 +627,10 @@ typedef enum TableLikeOption
 {
 	CREATE_TABLE_LIKE_DEFAULTS = 1 << 0,
 	CREATE_TABLE_LIKE_CONSTRAINTS = 1 << 1,
-	CREATE_TABLE_LIKE_INDEXES = 1 << 2,
-	CREATE_TABLE_LIKE_STORAGE = 1 << 3,
-	CREATE_TABLE_LIKE_COMMENTS = 1 << 4,
+	CREATE_TABLE_LIKE_IDENTITY = 1 << 2,
+	CREATE_TABLE_LIKE_INDEXES = 1 << 3,
+	CREATE_TABLE_LIKE_STORAGE = 1 << 4,
+	CREATE_TABLE_LIKE_COMMENTS = 1 << 5,
 	CREATE_TABLE_LIKE_ALL = PG_INT32_MAX
 } TableLikeOption;
 
@@ -1226,6 +1237,7 @@ typedef struct InsertStmt
 	OnConflictClause *onConflictClause; /* ON CONFLICT clause */
 	List	   *returningList;	/* list of expressions to return */
 	WithClause *withClause;		/* WITH clause */
+	OverridingKind override;	/* OVERRIDING clause */
 } InsertStmt;
 
 /* ----------------------
@@ -1527,7 +1539,10 @@ typedef enum AlterTableType
 	AT_DisableRowSecurity,		/* DISABLE ROW SECURITY */
 	AT_ForceRowSecurity,		/* FORCE ROW SECURITY */
 	AT_NoForceRowSecurity,		/* NO FORCE ROW SECURITY */
-	AT_GenericOptions			/* OPTIONS (...) */
+	AT_GenericOptions,			/* OPTIONS (...) */
+	AT_AddIdentity,				/* ADD IDENTITY */
+	AT_SetIdentity,				/* SET identity column options */
+	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
@@ -1798,6 +1813,7 @@ typedef enum ConstrType			/* types of constraints */
 								 * expect it */
 	CONSTR_NOTNULL,
 	CONSTR_DEFAULT,
+	CONSTR_IDENTITY,
 	CONSTR_CHECK,
 	CONSTR_PRIMARY,
 	CONSTR_UNIQUE,
@@ -1809,6 +1825,9 @@ typedef enum ConstrType			/* types of constraints */
 	CONSTR_ATTR_IMMEDIATE
 } ConstrType;
 
+#define CONSTR_GENERATED_ALWAYS		'a'
+#define CONSTR_GENERATED_DEFAULT	'd'
+
 /* Foreign key action codes */
 #define FKCONSTR_ACTION_NOACTION	'a'
 #define FKCONSTR_ACTION_RESTRICT	'r'
@@ -1836,6 +1855,7 @@ typedef struct Constraint
 	bool		is_no_inherit;	/* is constraint non-inheritable? */
 	Node	   *raw_expr;		/* expr, as untransformed parse tree */
 	char	   *cooked_expr;	/* expr, as nodeToString representation */
+	char		generated_when;
 
 	/* Fields used for unique constraints (UNIQUE and PRIMARY KEY): */
 	List	   *keys;			/* String nodes naming referenced column(s) */
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 17ffef5..c35a77f 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -171,6 +171,7 @@ PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
 PG_KEYWORD("full", FULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("function", FUNCTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("functions", FUNCTIONS, UNRESERVED_KEYWORD)
+PG_KEYWORD("generated", GENERATED, RESERVED_KEYWORD)
 PG_KEYWORD("global", GLOBAL, UNRESERVED_KEYWORD)
 PG_KEYWORD("grant", GRANT, RESERVED_KEYWORD)
 PG_KEYWORD("granted", GRANTED, UNRESERVED_KEYWORD)
@@ -281,6 +282,7 @@ PG_KEYWORD("outer", OUTER_P, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("over", OVER, UNRESERVED_KEYWORD)
 PG_KEYWORD("overlaps", OVERLAPS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("overlay", OVERLAY, COL_NAME_KEYWORD)
+PG_KEYWORD("overriding", OVERRIDING, UNRESERVED_KEYWORD)
 PG_KEYWORD("owned", OWNED, UNRESERVED_KEYWORD)
 PG_KEYWORD("owner", OWNER, UNRESERVED_KEYWORD)
 PG_KEYWORD("parallel", PARALLEL, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index dcb8980..573533b 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -64,6 +64,7 @@ extern Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 extern char *get_attname(Oid relid, AttrNumber attnum);
 extern char *get_relid_attribute_name(Oid relid, AttrNumber attnum);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
+extern char	get_attidentity(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index 97edde1..163a16c 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -66,6 +66,53 @@ SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y
 (2 rows)
 
 DROP TABLE inhg;
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+              Table "public.test_like_id_1"
+ Column |  Type   |               Modifiers               
+--------+---------+---------------------------------------
+ a      | integer | not null generated always as identity
+ b      | text    | 
+
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+ a | b  
+---+----
+ 1 | b1
+(1 row)
+
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+Table "public.test_like_id_2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | not null
+ b      | text    | 
+
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, b2).
+SELECT * FROM test_like_id_2;  -- identity was not copied
+ a | b 
+---+---
+(0 rows)
+
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+              Table "public.test_like_id_3"
+ Column |  Type   |               Modifiers               
+--------+---------+---------------------------------------
+ a      | integer | not null generated always as identity
+ b      | text    | 
+
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+ a | b  
+---+----
+ 1 | b3
+(1 row)
+
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
new file mode 100644
index 0000000..3640a7a
--- /dev/null
+++ b/src/test/regress/expected/identity.out
@@ -0,0 +1,278 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest3" is already an identity column
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+ table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
+------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
+ itest1     | a           |                | NO          | YES         | BY DEFAULT          | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest1     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest2     | a           |                | NO          | YES         | ALWAYS              | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest2     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest3     | a           |                | NO          | YES         | BY DEFAULT          | 7              | 5                  | 9223372036854775807 | 1                | NO
+ itest3     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+(6 rows)
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+ sequence_name 
+---------------
+(0 rows)
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is already an identity column
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  identity column type must be smallint, integer, or bigint
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+ERROR:  identity column type must be smallint, integer, or bigint
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+ERROR:  multiple identity specifications for column "a" of table "itest_err_2"
+LINE 1: ...E itest_err_2 (a int generated always as identity generated ...
+                                                             ^
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_3"
+LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau...
+                                                  ^
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_4"
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest1;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest2;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest3;
+ a  | b 
+----+---
+  7 | 
+ 12 | 
+(2 rows)
+
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+-- OVERRIDING tests
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+SELECT * FROM itest1;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+(3 rows)
+
+-- UPDATE tests
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+  a  |  b  
+-----+-----
+  10 | xyz
+   3 | xyz
+ 101 | 
+   4 | 
+(4 rows)
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+ERROR:  column "a" can only be updated to DEFAULT
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+ 10 | xyz
+  3 | 
+(3 rows)
+
+-- DROP IDENTITY tests
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is not an identity column
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+   | 
+(3 rows)
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+ERROR:  relation "itest4_a_seq" does not exist
+LINE 1: SELECT sequence_name FROM itest4_a_seq;
+                                  ^
+-- test views
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+SELECT * FROM itestv10;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itestv11;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv10;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv11;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 11 | xyz
+(3 rows)
+
+-- various tests
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+ERROR:  column "a" of relation "itest1" is an identity column
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ERROR:  column "a" of relation "itest5" already has a default value
+-- not allowed for now
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;
+ERROR:  cannot alter data type of identity column "a"
+-- ALTER COLUMN
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+  a  | b 
+-----+---
+   1 | 
+ 100 | 
+ 102 | 
+(3 rows)
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+ table_name | column_name | is_identity | identity_generation 
+------------+-------------+-------------+---------------------
+ itest6     | a           | YES         | BY DEFAULT
+ itest6     | b           | NO          | 
+(2 rows)
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+ERROR:  column "b" of relation "itest6" is not an identity column
+-- inheritance
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+(1 row)
+
+-- inherit identity column
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+INSERT INTO itest7a DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+ 2
+(2 rows)
+
+SELECT * FROM itest7a;
+ a | b 
+---+---
+ 2 | 
+(1 row)
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+NOTICE:  merging column "a" with inherited definition
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+ a 
+---
+ 1
+(1 row)
+
+-- conflicting identity specifications not allowed
+CREATE TABLE itest7d (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7);
+NOTICE:  merging column "a" with inherited definition
+ERROR:  column "a" has conflicting identity definitions
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+ table_name | column_name | is_nullable | is_identity | identity_generation 
+------------+-------------+-------------+-------------+---------------------
+ itest7     | a           | NO          | YES         | ALWAYS
+ itest7a    | a           | NO          | YES         | ALWAYS
+ itest7a    | b           | YES         | NO          | 
+ itest7b    | a           | YES         | NO          | 
+ itest7c    | a           | NO          | YES         | ALWAYS
+(5 rows)
+
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index 5c5277e..c76a217 100644
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -393,6 +393,36 @@ SELECT * FROM truncate_a;
   2 |  34
 (2 rows)
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
+TRUNCATE truncate_b;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 46
+ 47
+(2 rows)
+
+TRUNCATE truncate_b RESTART IDENTITY;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 8641769..9ff4bd4 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -108,6 +108,11 @@ test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combo
 # ----------
 test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml
 
+# ----------
+# Another group of parallel tests
+# ----------
+test: identity
+
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger
 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 835cf35..1f022ae 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -161,6 +161,7 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
+test: identity
 test: polymorphism
 test: rowtypes
 test: returning
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 6dded1f..4b8bfc5 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -37,6 +37,20 @@ CREATE TABLE inhg (x text, LIKE inhx INCLUDING CONSTRAINTS, y text); /* Copies c
 SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y */
 DROP TABLE inhg;
 
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+SELECT * FROM test_like_id_2;  -- identity was not copied
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
+
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
new file mode 100644
index 0000000..6390a5c
--- /dev/null
+++ b/src/test/regress/sql/identity.sql
@@ -0,0 +1,156 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+
+SELECT * FROM itest1;
+SELECT * FROM itest2;
+SELECT * FROM itest3;
+SELECT * FROM itest4;
+
+
+-- OVERRIDING tests
+
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest1;
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest2;
+
+
+-- UPDATE tests
+
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+
+
+-- DROP IDENTITY tests
+
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+
+
+-- test views
+
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+
+SELECT * FROM itestv10;
+SELECT * FROM itestv11;
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv10;
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv11;
+
+
+-- various tests
+
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+
+-- not allowed for now
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;
+
+
+-- ALTER COLUMN
+
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+
+
+-- inheritance
+
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+
+-- inherit identity column
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+INSERT INTO itest7a DEFAULT VALUES;
+SELECT * FROM itest7;
+SELECT * FROM itest7a;
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+
+-- conflicting identity specifications not allowed
+CREATE TABLE itest7d (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7);
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index a3d6f53..1aab021 100644
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -202,6 +202,24 @@ CREATE TABLE truncate_a (id serial,
 INSERT INTO truncate_a DEFAULT VALUES;
 SELECT * FROM truncate_a;
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b RESTART IDENTITY;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;

From eee7443a04676a2b22892fb8114d2814e720b8ed Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Sat, 31 Dec 2016 12:00:00 -0500
Subject: [PATCH v3] Identity columns

This is the SQL standard-conforming variant of PostgreSQL's serial
columns.  It also fixes a few usability issues that serial columns
have:

- CREATE TABLE / LIKE copies default but refers to same sequence
- cannot add/drop serialness with ALTER TABLE
- dropping default does not drop sequence
- slight weirdnesses because serial is some kind of special macro
---
 doc/src/sgml/catalogs.sgml                      |  11 +
 doc/src/sgml/information_schema.sgml            |  11 +-
 doc/src/sgml/ref/alter_table.sgml               |  29 ++
 doc/src/sgml/ref/create_table.sgml              |  58 +++-
 doc/src/sgml/ref/insert.sgml                    |  41 +++
 src/backend/access/common/tupdesc.c             |   5 +
 src/backend/catalog/genbki.pl                   |   2 +
 src/backend/catalog/heap.c                      |  15 +-
 src/backend/catalog/index.c                     |   1 +
 src/backend/catalog/information_schema.sql      |  19 +-
 src/backend/catalog/pg_depend.c                 |  17 +-
 src/backend/catalog/sql_features.txt            |  12 +-
 src/backend/commands/sequence.c                 | 108 ++++++-
 src/backend/commands/tablecmds.c                | 287 ++++++++++++++++-
 src/backend/nodes/copyfuncs.c                   |   4 +
 src/backend/nodes/equalfuncs.c                  |   4 +
 src/backend/nodes/makefuncs.c                   |   1 +
 src/backend/nodes/outfuncs.c                    |   9 +
 src/backend/nodes/readfuncs.c                   |   1 +
 src/backend/parser/analyze.c                    |   2 +
 src/backend/parser/gram.y                       | 126 +++++++-
 src/backend/parser/parse_utilcmd.c              | 396 ++++++++++++++++++------
 src/backend/rewrite/rewriteHandler.c            |  43 ++-
 src/backend/utils/adt/ruleutils.c               |   8 +
 src/backend/utils/cache/lsyscache.c             |  21 ++
 src/backend/utils/cache/relcache.c              |   1 +
 src/backend/utils/errcodes.txt                  |   1 +
 src/bin/pg_dump/pg_dump.c                       |  87 +++++-
 src/bin/pg_dump/pg_dump.h                       |   3 +
 src/bin/psql/describe.c                         |  26 +-
 src/bin/psql/tab-complete.c                     |  18 +-
 src/include/catalog/catversion.h                |   2 +-
 src/include/catalog/dependency.h                |   2 +-
 src/include/catalog/pg_attribute.h              |  20 +-
 src/include/catalog/pg_class.h                  |   2 +-
 src/include/commands/sequence.h                 |   1 +
 src/include/nodes/parsenodes.h                  |  28 +-
 src/include/parser/kwlist.h                     |   2 +
 src/include/utils/lsyscache.h                   |   1 +
 src/test/regress/expected/create_table_like.out |  47 +++
 src/test/regress/expected/identity.out          | 274 ++++++++++++++++
 src/test/regress/expected/truncate.out          |  30 ++
 src/test/regress/parallel_schedule              |   5 +
 src/test/regress/serial_schedule                |   1 +
 src/test/regress/sql/create_table_like.sql      |  14 +
 src/test/regress/sql/identity.sql               | 162 ++++++++++
 src/test/regress/sql/truncate.sql               |  18 ++
 47 files changed, 1800 insertions(+), 176 deletions(-)
 create mode 100644 src/test/regress/expected/identity.out
 create mode 100644 src/test/regress/sql/identity.sql

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 493050618d..3c18fffc1c 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1105,6 +1105,17 @@ <title><structname>pg_attribute</> Columns</title>
      </row>
 
      <row>
+      <entry><structfield>attidentity</structfield></entry>
+      <entry><type>char</type></entry>
+      <entry></entry>
+      <entry>
+       If a space character, then not an identity column.  Otherwise,
+       <literal>a</literal> = generated always, <literal>d</literal> =
+       generated by default.
+      </entry>
+     </row>
+
+     <row>
       <entry><structfield>attisdropped</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index c43e325d06..8ece4398ba 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -1583,13 +1583,20 @@ <title><literal>columns</literal> Columns</title>
      <row>
       <entry><literal>is_identity</literal></entry>
       <entry><type>yes_or_no</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>YES</literal>,
+       else <literal>NO</literal>.
+      </entry>
      </row>
 
      <row>
       <entry><literal>identity_generation</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>ALWAYS</literal>
+       or <literal>BY DEFAULT</literal>, reflecting the definition of the
+       column.
+      </entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index da431f8369..be1c7f33a9 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -46,6 +46,9 @@
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESET } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
@@ -180,6 +183,32 @@ <title>Description</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
+    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
+    <term><literal>DROP IDENTITY</literal></term>
+    <listitem>
+     <para>
+      These forms change whether a column is an identity column or change the
+      generation attribute of an existing identity column.
+      See <xref linkend="sql-createtable"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET <replaceable>sequence_option</replaceable></literal></term>
+    <term><literal>RESET</literal></term>
+    <listitem>
+     <para>
+      These forms alter the sequence that underlies an existing identity
+      column.  <replaceable>sequence_option</replaceable> is an option
+      supported by <xref linkend="sql-altersequence"> such
+      as <literal>INCREMENT BY</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>SET STATISTICS</literal></term>
     <listitem>
      <para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 58f8bf6d6a..1d4b6db189 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -62,6 +62,7 @@
   NULL |
   CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
   REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
@@ -81,7 +82,7 @@
 
 <phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
 
-{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
+{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | IDENTITY | INDEXES | STORAGE | COMMENTS | ALL }
 
 <phrase>and <replaceable class="PARAMETER">partition_bound_spec</replaceable> is:</phrase>
 
@@ -442,6 +443,12 @@ <title>Parameters</title>
       the original and new tables.
      </para>
      <para>
+      Any identity specifications of copied column definitions will only be
+      copied if <literal>INCLUDING IDENTITY</literal> is specified.  A new
+      sequence is created for each identity column of the new table, separate
+      from the sequences associated with the old table.
+     </para>
+     <para>
       Not-null constraints are always copied to the new table.
       <literal>CHECK</literal> constraints will be copied only if
       <literal>INCLUDING CONSTRAINTS</literal> is specified.
@@ -473,7 +480,7 @@ <title>Parameters</title>
      </para>
      <para>
       <literal>INCLUDING ALL</literal> is an abbreviated form of
-      <literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
+      <literal>INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
      </para>
      <para>
       Note that unlike <literal>INHERITS</literal>, columns and
@@ -588,6 +595,35 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]</literal></term>
+    <listitem>
+     <para>
+      This clause creates the column as an <firstterm>identity
+      column</firstterm>.  It will have an implicit sequence attached to it
+      and the column in new rows will automatically have values from the
+      sequence assigned to it.
+     </para>
+
+     <para>
+      The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
+      determine how the sequence value is given precedence over a
+      user-specified value in an <command>INSERT</command> statement.
+      If <literal>ALWAYS</literal> is specified, a user-specified value is
+      only accepted if the <command>INSERT</command> statement
+      specifies <literal>OVERRIDING SYSTEM VALUE</literal>.  If <literal>BY
+      DEFAULT</literal> is specified, then the user-specified value takes
+      precedence.  See <xref linkend="sql-insert"> for details.
+     </para>
+
+     <para>
+      The optional <replaceable>sequence_options</replaceable> clause can be
+      used to override the options of the sequence.
+      See <xref linkend="sql-createsequence"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>UNIQUE</> (column constraint)</term>
     <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
 
@@ -1220,7 +1256,7 @@ <title>Notes</title>
 
     <para>
      Using OIDs in new applications is not recommended: where
-     possible, using a <literal>SERIAL</literal> or other sequence
+     possible, using an identity column or other sequence
      generator as the table's primary key is preferred. However, if
      your application does make use of OIDs to identify specific
      rows of a table, it is recommended to create a unique constraint
@@ -1280,7 +1316,7 @@ <title>Examples</title>
 );
 
 CREATE TABLE distributors (
-     did    integer PRIMARY KEY DEFAULT nextval('serial'),
+     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
      name   varchar(40) NOT NULL CHECK (name &lt;&gt; '')
 );
 </programlisting>
@@ -1664,6 +1700,20 @@ <title>Zero-column Tables</title>
   </refsect2>
 
   <refsect2>
+   <title>Multiple Identity Columns</title>
+
+   <para>
+    <productname>PostgreSQL</productname> allows a table to have more than one
+    identity column.  The standard specifies that a table can have at most one
+    identity column.  This is relaxed mainly to give more flexibility for
+    doing schema changes or migrations.  Note that
+    the <command>INSERT</command> command supports only one override clause
+    that applies to the entire statement, so having multiple identity columns
+    with different behaviors is not well supported.
+   </para>
+  </refsect2>
+
+  <refsect2>
    <title><literal>LIKE</> Clause</title>
 
    <para>
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 9339826818..4cef7e92b8 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -23,6 +23,7 @@
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
 INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replaceable class="parameter">alias</replaceable> ] [ ( <replaceable class="PARAMETER">column_name</replaceable> [, ...] ) ]
+    [ OVERRIDING { SYSTEM | USER} VALUE ]
     { DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
     [ ON CONFLICT [ <replaceable class="parameter">conflict_target</replaceable> ] <replaceable class="parameter">conflict_action</replaceable> ]
     [ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@@ -202,10 +203,43 @@ <title id="sql-inserting-params-title">Inserting</title>
      </varlistentry>
 
      <varlistentry>
+      <term><literal>OVERRIDING SYSTEM VALUE</literal></term>
+      <listitem>
+       <para>
+        Without this clause, it is an error to specify an explicit value
+        (other than <literal>DEFAULT</literal>) for an identity column defined
+        as <literal>GENERATED ALWAYS</literal>.  This clause overrides that
+        restriction.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>OVERRIDING USER VALUE</literal></term>
+      <listitem>
+       <para>
+        If this clause is specified, then any values supplied for identity
+        columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
+        and the default sequence-generated values are applied.
+       </para>
+
+       <para>
+        This clause is useful for example when copying values between tables.
+        Writing <literal>INSERT INTO tbl2 OVERRIDING USER VALUE SELECT * FROM
+        tbl1</literal> will copy from <literal>tbl1</literal> all columns that
+        are not identity columns in <literal>tbl2</literal> but will continue
+        the sequence counters for any identity columns.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>DEFAULT VALUES</literal></term>
       <listitem>
        <para>
         All columns will be filled with their default values.
+        (An <literal>OVERRIDING</literal> clause is not permitted in this
+        form.)
        </para>
       </listitem>
      </varlistentry>
@@ -711,6 +745,13 @@ <title>Compatibility</title>
   </para>
 
   <para>
+   The SQL standard specifies that <literal>OVERRIDING SYSTEM VALUE</literal>
+   can only be specified if an identity column that is generated always
+   exists.  PostgreSQL allows the clause in any case and ignores it if it is
+   not applicable.
+  </para>
+
+  <para>
    Possible limitations of the <replaceable
    class="PARAMETER">query</replaceable> clause are documented under
    <xref linkend="sql-select">.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index b56d0e336f..8a8244ec42 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -149,6 +149,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 		desc->attrs[i]->attnotnull = false;
 		desc->attrs[i]->atthasdef = false;
+		desc->attrs[i]->attidentity = ' ';
 	}
 
 	desc->tdtypeid = tupdesc->tdtypeid;
@@ -256,6 +257,7 @@ TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 	/* since we're not copying constraints or defaults, clear these */
 	dst->attrs[dstAttno - 1]->attnotnull = false;
 	dst->attrs[dstAttno - 1]->atthasdef = false;
+	dst->attrs[dstAttno - 1]->attidentity = ' ';
 }
 
 /*
@@ -400,6 +402,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atthasdef != attr2->atthasdef)
 			return false;
+		if (attr1->attidentity != attr2->attidentity)
+			return false;
 		if (attr1->attisdropped != attr2->attisdropped)
 			return false;
 		if (attr1->attislocal != attr2->attislocal)
@@ -533,6 +537,7 @@ TupleDescInitEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = ' ';
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 26d165203d..f0d79c324a 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -409,6 +409,7 @@ sub emit_pgattr_row
 		attcacheoff   => '-1',
 		atttypmod     => '-1',
 		atthasdef     => 'f',
+		attidentity   => "' '",
 		attisdropped  => 'f',
 		attislocal    => 't',
 		attinhcount   => '0',
@@ -425,6 +426,7 @@ sub bki_insert
 	my @attnames   = @_;
 	my $oid        = $row->{oid} ? "OID = $row->{oid} " : '';
 	my $bki_values = join ' ', map $row->{$_}, @attnames;
+	$bki_values =~ s/'/"/g;
 	printf BKI "insert %s( %s)\n", $oid, $bki_values;
 }
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index e5d6aecc3f..c0f66425c1 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -142,37 +142,37 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
 static FormData_pg_attribute a1 = {
 	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
 	SelfItemPointerAttributeNumber, 0, -1, -1,
-	false, 'p', 's', true, false, false, true, 0
+	false, 'p', 's', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a2 = {
 	0, {"oid"}, OIDOID, 0, sizeof(Oid),
 	ObjectIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a3 = {
 	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
 	MinTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a4 = {
 	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
 	MinCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a5 = {
 	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
 	MaxTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a6 = {
 	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
 	MaxCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 /*
@@ -184,7 +184,7 @@ static FormData_pg_attribute a6 = {
 static FormData_pg_attribute a7 = {
 	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
 	TableOidAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
@@ -628,6 +628,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
 	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
 	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
+	values[Anum_pg_attribute_attidentity - 1] = CharGetDatum(new_attribute->attidentity);
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 08b0989112..eca570eb49 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -353,6 +353,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->attnotnull = false;
 			to->atthasdef = false;
+			to->attidentity = ' ';
 			to->attislocal = true;
 			to->attinhcount = 0;
 			to->attcollation = collationObjectId[i];
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index 182d2d0674..8d86cafc6c 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -646,7 +646,7 @@ CREATE VIEW columns AS
            CAST(c.relname AS sql_identifier) AS table_name,
            CAST(a.attname AS sql_identifier) AS column_name,
            CAST(a.attnum AS cardinal_number) AS ordinal_position,
-           CAST(pg_get_expr(ad.adbin, ad.adrelid) AS character_data) AS column_default,
+           CAST(CASE WHEN a.atthasdef AND a.attidentity = ' ' THEN pg_get_expr(ad.adbin, ad.adrelid) END AS character_data) AS column_default,
            CAST(CASE WHEN a.attnotnull OR (t.typtype = 'd' AND t.typnotnull) THEN 'NO' ELSE 'YES' END
              AS yes_or_no)
              AS is_nullable,
@@ -727,13 +727,13 @@ CREATE VIEW columns AS
            CAST(a.attnum AS sql_identifier) AS dtd_identifier,
            CAST('NO' AS yes_or_no) AS is_self_referencing,
 
-           CAST('NO' AS yes_or_no) AS is_identity,
-           CAST(null AS character_data) AS identity_generation,
-           CAST(null AS character_data) AS identity_start,
-           CAST(null AS character_data) AS identity_increment,
-           CAST(null AS character_data) AS identity_maximum,
-           CAST(null AS character_data) AS identity_minimum,
-           CAST(null AS yes_or_no) AS identity_cycle,
+           CAST(CASE WHEN a.attidentity IN ('a', 'd') THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_identity,
+           CAST(CASE a.attidentity WHEN 'a' THEN 'ALWAYS' WHEN 'd' THEN 'BY DEFAULT' END AS character_data) AS identity_generation,
+           CAST(p.start_value AS character_data) AS identity_start,
+           CAST(p.increment AS character_data) AS identity_increment,
+           CAST(p.maximum_value AS character_data) AS identity_maximum,
+           CAST(p.minimum_value AS character_data) AS identity_minimum,
+           CAST(CASE WHEN p.cycle_option THEN 'YES' ELSE 'NO' END AS yes_or_no) AS identity_cycle,
 
            CAST('NEVER' AS character_data) AS is_generated,
            CAST(null AS character_data) AS generation_expression,
@@ -750,6 +750,8 @@ CREATE VIEW columns AS
            ON (t.typtype = 'd' AND t.typbasetype = bt.oid)
          LEFT JOIN (pg_collation co JOIN pg_namespace nco ON (co.collnamespace = nco.oid))
            ON a.attcollation = co.oid AND (nco.nspname, co.collname) <> ('pg_catalog', 'default')
+         LEFT JOIN (pg_depend dep JOIN pg_class seq ON (dep.classid = 'pg_class'::regclass AND dep.objid = seq.oid AND dep.deptype = 'i') JOIN LATERAL pg_sequence_parameters(seq.oid) p ON true)
+           ON (dep.refclassid = 'pg_attrdef'::regclass AND dep.refobjid = ad.oid)
 
     WHERE (NOT pg_is_other_temp_schema(nc.oid))
 
@@ -1543,6 +1545,7 @@ CREATE VIEW sequences AS
     FROM pg_namespace nc, pg_class c, pg_sequence s
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
+          AND NOT EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND deptype = 'i')
           AND (NOT pg_is_other_temp_schema(nc.oid))
           AND c.oid = s.seqrelid
           AND (pg_has_role(c.relowner, 'USAGE')
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index 7a0713e6cc..0823b882f9 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -19,6 +19,7 @@
 #include "access/htup_details.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
+#include "catalog/pg_attrdef.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_depend.h"
 #include "catalog/pg_extension.h"
@@ -554,17 +555,20 @@ markSequenceUnowned(Oid seqId)
 {
 	deleteDependencyRecordsForClass(RelationRelationId, seqId,
 									RelationRelationId, DEPENDENCY_AUTO);
+	deleteDependencyRecordsForClass(RelationRelationId, seqId,
+									AttrDefaultRelationId, DEPENDENCY_INTERNAL);
 }
 
 /*
- * Collect a list of OIDs of all sequences owned by the specified relation.
+ * Collect a list of OIDs of all sequences owned by the specified relation,
+ * and column if specified.
  */
 List *
-getOwnedSequences(Oid relid)
+getOwnedSequences(Oid relid, AttrNumber attnum)
 {
 	List	   *result = NIL;
 	Relation	depRel;
-	ScanKeyData key[2];
+	ScanKeyData key[3];
 	SysScanDesc scan;
 	HeapTuple	tup;
 
@@ -578,9 +582,14 @@ getOwnedSequences(Oid relid)
 				Anum_pg_depend_refobjid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(relid));
+	if (attnum)
+		ScanKeyInit(&key[2],
+					Anum_pg_depend_refobjsubid,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(attnum));
 
 	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 2, key);
+							  NULL, attnum ? 3 : 2, key);
 
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 8956ba9304..2821b9b702 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -200,7 +200,7 @@ F181	Multiple module support			NO
 F191	Referential delete actions			YES	
 F200	TRUNCATE TABLE statement			YES	
 F201	CAST function			YES	
-F202	TRUNCATE TABLE: identity column restart option			NO	
+F202	TRUNCATE TABLE: identity column restart option			YES	
 F221	Explicit defaults			YES	
 F222	INSERT statement: DEFAULT VALUES clause			YES	
 F231	Privilege tables			YES	
@@ -241,9 +241,9 @@ F381	Extended schema manipulation	02	ALTER TABLE statement: ADD CONSTRAINT claus
 F381	Extended schema manipulation	03	ALTER TABLE statement: DROP CONSTRAINT clause	YES	
 F382	Alter column data type			YES	
 F383	Set column not null clause			YES	
-F384	Drop identity property clause			NO	
+F384	Drop identity property clause			YES	
 F385	Drop column generation expression clause			NO	
-F386	Set identity column generation clause			NO	
+F386	Set identity column generation clause			YES	
 F391	Long identifiers			YES	
 F392	Unicode escapes in identifiers			YES	
 F393	Unicode escapes in literals			YES	
@@ -420,11 +420,11 @@ T152	DISTINCT predicate with negation			YES
 T171	LIKE clause in table definition			YES	
 T172	AS subquery clause in table definition			YES	
 T173	Extended LIKE clause in table definition			YES	
-T174	Identity columns			NO	
+T174	Identity columns			YES	
 T175	Generated columns			NO	
 T176	Sequence generator support			NO	
-T177	Sequence generator support: simple restart option			NO	
-T178	Identity columns:  simple restart option			NO	
+T177	Sequence generator support: simple restart option			YES	
+T178	Identity columns:  simple restart option			YES	
 T180	System-versioned tables			NO	
 T181	Application-time period tables			NO	
 T191	Referential action RESTRICT			YES	
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 668d82771a..f5e6a4f6e4 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -25,6 +25,7 @@
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/objectaccess.h"
+#include "catalog/pg_attrdef.h"
 #include "catalog/pg_sequence.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
@@ -38,6 +39,7 @@
 #include "storage/smgr.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
+#include "utils/fmgroids.h"
 #include "utils/lsyscache.h"
 #include "utils/resowner.h"
 #include "utils/syscache.h"
@@ -98,9 +100,10 @@ static Form_pg_sequence_data read_seq_tuple(Relation rel,
 			   Buffer *buf, HeapTuple seqdatatuple);
 static void init_params(ParseState *pstate, List *options, bool isInit,
 						Form_pg_sequence seqform,
-						Form_pg_sequence_data seqdataform, List **owned_by);
+						Form_pg_sequence_data seqdataform, List **owned_by,
+						DependencyType *deptype);
 static void do_setval(Oid relid, int64 next, bool iscalled);
-static void process_owned_by(Relation seqrel, List *owned_by);
+static void process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype);
 
 
 /*
@@ -113,6 +116,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	FormData_pg_sequence seqform;
 	FormData_pg_sequence_data seqdataform;
 	List	   *owned_by;
+	DependencyType deptype;
 	CreateStmt *stmt = makeNode(CreateStmt);
 	Oid			seqoid;
 	ObjectAddress address;
@@ -150,7 +154,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	}
 
 	/* Check and set all option values */
-	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by);
+	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by, &deptype);
 
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
@@ -167,6 +171,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 		coldef->storage = 0;
 		coldef->raw_default = NULL;
 		coldef->cooked_default = NULL;
+		coldef->identity = ' ';
 		coldef->collClause = NULL;
 		coldef->collOid = InvalidOid;
 		coldef->constraints = NIL;
@@ -216,7 +221,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(rel, owned_by);
+		process_owned_by(rel, owned_by, deptype);
 
 	heap_close(rel, NoLock);
 
@@ -415,6 +420,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	Form_pg_sequence_data seqdata;
 	FormData_pg_sequence_data newseqdata;
 	List	   *owned_by;
+	DependencyType deptype;
 	ObjectAddress address;
 	Relation	rel;
 	HeapTuple	tuple;
@@ -452,7 +458,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	seqform = (Form_pg_sequence) GETSTRUCT(tuple);
 
 	/* Check and set new values */
-	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by);
+	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by, &deptype);
 
 	/* Clear local cache so that we don't think we have cached numbers */
 	/* Note that we do not change the currval() state */
@@ -495,7 +501,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(seqrel, owned_by);
+		process_owned_by(seqrel, owned_by, deptype);
 
 	InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
@@ -1219,7 +1225,8 @@ read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
 static void
 init_params(ParseState *pstate, List *options, bool isInit,
 			Form_pg_sequence seqform,
-			Form_pg_sequence_data seqdataform, List **owned_by)
+			Form_pg_sequence_data seqdataform, List **owned_by,
+			DependencyType *deptype)
 {
 	DefElem    *start_value = NULL;
 	DefElem    *restart_value = NULL;
@@ -1228,9 +1235,11 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	DefElem    *min_value = NULL;
 	DefElem    *cache_value = NULL;
 	DefElem    *is_cycled = NULL;
+	DefElem	   *deptype_el = NULL;
 	ListCell   *option;
 
 	*owned_by = NIL;
+	*deptype = DEPENDENCY_AUTO;
 
 	foreach(option, options)
 	{
@@ -1308,6 +1317,15 @@ init_params(ParseState *pstate, List *options, bool isInit,
 						 parser_errposition(pstate, defel->location)));
 			*owned_by = defGetQualifiedName(defel);
 		}
+		else if (strcmp(defel->defname, "deptype") == 0)
+		{
+			if (deptype_el)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			deptype_el = defel;
+			*deptype = intVal(deptype_el->arg);
+		}
 		else
 			elog(ERROR, "option \"%s\" not recognized",
 				 defel->defname);
@@ -1486,6 +1504,38 @@ init_params(ParseState *pstate, List *options, bool isInit,
 		seqform->seqcache = 1;
 }
 
+static Oid
+get_attrdef_oid(Oid relid, AttrNumber attnum)
+{
+	Relation    attrdef_rel;
+	ScanKeyData scankeys[2];
+	SysScanDesc scan;
+	HeapTuple   tuple;
+	Oid			result = InvalidOid;
+
+	attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);
+
+	ScanKeyInit(&scankeys[0],
+				Anum_pg_attrdef_adrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(relid));
+	ScanKeyInit(&scankeys[1],
+				Anum_pg_attrdef_adnum,
+				BTEqualStrategyNumber, F_INT2EQ,
+				Int16GetDatum(attnum));
+
+	scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
+							  NULL, 2, scankeys);
+
+	if (HeapTupleIsValid(tuple = systable_getnext(scan)))
+		result = HeapTupleGetOid(tuple);
+
+	systable_endscan(scan);
+	heap_close(attrdef_rel, RowExclusiveLock);
+
+	return result;
+}
+
 /*
  * Process an OWNED BY option for CREATE/ALTER SEQUENCE
  *
@@ -1495,7 +1545,7 @@ init_params(ParseState *pstate, List *options, bool isInit,
  * as the sequence.
  */
 static void
-process_owned_by(Relation seqrel, List *owned_by)
+process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype)
 {
 	int			nnames;
 	Relation	tablerel;
@@ -1531,6 +1581,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		/* Must be a regular or foreign table */
 		if (!(tablerel->rd_rel->relkind == RELKIND_RELATION ||
 			  tablerel->rd_rel->relkind == RELKIND_FOREIGN_TABLE ||
+			  tablerel->rd_rel->relkind == RELKIND_VIEW ||
 			  tablerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
@@ -1574,6 +1625,20 @@ process_owned_by(Relation seqrel, List *owned_by)
 		depobject.objectId = RelationGetRelid(seqrel);
 		depobject.objectSubId = 0;
 		recordDependencyOn(&depobject, &refobject, DEPENDENCY_AUTO);
+
+		/*
+		 * For identity columns, also record an internal dependency of the
+		 * sequence on the default (you drop the default, the sequence is
+		 * removed).  We still do the auto dependency on the column, because
+		 * that is what TRUNCATE RESTART IDENTITY looks for.
+		 */
+		if (deptype == DEPENDENCY_INTERNAL)
+		{
+			refobject.classId = AttrDefaultRelationId;
+			refobject.objectId = get_attrdef_oid(RelationGetRelid(tablerel), attnum);
+			refobject.objectSubId = 0;
+			recordDependencyOn(&depobject, &refobject, DEPENDENCY_INTERNAL);
+		}
 	}
 
 	/* Done, but hold lock until commit */
@@ -1583,6 +1648,33 @@ process_owned_by(Relation seqrel, List *owned_by)
 
 
 /*
+ * Return sequence parameters in a list of the form created by the parser.
+ */
+List *
+sequence_options(Oid relid)
+{
+	HeapTuple	pgstuple;
+	Form_pg_sequence pgsform;
+	List	   *options = NIL;
+
+	pgstuple = SearchSysCache1(SEQRELID, relid);
+	if (!HeapTupleIsValid(pgstuple))
+		elog(ERROR, "cache lookup failed for sequence %u", relid);
+	pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
+
+	options = lappend(options, makeDefElem("cache", (Node *) makeInteger(pgsform->seqcache), -1));
+	options = lappend(options, makeDefElem("cycle", (Node *) makeInteger(pgsform->seqcycle), -1));
+	options = lappend(options, makeDefElem("increment", (Node *) makeInteger(pgsform->seqincrement), -1));
+	options = lappend(options, makeDefElem("maxvalue", (Node *) makeInteger(pgsform->seqmax), -1));
+	options = lappend(options, makeDefElem("minvalue", (Node *) makeInteger(pgsform->seqmin), -1));
+	options = lappend(options, makeDefElem("start", (Node *) makeInteger(pgsform->seqstart), -1));
+
+	ReleaseSysCache(pgstuple);
+
+	return options;
+}
+
+/*
  * Return sequence parameters (formerly for use by information schema)
  */
 Datum
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2f605ce83d..bec6e6ffa2 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -358,6 +358,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@@ -698,6 +703,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1283,7 +1291,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;
 
 			foreach(seqcell, seqlist)
@@ -1804,6 +1812,15 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				continue;		/* leave newattno entry as zero */
 
 			/*
+			 * XXX This could be done, but it needs more thought on what it
+			 * means.
+			 */
+			if (attribute->attidentity != ' ')
+				ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("cannot inherit from table with identity column")));
+
+			/*
 			 * Does it conflict with some previously inherited column?
 			 */
 			exist_attno = findAttrByName(attributeName, inhSchema);
@@ -1877,6 +1894,7 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 				def->storage = attribute->attstorage;
 				def->raw_default = NULL;
 				def->cooked_default = NULL;
+				def->identity = attribute->attidentity;
 				def->collClause = NULL;
 				def->collOid = attribute->attcollation;
 				def->constraints = NIL;
@@ -2072,6 +2090,14 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   get_collation_name(newcollid))));
 
+				/*
+				 * def->identity is always ' ' because of the prohibition
+				 * against inheriting from identity columns enforced earlier.
+				 * The new column can have an identity definition, so we
+				 * always just take that one.
+				 */
+				def->identity = newdef->identity;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@@ -3212,6 +3238,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -3430,6 +3459,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_ADD_COL;
 			break;
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
+		case AT_AddIdentity:
+		case AT_DropIdentity:
 
 			/*
 			 * We allow defaults on views so that INSERT into a view can have
@@ -3442,6 +3473,11 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATPrepDropNotNull(rel, recurse, recursing);
@@ -3767,6 +3803,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@@ -5119,6 +5164,11 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		elog(ERROR, "cache lookup failed for relation %u", myrelid);
 	relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
 
+	if (colDef->identity != ' ' && find_inheritance_children(myrelid, NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot add identity column to table that has child tables")));
+
 	/* skip if the name already exists and if_not_exists is true */
 	if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
 	{
@@ -5171,6 +5221,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = ' ';
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@@ -5480,6 +5531,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		cdef->is_local = true;
 		cdef->is_not_null = true;
 		cdef->storage = 0;
+		cdef->identity = ' ';
 		cdef->location = -1;
 		cmd->def = (Node *) cdef;
 	}
@@ -5759,6 +5811,12 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@@ -5794,6 +5852,225 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	RawColumnDefault *rawEnt;
+	ObjectAddress address;
+	ColumnDef  *cdef = (ColumnDef *) def;
+
+	Assert(IsA(def, ColumnDef));
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	/*
+	 * MergeAttributes() disallows inheriting from table with identity column,
+	 * so we have to prevent adding one later on.
+	 */
+	if (find_inheritance_children(RelationGetRelid(rel), NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot add identity to table that has child tables")));
+
+	/*
+	 * Creating a column as identity implies NOT NULL, so adding the identity
+	 * to an existing column that is not NOT NULL would create a state that
+	 * cannot be reproduced without contortions.
+	 */
+	if (!attTup->attnotnull)
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->attidentity != ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	simple_heap_update(attrelation, &tuple->t_self, tuple);
+	CatalogUpdateIndexes(attrelation, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	CommandCounterIncrement();
+
+	rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
+	rawEnt->attnum = attnum;
+	rawEnt->raw_default = cdef->raw_default;
+
+	AddRelationNewConstraints(rel, list_make1(rawEnt), NIL,
+							  false, true, false);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, (List *) def)
+	{
+		DefElem	   *defel = (DefElem *) lfirst(option);
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		simple_heap_update(attrelation, &tuple->t_self, tuple);
+		CatalogUpdateIndexes(attrelation, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = ' ';
+	simple_heap_update(attrelation, &tuple->t_self, tuple);
+	CatalogUpdateIndexes(attrelation, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	CommandCounterIncrement();
+
+	RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false,
+					  true);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET STATISTICS
  */
 static void
@@ -8426,6 +8703,14 @@ ATPrepAlterColumnType(List **wqueue,
 				 errmsg("cannot alter inherited column \"%s\"",
 						colName)));
 
+	/* Don't alter identity columns.  (XXX This could be done, but needs more
+	 * work to check permitted types, adjust sequence.) */
+	if (attTup->attidentity != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot alter data type of identity column \"%s\"",
+						colName)));
+
 	/* Don't alter columns used in the partition key */
 	if (is_partition_attr(rel, attnum, &is_expr))
 	{
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 6955298577..a9eb4029e1 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2623,6 +2623,7 @@ _copyColumnDef(const ColumnDef *from)
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_SCALAR_FIELD(identity);
 	COPY_NODE_FIELD(collClause);
 	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
@@ -2645,6 +2646,7 @@ _copyConstraint(const Constraint *from)
 	COPY_SCALAR_FIELD(is_no_inherit);
 	COPY_NODE_FIELD(raw_expr);
 	COPY_STRING_FIELD(cooked_expr);
+	COPY_SCALAR_FIELD(generated_when);
 	COPY_NODE_FIELD(keys);
 	COPY_NODE_FIELD(exclusions);
 	COPY_NODE_FIELD(options);
@@ -2753,6 +2755,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
 	COPY_NODE_FIELD(targetList);
+	COPY_SCALAR_FIELD(override);
 	COPY_NODE_FIELD(onConflict);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(groupClause);
@@ -2782,6 +2785,7 @@ _copyInsertStmt(const InsertStmt *from)
 	COPY_NODE_FIELD(onConflictClause);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(withClause);
+	COPY_SCALAR_FIELD(override);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 548a2aa876..6b3ae4d81d 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -932,6 +932,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
 	COMPARE_NODE_FIELD(targetList);
+	COMPARE_SCALAR_FIELD(override);
 	COMPARE_NODE_FIELD(onConflict);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(groupClause);
@@ -959,6 +960,7 @@ _equalInsertStmt(const InsertStmt *a, const InsertStmt *b)
 	COMPARE_NODE_FIELD(onConflictClause);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(withClause);
+	COMPARE_SCALAR_FIELD(override);
 
 	return true;
 }
@@ -2382,6 +2384,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_SCALAR_FIELD(identity);
 	COMPARE_NODE_FIELD(collClause);
 	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
@@ -2402,6 +2405,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_SCALAR_FIELD(is_no_inherit);
 	COMPARE_NODE_FIELD(raw_expr);
 	COMPARE_STRING_FIELD(cooked_expr);
+	COMPARE_SCALAR_FIELD(generated_when);
 	COMPARE_NODE_FIELD(keys);
 	COMPARE_NODE_FIELD(exclusions);
 	COMPARE_NODE_FIELD(options);
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index c97532b348..8166bd35ea 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -497,6 +497,7 @@ makeColumnDef(const char *colname, Oid typeOid, int32 typmod, Oid collOid)
 	n->storage = 0;
 	n->raw_default = NULL;
 	n->cooked_default = NULL;
+	n->identity = ' ';
 	n->collClause = NULL;
 	n->collOid = collOid;
 	n->constraints = NIL;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 9fe98739c1..df723b41f3 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2587,6 +2587,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_CHAR_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_CHAR_FIELD(identity);
 	WRITE_NODE_FIELD(collClause);
 	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
@@ -2692,6 +2693,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
 	WRITE_NODE_FIELD(targetList);
+	WRITE_ENUM_FIELD(override, OverridingKind);
 	WRITE_NODE_FIELD(onConflict);
 	WRITE_NODE_FIELD(returningList);
 	WRITE_NODE_FIELD(groupClause);
@@ -3188,6 +3190,13 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_STRING_FIELD(cooked_expr);
 			break;
 
+		case CONSTR_IDENTITY:
+			appendStringInfoString(str, "IDENTITY");
+			WRITE_NODE_FIELD(raw_expr);
+			WRITE_STRING_FIELD(cooked_expr);
+			WRITE_CHAR_FIELD(generated_when);
+			break;
+
 		case CONSTR_CHECK:
 			appendStringInfoString(str, "CHECK");
 			WRITE_BOOL_FIELD(is_no_inherit);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 63f633634c..607168acfc 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -249,6 +249,7 @@ _readQuery(void)
 	READ_NODE_FIELD(rtable);
 	READ_NODE_FIELD(jointree);
 	READ_NODE_FIELD(targetList);
+	READ_ENUM_FIELD(override, OverridingKind);
 	READ_NODE_FIELD(onConflict);
 	READ_NODE_FIELD(returningList);
 	READ_NODE_FIELD(groupClause);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index a558083f43..70e49fde7b 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -464,6 +464,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
 	}
 
+	qry->override = stmt->override;
+
 	isOnConflictUpdate = (stmt->onConflictClause &&
 						stmt->onConflictClause->action == ONCONFLICT_UPDATE);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 08cf5b78f5..74856fc043 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -281,6 +281,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity partition_cmd
 %type <list>	alter_table_cmds alter_type_cmds
+%type <list>    alter_identity_column_option_list
+%type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -432,7 +434,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				select_offset_value2 opt_select_fetch_first_value
 %type <ival>	row_or_rows first_or_next
 
-%type <list>	OptSeqOptList SeqOptList
+%type <list>	OptSeqOptList SeqOptList OptParenthesizedSeqOptList
 %type <defelt>	SeqOptElem
 
 %type <istmt>	insert_rest
@@ -548,6 +550,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_frame_clause frame_extent frame_bound
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
+%type <ival>	generated_when override_kind
 %type <partspec>	PartitionSpec OptPartitionSpec
 %type <str>			part_strategy
 %type <partelem>	part_elem
@@ -610,7 +613,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
 	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
-	GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
+	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
 
 	HANDLER HAVING HEADER_P HOLD HOUR_P
 
@@ -634,7 +637,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	NULLS_P NUMERIC
 
 	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OPTIONS OR
-	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
+	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
 	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
@@ -705,6 +708,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * same as if they weren't keywords).  We need to do this for PARTITION,
  * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
  * so that they can follow a_expr without creating postfix-operator problems;
+ * for GENERATED so that it can follow b_expr;
  * and for NULL so that it can follow b_expr in ColQualList without creating
  * postfix-operator problems.
  *
@@ -723,7 +727,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * blame any funny behavior of UNBOUNDED on the SQL standard, though.
  */
 %nonassoc	UNBOUNDED		/* ideally should have same precedence as IDENT */
-%nonassoc	IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
+%nonassoc	IDENT GENERATED NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %left		'+' '-'
 %left		'*' '/' '%'
@@ -2091,6 +2095,40 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
+			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					Constraint *c = makeNode(Constraint);
+
+					c->contype = CONSTR_IDENTITY;
+					c->generated_when = $6;
+					c->options = $9;
+					c->location = @5;
+
+					n->subtype = AT_AddIdentity;
+					n->name = $3;
+					n->def = (Node *) c;
+
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
+			| ALTER opt_column ColId alter_identity_column_option_list
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->def = (Node *) $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
+			| ALTER opt_column ColId DROP IDENTITY_P
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
@@ -2528,6 +2566,38 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_option_list:
+			alter_identity_column_option
+				{ $$ = list_make1($1); }
+			| alter_identity_column_option_list alter_identity_column_option
+				{ $$ = lappend($1, $2); }
+		;
+
+alter_identity_column_option:
+			RESTART
+				{
+					$$ = makeDefElem("restart", NULL, @1);
+				}
+			| RESTART opt_with NumericOnly
+				{
+					$$ = makeDefElem("restart", (Node *)$3, @1);
+				}
+			| SET SeqOptElem
+				{
+					if (strcmp($2->defname, "restart") == 0 ||
+						strcmp($2->defname, "owned_by") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("sequence option \"%s\" not supported here", $2->defname),
+								 parser_errposition(@2)));
+					$$ = $2;
+				}
+			| SET GENERATED generated_when
+				{
+					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
+				}
+		;
+
 ForValues:
 			/* a LIST partition */
 			FOR VALUES IN_P '(' partbound_datum_list ')'
@@ -3178,6 +3248,7 @@ columnDef:	ColId Typename create_generic_options ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					n->fdwoptions = $3;
 					SplitColQualList($4, &n->constraints, &n->collClause,
@@ -3199,6 +3270,7 @@ columnOptions:	ColId WITH OPTIONS ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					SplitColQualList($4, &n->constraints, &n->collClause,
 									 yyscanner);
@@ -3311,6 +3383,15 @@ ColConstraintElem:
 					n->cooked_expr = NULL;
 					$$ = (Node *)n;
 				}
+			| GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					Constraint *n = makeNode(Constraint);
+					n->contype = CONSTR_IDENTITY;
+					n->generated_when = $2;
+					n->options = $5;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
 			| REFERENCES qualified_name opt_column_list key_match key_actions
 				{
 					Constraint *n = makeNode(Constraint);
@@ -3328,6 +3409,11 @@ ColConstraintElem:
 				}
 		;
 
+generated_when:
+			ALWAYS			{ $$ = CONSTR_GENERATED_ALWAYS; }
+			| BY DEFAULT	{ $$ = CONSTR_GENERATED_DEFAULT; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -3394,6 +3480,7 @@ TableLikeOptionList:
 TableLikeOption:
 				DEFAULTS			{ $$ = CREATE_TABLE_LIKE_DEFAULTS; }
 				| CONSTRAINTS		{ $$ = CREATE_TABLE_LIKE_CONSTRAINTS; }
+				| IDENTITY_P		{ $$ = CREATE_TABLE_LIKE_IDENTITY; }
 				| INDEXES			{ $$ = CREATE_TABLE_LIKE_INDEXES; }
 				| STORAGE			{ $$ = CREATE_TABLE_LIKE_STORAGE; }
 				| COMMENTS			{ $$ = CREATE_TABLE_LIKE_COMMENTS; }
@@ -3903,6 +3990,10 @@ OptSeqOptList: SeqOptList							{ $$ = $1; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+OptParenthesizedSeqOptList: '(' SeqOptList ')'		{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
@@ -3943,6 +4034,11 @@ SeqOptElem: CACHE NumericOnly
 				{
 					$$ = makeDefElem("owned_by", (Node *)$3, @1);
 				}
+			| SEQUENCE NAME_P any_name
+				{
+					/* not documented, only used by pg_dump */
+					$$ = makeDefElem("sequence_name", (Node *)$3, @1);
+				}
 			| START opt_with NumericOnly
 				{
 					$$ = makeDefElem("start", (Node *)$3, @1);
@@ -10070,12 +10166,26 @@ insert_rest:
 					$$->cols = NIL;
 					$$->selectStmt = $1;
 				}
+			| OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = NIL;
+					$$->override = $2;
+					$$->selectStmt = $4;
+				}
 			| '(' insert_column_list ')' SelectStmt
 				{
 					$$ = makeNode(InsertStmt);
 					$$->cols = $2;
 					$$->selectStmt = $4;
 				}
+			| '(' insert_column_list ')' OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = $2;
+					$$->override = $5;
+					$$->selectStmt = $7;
+				}
 			| DEFAULT VALUES
 				{
 					$$ = makeNode(InsertStmt);
@@ -10084,6 +10194,11 @@ insert_rest:
 				}
 		;
 
+override_kind:
+			USER		{ $$ = OVERRIDING_USER_VALUE; }
+			| SYSTEM_P	{ $$ = OVERRIDING_SYSTEM_VALUE; }
+		;
+
 insert_column_list:
 			insert_column_item
 					{ $$ = list_make1($1); }
@@ -11434,6 +11549,7 @@ TableFuncElement:	ColId Typename opt_collate_clause
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collClause = (CollateClause *) $3;
 					n->collOid = InvalidOid;
 					n->constraints = NIL;
@@ -14091,6 +14207,7 @@ unreserved_keyword:
 			| FORWARD
 			| FUNCTION
 			| FUNCTIONS
+			| GENERATED
 			| GLOBAL
 			| GRANTED
 			| HANDLER
@@ -14159,6 +14276,7 @@ unreserved_keyword:
 			| OPTIONS
 			| ORDINALITY
 			| OVER
+			| OVERRIDING
 			| OWNED
 			| OWNER
 			| PARALLEL
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 4f74208633..f301fa614e 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -42,6 +42,7 @@
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
@@ -356,6 +357,150 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	return result;
 }
 
+static void
+generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column, List *seqoptions, DependencyType deptype,
+						 char **snamespace_p, char **sname_p)
+{
+	ListCell   *option;
+	DefElem	   *nameEl = NULL;
+	Oid			snamespaceid;
+	char	   *snamespace;
+	char	   *sname;
+	CreateSeqStmt *seqstmt;
+	AlterSeqStmt *altseqstmt;
+	List	   *attnamelist;
+
+	/*
+	 * Determine namespace and name to use for the sequence.
+	 *
+	 * First, check if a sequence name was passed in as an option.  This is
+	 * used by pg_dump.  Else, generate a name.
+	 *
+	 * Although we use ChooseRelationName, it's not guaranteed that the
+	 * selected sequence name won't conflict; given sufficiently long
+	 * field names, two different serial columns in the same table could
+	 * be assigned the same sequence name, and we'd not notice since we
+	 * aren't creating the sequence quite yet.  In practice this seems
+	 * quite unlikely to be a problem, especially since few people would
+	 * need two serial columns in one table.
+	 */
+
+	foreach(option, seqoptions)
+	{
+		DefElem    *defel = (DefElem *) lfirst(option);
+
+		if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			if (nameEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			nameEl = defel;
+		}
+	}
+
+	if (nameEl)
+	{
+		RangeVar *rv = makeRangeVarFromNameList((List *) nameEl->arg);
+		snamespace = rv->schemaname;
+		sname = rv->relname;
+		list_delete_ptr(seqoptions, nameEl);
+	}
+	else
+	{
+		if (cxt->rel)
+			snamespaceid = RelationGetNamespace(cxt->rel);
+		else
+		{
+			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
+			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
+		}
+		snamespace = get_namespace_name(snamespaceid);
+		sname = ChooseRelationName(cxt->relation->relname,
+								   column->colname,
+								   "seq",
+								   snamespaceid);
+	}
+
+	ereport(DEBUG1,
+			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
+					cxt->stmtType, sname,
+					cxt->relation->relname, column->colname)));
+
+	/*
+	 * Build a CREATE SEQUENCE command to create the sequence object, and
+	 * add it to the list of things to be done before this CREATE/ALTER
+	 * TABLE.
+	 */
+	seqstmt = makeNode(CreateSeqStmt);
+	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->options = seqoptions;
+
+	/*
+	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
+	 * by the table's owner.  The current user might be someone else
+	 * (perhaps a superuser, or someone who's only a member of the owning
+	 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
+	 * and sequence have exactly the same owning role.
+	 */
+	if (cxt->rel)
+		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
+	else
+		seqstmt->ownerId = InvalidOid;
+
+	cxt->blist = lappend(cxt->blist, seqstmt);
+
+	/*
+	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
+	 * as owned by this column, and add it to the list of things to be
+	 * done after this CREATE/ALTER TABLE.
+	 */
+	altseqstmt = makeNode(AlterSeqStmt);
+	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	attnamelist = list_make3(makeString(snamespace),
+							 makeString(cxt->relation->relname),
+							 makeString(column->colname));
+	altseqstmt->options = list_make2(makeDefElem("owned_by",
+												 (Node *) attnamelist, -1),
+									 makeDefElem("deptype",
+												 (Node *) makeInteger(deptype), -1));
+
+	cxt->alist = lappend(cxt->alist, altseqstmt);
+
+	*snamespace_p = snamespace;
+	*sname_p = sname;
+}
+
+/*
+ * Create an expression tree representing the function call
+ * nextval('sequencename').  We cannot reduce the raw tree to cooked
+ * form until after the sequence is created, but there's no need to do
+ * so.
+ */
+static FuncCall *
+generateNextvalExpr(char *snamespace, char *sname)
+{
+	char	   *qstring;
+	A_Const    *snamenode;
+	TypeCast   *castnode;
+	FuncCall   *funccallnode;
+
+	qstring = quote_qualified_identifier(snamespace, sname);
+	snamenode = makeNode(A_Const);
+	snamenode->val.type = T_String;
+	snamenode->val.val.str = qstring;
+	snamenode->location = -1;
+	castnode = makeNode(TypeCast);
+	castnode->typeName = SystemTypeName("regclass");
+	castnode->arg = (Node *) snamenode;
+	castnode->location = -1;
+	funccallnode = makeFuncCall(SystemFuncName("nextval"),
+								list_make1(castnode),
+								-1);
+
+	return funccallnode;
+}
+
 /*
  * transformColumnDefinition -
  *		transform a single ColumnDef within CREATE TABLE
@@ -367,7 +512,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	bool		is_serial;
 	bool		saw_nullable;
 	bool		saw_default;
-	Constraint *constraint;
+	bool		saw_identity;
 	ListCell   *clist;
 
 	cxt->columns = lappend(cxt->columns, column);
@@ -422,110 +567,21 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	/* Special actions for SERIAL pseudo-types */
 	if (is_serial)
 	{
-		Oid			snamespaceid;
 		char	   *snamespace;
 		char	   *sname;
-		char	   *qstring;
-		A_Const    *snamenode;
-		TypeCast   *castnode;
-		FuncCall   *funccallnode;
-		CreateSeqStmt *seqstmt;
-		AlterSeqStmt *altseqstmt;
-		List	   *attnamelist;
-
-		/*
-		 * Determine namespace and name to use for the sequence.
-		 *
-		 * Although we use ChooseRelationName, it's not guaranteed that the
-		 * selected sequence name won't conflict; given sufficiently long
-		 * field names, two different serial columns in the same table could
-		 * be assigned the same sequence name, and we'd not notice since we
-		 * aren't creating the sequence quite yet.  In practice this seems
-		 * quite unlikely to be a problem, especially since few people would
-		 * need two serial columns in one table.
-		 */
-		if (cxt->rel)
-			snamespaceid = RelationGetNamespace(cxt->rel);
-		else
-		{
-			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
-			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
-		}
-		snamespace = get_namespace_name(snamespaceid);
-		sname = ChooseRelationName(cxt->relation->relname,
-								   column->colname,
-								   "seq",
-								   snamespaceid);
-
-		ereport(DEBUG1,
-				(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
-						cxt->stmtType, sname,
-						cxt->relation->relname, column->colname)));
-
-		/*
-		 * Build a CREATE SEQUENCE command to create the sequence object, and
-		 * add it to the list of things to be done before this CREATE/ALTER
-		 * TABLE.
-		 */
-		seqstmt = makeNode(CreateSeqStmt);
-		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = NIL;
-
-		/*
-		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
-		 * by the table's owner.  The current user might be someone else
-		 * (perhaps a superuser, or someone who's only a member of the owning
-		 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
-		 * and sequence have exactly the same owning role.
-		 */
-		if (cxt->rel)
-			seqstmt->ownerId = cxt->rel->rd_rel->relowner;
-		else
-			seqstmt->ownerId = InvalidOid;
-
-		cxt->blist = lappend(cxt->blist, seqstmt);
-
-		/*
-		 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
-		 * as owned by this column, and add it to the list of things to be
-		 * done after this CREATE/ALTER TABLE.
-		 */
-		altseqstmt = makeNode(AlterSeqStmt);
-		altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		attnamelist = list_make3(makeString(snamespace),
-								 makeString(cxt->relation->relname),
-								 makeString(column->colname));
-		altseqstmt->options = list_make1(makeDefElem("owned_by",
-												  (Node *) attnamelist, -1));
+		Constraint *constraint;
 
-		cxt->alist = lappend(cxt->alist, altseqstmt);
+		generateSerialExtraStmts(cxt, column, NIL, DEPENDENCY_AUTO, &snamespace, &sname);
 
 		/*
 		 * Create appropriate constraints for SERIAL.  We do this in full,
 		 * rather than shortcutting, so that we will detect any conflicting
 		 * constraints the user wrote (like a different DEFAULT).
-		 *
-		 * Create an expression tree representing the function call
-		 * nextval('sequencename').  We cannot reduce the raw tree to cooked
-		 * form until after the sequence is created, but there's no need to do
-		 * so.
 		 */
-		qstring = quote_qualified_identifier(snamespace, sname);
-		snamenode = makeNode(A_Const);
-		snamenode->val.type = T_String;
-		snamenode->val.val.str = qstring;
-		snamenode->location = -1;
-		castnode = makeNode(TypeCast);
-		castnode->typeName = SystemTypeName("regclass");
-		castnode->arg = (Node *) snamenode;
-		castnode->location = -1;
-		funccallnode = makeFuncCall(SystemFuncName("nextval"),
-									list_make1(castnode),
-									-1);
 		constraint = makeNode(Constraint);
 		constraint->contype = CONSTR_DEFAULT;
 		constraint->location = -1;
-		constraint->raw_expr = (Node *) funccallnode;
+		constraint->raw_expr = (Node *) generateNextvalExpr(snamespace, sname);
 		constraint->cooked_expr = NULL;
 		column->constraints = lappend(column->constraints, constraint);
 
@@ -540,9 +596,12 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
 	saw_nullable = false;
 	saw_default = false;
+	saw_identity = false;
 
 	foreach(clist, column->constraints)
 	{
+		Constraint *constraint;
+
 		constraint = lfirst(clist);
 		Assert(IsA(constraint, Constraint));
 
@@ -582,9 +641,43 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 												constraint->location)));
 				column->raw_default = constraint->raw_expr;
 				Assert(constraint->cooked_expr == NULL);
+				column->identity = ' ';
 				saw_default = true;
 				break;
 
+			case CONSTR_IDENTITY:
+			{
+				char	   *snamespace;
+				char	   *sname;
+				Type		ctype;
+				Oid			typeOid;
+
+				ctype = typenameType(cxt->pstate, column->typeName, NULL);
+				typeOid = HeapTupleGetOid(ctype);
+				ReleaseSysCache(ctype);
+
+				if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("identity column type must be smallint, integer, or bigint")));
+
+				if (saw_identity)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
+									column->colname, cxt->relation->relname),
+							 parser_errposition(cxt->pstate,
+												constraint->location)));
+
+				generateSerialExtraStmts(cxt, column, constraint->options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+				column->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+				Assert(constraint->cooked_expr == NULL);
+				column->identity = constraint->generated_when;
+				saw_identity = true;
+				column->is_not_null = TRUE;
+				break;
+			}
+
 			case CONSTR_CHECK:
 				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
 				break;
@@ -661,6 +754,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 					 constraint->contype);
 				break;
 		}
+
+		if (saw_default && saw_identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
+							column->colname, cxt->relation->relname),
+					 parser_errposition(cxt->pstate,
+										constraint->location)));
 	}
 
 	/*
@@ -890,6 +991,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		def->storage = 0;
 		def->raw_default = NULL;
 		def->cooked_default = NULL;
+		def->identity = ' ';
 		def->collClause = NULL;
 		def->collOid = attribute->attcollation;
 		def->constraints = NIL;
@@ -905,7 +1007,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		/*
 		 * Copy default, if present and the default has been requested
 		 */
-		if (attribute->atthasdef &&
+		if (attribute->atthasdef && attribute->attidentity == ' ' &&
 			(table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS))
 		{
 			Node	   *this_default = NULL;
@@ -933,6 +1035,30 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			def->cooked_default = this_default;
 		}
 
+		/*
+		 * Copy identity if requested
+		 */
+		if (attribute->attidentity != ' ' &&
+			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
+		{
+			List       *seqlist;
+			Oid         seq_relid;
+			List	   *seq_options;
+			char	   *snamespace;
+			char	   *sname;
+
+			/*
+			 * find sequence owned by old column; extract sequence parameters;
+			 * build new default and create sequence commands
+			 */
+			seqlist = getOwnedSequences(RelationGetRelid(relation), attribute->attnum);
+			seq_relid = linitial_oid(seqlist);
+			seq_options = sequence_options(seq_relid);
+			generateSerialExtraStmts(cxt, def, seq_options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+			def->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+			def->identity = attribute->attidentity;
+		}
+
 		/* Likewise, copy storage if requested */
 		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
 			def->storage = attribute->attstorage;
@@ -1109,6 +1235,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 		n->storage = 0;
 		n->raw_default = NULL;
 		n->cooked_default = NULL;
+		n->identity = ' ';
 		n->collClause = NULL;
 		n->collOid = attr->attcollation;
 		n->constraints = NIL;
@@ -2653,6 +2780,87 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 					break;
 				}
 
+			case AT_AddIdentity:
+				{
+					Constraint  *def = (Constraint *) cmd->def;
+					ColumnDef *newdef = makeNode(ColumnDef);
+					Oid			typeOid;
+					char	   *snamespace;
+					char	   *sname;
+
+					Assert(IsA(def, Constraint));
+
+					typeOid = get_atttype(relid, get_attnum(relid, cmd->name));
+					if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("identity column type must be smallint, integer, or bigint")));
+
+					newdef->colname = cmd->name;  // XXX before below FIXME
+					generateSerialExtraStmts(&cxt, newdef, def->options, DEPENDENCY_INTERNAL, &snamespace, &sname);
+					newdef->raw_default = (Node *) generateNextvalExpr(snamespace, sname);
+					newdef->identity = def->generated_when;
+
+					cmd->def = (Node *) newdef;
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_SetIdentity:
+				{
+					/*
+					 * Create an ALTER SEQUENCE statement for the internal
+					 * sequence of the identity column.
+					 */
+					ListCell   *lc;
+					List	   *newseqopts = NIL;
+					List	   *newdef = NIL;
+					List	   *seqlist;
+					AttrNumber	attnum;
+
+					/*
+					 * Split options into those handled by ALTER SEQUENCE and
+					 * those for ALTER TABLE proper.
+					 */
+					foreach(lc, (List *) cmd->def)
+					{
+						DefElem	   *def = (DefElem *) lfirst(lc);
+
+						if (strcmp(def->defname, "generated") == 0)
+							newdef = lappend(newdef, def);
+						else
+							newseqopts = lappend(newseqopts, def);
+					}
+
+					attnum = get_attnum(relid, cmd->name);
+
+					if (attnum)
+					{
+						seqlist = getOwnedSequences(relid, attnum);
+						if (seqlist)
+						{
+							AlterSeqStmt *seqstmt;
+							Oid			seq_relid;
+
+							seqstmt = makeNode(AlterSeqStmt);
+							seq_relid = linitial_oid(seqlist);
+							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															 get_rel_name(seq_relid), -1);
+							seqstmt->options = newseqopts;
+							seqstmt->missing_ok = false;
+
+							cxt.alist = lappend(cxt.alist, seqstmt);
+						}
+					}
+					/* If column was not found or did not own sequences, we
+					 * just let the ALTER TABLE command error out. */
+
+					cmd->def = (Node *) newdef;
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
 			case AT_AttachPartition:
 				{
 					PartitionCmd *partcmd = (PartitionCmd *) cmd->def;
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index bf4f098c15..5c9f3005e0 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -61,6 +61,7 @@ static Query *rewriteRuleAction(Query *parsetree,
 static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static List *rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list);
@@ -705,6 +706,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 static List *
 rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list)
@@ -785,6 +787,7 @@ rewriteTargetListIU(List *targetList,
 	for (attrno = 1; attrno <= numattrs; attrno++)
 	{
 		TargetEntry *new_tle = new_tles[attrno - 1];
+		bool	apply_default;
 
 		att_tup = target_relation->rd_att->attrs[attrno - 1];
 
@@ -797,8 +800,37 @@ rewriteTargetListIU(List *targetList,
 		 * it's an INSERT and there's no tlist entry for the column, or the
 		 * tlist entry is a DEFAULT placeholder node.
 		 */
-		if ((new_tle == NULL && commandType == CMD_INSERT) ||
-			(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
+		apply_default =((new_tle == NULL && commandType == CMD_INSERT) ||
+						(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
+
+		if (commandType == CMD_INSERT)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+			{
+				if (override != OVERRIDING_SYSTEM_VALUE)
+					ereport(ERROR,
+							(errcode(ERRCODE_GENERATED_ALWAYS),
+							 errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
+							 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+									   NameStr(att_tup->attname)),
+							 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
+			}
+
+			if (att_tup->attidentity == CONSTR_GENERATED_DEFAULT && override == OVERRIDING_USER_VALUE)
+				apply_default = true;
+		}
+
+		if (commandType == CMD_UPDATE)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+				ereport(ERROR,
+						(errcode(ERRCODE_GENERATED_ALWAYS),
+						 errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
+						 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+								   NameStr(att_tup->attname))));
+		}
+
+		if (apply_default)
 		{
 			Node	   *new_expr;
 
@@ -3233,6 +3265,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				/* Process the main targetlist ... */
 				parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
 													  parsetree->commandType,
+															parsetree->override,
 															rt_entry_relation,
 												   parsetree->resultRelation,
 															&attrnos);
@@ -3245,6 +3278,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->targetList =
 					rewriteTargetListIU(parsetree->targetList,
 										parsetree->commandType,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation, NULL);
 			}
@@ -3255,6 +3289,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->onConflict->onConflictSet =
 					rewriteTargetListIU(parsetree->onConflict->onConflictSet,
 										CMD_UPDATE,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation,
 										NULL);
@@ -3264,7 +3299,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 		{
 			parsetree->targetList =
 				rewriteTargetListIU(parsetree->targetList,
-									parsetree->commandType, rt_entry_relation,
+									parsetree->commandType,
+									parsetree->override,
+									rt_entry_relation,
 									parsetree->resultRelation, NULL);
 			rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
 		}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 4e2ba19d1b..13db529927 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5790,6 +5790,14 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (query->targetList)
 		appendStringInfoString(buf, ") ");
 
+	if (query->override)
+	{
+		if (query->override == OVERRIDING_SYSTEM_VALUE)
+			appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
+		else if (query->override == OVERRIDING_USER_VALUE)
+			appendStringInfoString(buf, "OVERRIDING USER VALUE ");
+	}
+
 	if (select_rte)
 	{
 		/* Add the SELECT */
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 13ae6add03..2d7cdaad8d 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -836,6 +836,27 @@ get_attnum(Oid relid, const char *attname)
 		return InvalidAttrNumber;
 }
 
+char
+get_attidentity(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		char			result;
+
+		result = att_tup->attidentity;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return 0;
+}
+
 /*
  * get_atttype
  *
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 2a6835991c..7a0c30442d 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -3259,6 +3259,7 @@ RelationBuildLocalRelation(const char *relname,
 	has_not_null = false;
 	for (i = 0; i < natts; i++)
 	{
+		rel->rd_att->attrs[i]->attidentity = tupDesc->attrs[i]->attidentity;
 		rel->rd_att->attrs[i]->attnotnull = tupDesc->attrs[i]->attnotnull;
 		has_not_null |= tupDesc->attrs[i]->attnotnull;
 	}
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index e7bdb925ac..2c5915beb0 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -326,6 +326,7 @@ Section: Class 42 - Syntax Error or Access Rule Violation
 42P21    E    ERRCODE_COLLATION_MISMATCH                                     collation_mismatch
 42P22    E    ERRCODE_INDETERMINATE_COLLATION                                indeterminate_collation
 42809    E    ERRCODE_WRONG_OBJECT_TYPE                                      wrong_object_type
+428C9    E    ERRCODE_GENERATED_ALWAYS                                       generated_always
 
 # Note: for ERRCODE purposes, we divide namable objects into these categories:
 # databases, schemas, prepared statements, cursors, tables, columns,
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e5545b31d4..6f02a214ca 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1885,6 +1885,9 @@ dumpTableData_insert(Archive *fout, void *dcontext)
 						appendPQExpBufferStr(insertStmt, ") ");
 					}
 
+					if (tbinfo->needs_override)
+						appendPQExpBufferStr(insertStmt, "OVERRIDING SYSTEM VALUE ");
+
 					appendPQExpBufferStr(insertStmt, "VALUES (");
 				}
 			}
@@ -4945,6 +4948,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_toastreloptions;
 	int			i_reloftype;
 	int			i_relpages;
+	int			i_is_identity_sequence;
 	int			i_changed_acl;
 
 	/* Make sure we are in proper schema */
@@ -5021,6 +5025,7 @@ getTables(Archive *fout, int *numTables)
 						  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 						  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "
 						  "tc.reloptions AS toast_reloptions, "
+						  "EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND objsubid = 0 AND refclassid = 'pg_attrdef'::regclass AND deptype = 'i') AS is_identity_sequence, "
 						  "EXISTS (SELECT 1 FROM pg_attribute at LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
 						  "AND pip.classoid = 'pg_class'::regclass "
@@ -5472,6 +5477,7 @@ getTables(Archive *fout, int *numTables)
 	i_checkoption = PQfnumber(res, "checkoption");
 	i_toastreloptions = PQfnumber(res, "toast_reloptions");
 	i_reloftype = PQfnumber(res, "reloftype");
+	i_is_identity_sequence = PQfnumber(res, "is_identity_sequence");
 	i_changed_acl = PQfnumber(res, "changed_acl");
 
 	if (dopt->lockWaitTimeout)
@@ -5572,6 +5578,8 @@ getTables(Archive *fout, int *numTables)
 		tblinfo[i].dummy_view = false;	/* might get set during sort */
 		tblinfo[i].postponed_def = false;		/* might get set during sort */
 
+		tblinfo[i].is_identity_sequence = (strcmp(PQgetvalue(res, i, i_is_identity_sequence), "t") == 0);
+
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
 		 * in schema before we get around to dumping them.
@@ -7125,6 +7133,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	int			i_typstorage;
 	int			i_attnotnull;
 	int			i_atthasdef;
+	int			i_attidentity;
 	int			i_attisdropped;
 	int			i_attlen;
 	int			i_attalign;
@@ -7167,7 +7176,34 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 
 		resetPQExpBuffer(q);
 
-		if (fout->remoteVersion >= 90200)
+		if (fout->remoteVersion >= 100000)
+		{
+			/*
+			 * attidentity is new in version 10.
+			 */
+			appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
+							  "a.attstattarget, a.attstorage, t.typstorage, "
+							  "a.attnotnull, a.atthasdef, a.attisdropped, "
+							  "a.attlen, a.attalign, a.attislocal, "
+				  "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname, "
+						"array_to_string(a.attoptions, ', ') AS attoptions, "
+							  "CASE WHEN a.attcollation <> t.typcollation "
+						   "THEN a.attcollation ELSE 0 END AS attcollation, "
+							  "a.attidentity, "
+							  "pg_catalog.array_to_string(ARRAY("
+							  "SELECT pg_catalog.quote_ident(option_name) || "
+							  "' ' || pg_catalog.quote_literal(option_value) "
+						"FROM pg_catalog.pg_options_to_table(attfdwoptions) "
+							  "ORDER BY option_name"
+							  "), E',\n    ') AS attfdwoptions "
+			 "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
+							  "ON a.atttypid = t.oid "
+							  "WHERE a.attrelid = '%u'::pg_catalog.oid "
+							  "AND a.attnum > 0::pg_catalog.int2 "
+							  "ORDER BY a.attrelid, a.attnum",
+							  tbinfo->dobj.catId.oid);
+		}
+		else if (fout->remoteVersion >= 90200)
 		{
 			/*
 			 * attfdwoptions is new in 9.2.
@@ -7266,6 +7302,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		i_typstorage = PQfnumber(res, "typstorage");
 		i_attnotnull = PQfnumber(res, "attnotnull");
 		i_atthasdef = PQfnumber(res, "atthasdef");
+		i_attidentity = PQfnumber(res, "attidentity");
 		i_attisdropped = PQfnumber(res, "attisdropped");
 		i_attlen = PQfnumber(res, "attlen");
 		i_attalign = PQfnumber(res, "attalign");
@@ -7281,6 +7318,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		tbinfo->attstattarget = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attstorage = (char *) pg_malloc(ntups * sizeof(char));
 		tbinfo->typstorage = (char *) pg_malloc(ntups * sizeof(char));
+		tbinfo->attidentity = (char *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attisdropped = (bool *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attlen = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attalign = (char *) pg_malloc(ntups * sizeof(char));
@@ -7305,6 +7343,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, j, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
+			tbinfo->attidentity[j] = *(PQgetvalue(res, j, i_attidentity));
+			tbinfo->needs_override = tbinfo->needs_override || (tbinfo->attidentity[j] == 'a');
 			tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
 			tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
 			tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
@@ -7350,6 +7390,9 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			{
 				int			adnum;
 
+				if (tbinfo->attidentity[j] != ' ')
+					continue;
+
 				adnum = atoi(PQgetvalue(res, j, 2));
 
 				if (adnum <= 0 || adnum > ntups)
@@ -15502,10 +15545,13 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
-					  fmtId(tbinfo->dobj.namespace->dobj.name));
-	appendPQExpBuffer(delqry, "%s;\n",
-					  fmtId(tbinfo->dobj.name));
+	if (!tbinfo->is_identity_sequence)
+	{
+		appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+		appendPQExpBuffer(delqry, "%s;\n",
+						  fmtId(tbinfo->dobj.name));
+	}
 
 	resetPQExpBuffer(query);
 
@@ -15517,9 +15563,27 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 												tbinfo->dobj.catId.oid);
 	}
 
-	appendPQExpBuffer(query,
-					  "CREATE SEQUENCE %s\n",
-					  fmtId(tbinfo->dobj.name));
+	if (tbinfo->is_identity_sequence)
+	{
+		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+
+		appendPQExpBuffer(query,
+						  "ALTER TABLE %s ",
+						  fmtId(owning_tab->dobj.name));
+		appendPQExpBuffer(query,
+						  "ALTER COLUMN %s ADD GENERATED ",
+						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
+		if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'a')
+			appendPQExpBuffer(query, "ALWAYS");
+		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'd')
+			appendPQExpBuffer(query, "BY DEFAULT");
+		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+						  fmtId(tbinfo->dobj.name));
+	}
+	else
+		appendPQExpBuffer(query,
+						  "CREATE SEQUENCE %s\n",
+						  fmtId(tbinfo->dobj.name));
 
 	if (fout->remoteVersion >= 80400)
 		appendPQExpBuffer(query, "    START WITH %s\n", startv);
@@ -15540,7 +15604,10 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "    CACHE %s%s",
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
-	appendPQExpBufferStr(query, ";\n");
+	if (tbinfo->is_identity_sequence)
+		appendPQExpBufferStr(query, "\n);\n");
+	else
+		appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
@@ -15573,7 +15640,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	 * We need not schema-qualify the table reference because both sequence
 	 * and table must be in the same schema.
 	 */
-	if (OidIsValid(tbinfo->owning_tab))
+	if (OidIsValid(tbinfo->owning_tab) && !tbinfo->is_identity_sequence)
 	{
 		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
 
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 395a9f3288..315a2fa7a4 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -284,6 +284,7 @@ typedef struct _tableInfo
 	/* these two are set only if table is a sequence owned by a column: */
 	Oid			owning_tab;		/* OID of table owning sequence */
 	int			owning_col;		/* attr # of column owning sequence */
+	bool		is_identity_sequence;
 	int			relpages;		/* table's size in pages (from pg_class) */
 
 	bool		interesting;	/* true if need to collect more data */
@@ -302,6 +303,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	char	   *attidentity;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
 	char	   *attalign;		/* attribute align, used by binary_upgrade */
 	bool	   *attislocal;		/* true if attr has local definition */
@@ -313,6 +315,7 @@ typedef struct _tableInfo
 	struct _attrDefInfo **attrdefs;		/* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
 	char	   *partkeydef;		/* partition key definition */
+	bool		needs_override;	/* has GENERATED ALWAYS AS IDENTITY */
 
 	/*
 	 * Stuff computed only for dumpable tables.
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index a582a37953..2f058bddeb 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -1582,6 +1582,10 @@ describeOneTableDetails(const char *schemaname,
 							 "   WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation");
 	else
 		appendPQExpBufferStr(&buf, "\n  NULL AS attcollation");
+	if (pset.sversion >= 100000)
+		appendPQExpBufferStr(&buf, ", a.attidentity");
+	else
+		appendPQExpBufferStr(&buf, ", NULL AS attidentity");
 	if (tableinfo.relkind == 'i')
 		appendPQExpBufferStr(&buf, ",\n  pg_catalog.pg_get_indexdef(a.attrelid, a.attnum, TRUE) AS indexdef");
 	else
@@ -1756,12 +1760,24 @@ describeOneTableDetails(const char *schemaname,
 		/* Collation, Nullable, Default */
 		if (show_column_details)
 		{
+			char   *identity;
+			char   *default_str = "";
+
 			printTableAddCell(&cont, PQgetvalue(res, i, 5), false, false);
 
 			printTableAddCell(&cont, strcmp(PQgetvalue(res, i, 3), "t") == 0 ? "not null" : "", false, false);
 
-			/* (note: above we cut off the 'default' string at 128) */
-			printTableAddCell(&cont, PQgetvalue(res, i, 2), false, false);
+			identity = PQgetvalue(res, i, 6);
+
+			if (identity[0] == ' ')
+				/* (note: above we cut off the 'default' string at 128) */
+				default_str = PQgetvalue(res, i, 2);
+			else if (identity[0] == 'a')
+				default_str = "generated always as identity";
+			else if (identity[0] == 'd')
+				default_str = "generated by default as identity";
+
+			printTableAddCell(&cont, default_str, false, false);
 		}
 
 		/* Value: for sequences only */
@@ -1770,16 +1786,16 @@ describeOneTableDetails(const char *schemaname,
 
 		/* Expression for index column */
 		if (tableinfo.relkind == 'i')
-			printTableAddCell(&cont, PQgetvalue(res, i, 6), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
 
 		/* FDW options for foreign table column, only for 9.2 or later */
 		if (tableinfo.relkind == 'f' && pset.sversion >= 90200)
-			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 8), false, false);
 
 		/* Storage and Description */
 		if (verbose)
 		{
-			int			firstvcol = 8;
+			int			firstvcol = 9;
 			char	   *storage = PQgetvalue(res, i, firstvcol);
 
 			/* these strings are literal in our syntax, so not translated. */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 02c8d60c29..4aaa9add9a 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1807,7 +1807,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> */
 	else if (Matches6("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny) ||
 			 Matches5("ALTER", "TABLE", MatchAny, "ALTER", MatchAny))
-		COMPLETE_WITH_LIST4("TYPE", "SET", "RESET", "DROP");
+		COMPLETE_WITH_LIST5("TYPE", "SET", "RESET", "ADD", "DROP");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
@@ -1823,7 +1823,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> DROP */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "DROP") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "DROP"))
-		COMPLETE_WITH_LIST2("DEFAULT", "NOT NULL");
+		COMPLETE_WITH_LIST3("DEFAULT", "IDENTITY", "NOT NULL");
 	else if (Matches4("ALTER", "TABLE", MatchAny, "CLUSTER"))
 		COMPLETE_WITH_CONST("ON");
 	else if (Matches5("ALTER", "TABLE", MatchAny, "CLUSTER", "ON"))
@@ -2769,17 +2769,25 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * Complete INSERT INTO <table> with "(" or "VALUES" or "SELECT" or
-	 * "TABLE" or "DEFAULT VALUES"
+	 * "TABLE" or "DEFAULT VALUES" or "OVERRIDING"
 	 */
 	else if (TailMatches3("INSERT", "INTO", MatchAny))
-		COMPLETE_WITH_LIST5("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES");
+		COMPLETE_WITH_LIST6("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES", "OVERRIDING");
 
 	/*
 	 * Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" or
-	 * "TABLE"
+	 * "TABLE" or "OVERRIDING"
 	 */
 	else if (TailMatches4("INSERT", "INTO", MatchAny, MatchAny) &&
 			 ends_with(prev_wd, ')'))
+		COMPLETE_WITH_LIST4("SELECT", "TABLE", "VALUES", "OVERRIDING");
+
+	/* Complete OVERRIDING */
+	else if (TailMatches1("OVERRIDING"))
+		COMPLETE_WITH_LIST2("SYSTEM VALUE", "USER VALUE");
+
+	/* Complete after OVERRIDING clause */
+	else if (TailMatches3("OVERRIDING", MatchAny, "VALUE"))
 		COMPLETE_WITH_LIST3("SELECT", "TABLE", "VALUES");
 
 	/* Insert an open parenthesis after "VALUES" */
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 45596abe76..24d9652f9c 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201612231
+#define CATALOG_VERSION_NO	201612235
 
 #endif
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index e8a302f2fd..44f7e21f71 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -238,7 +238,7 @@ extern bool sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId);
 
 extern void markSequenceUnowned(Oid seqId);
 
-extern List *getOwnedSequences(Oid relid);
+extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
 
 extern Oid	get_constraint_index(Oid constraintId);
 
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index 39d8eedb4e..6406b07599 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -133,6 +133,9 @@ CATALOG(pg_attribute,1249) BKI_BOOTSTRAP BKI_WITHOUT_OIDS BKI_ROWTYPE_OID(75) BK
 	/* Has DEFAULT value or not */
 	bool		atthasdef;
 
+	/* 'a', 'd', or ' ' */
+	char		attidentity;
+
 	/* Is dropped (ie, logically invisible) or not */
 	bool		attisdropped;
 
@@ -188,7 +191,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
-#define Natts_pg_attribute				21
+#define Natts_pg_attribute				22
 #define Anum_pg_attribute_attrelid		1
 #define Anum_pg_attribute_attname		2
 #define Anum_pg_attribute_atttypid		3
@@ -203,13 +206,14 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 #define Anum_pg_attribute_attalign		12
 #define Anum_pg_attribute_attnotnull	13
 #define Anum_pg_attribute_atthasdef		14
-#define Anum_pg_attribute_attisdropped	15
-#define Anum_pg_attribute_attislocal	16
-#define Anum_pg_attribute_attinhcount	17
-#define Anum_pg_attribute_attcollation	18
-#define Anum_pg_attribute_attacl		19
-#define Anum_pg_attribute_attoptions	20
-#define Anum_pg_attribute_attfdwoptions 21
+#define Anum_pg_attribute_attidentity	15
+#define Anum_pg_attribute_attisdropped	16
+#define Anum_pg_attribute_attislocal	17
+#define Anum_pg_attribute_attinhcount	18
+#define Anum_pg_attribute_attcollation	19
+#define Anum_pg_attribute_attacl		20
+#define Anum_pg_attribute_attoptions	21
+#define Anum_pg_attribute_attfdwoptions 22
 
 
 /* ----------------
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index a61b7a2917..f4a9488483 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -149,7 +149,7 @@ typedef FormData_pg_class *Form_pg_class;
  */
 DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 21 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
 DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 29 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 1fd75b216d..b58ab10c0f 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -58,6 +58,7 @@ extern Datum setval_oid(PG_FUNCTION_ARGS);
 extern Datum setval3_oid(PG_FUNCTION_ARGS);
 extern Datum lastval(PG_FUNCTION_ARGS);
 
+extern List *sequence_options(Oid relid);
 extern Datum pg_sequence_parameters(PG_FUNCTION_ARGS);
 extern Datum pg_sequence_last_value(PG_FUNCTION_ARGS);
 
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 9d8ef775e4..39e32189a8 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -25,6 +25,13 @@
 #include "nodes/primnodes.h"
 #include "nodes/value.h"
 
+typedef enum OverridingKind
+{
+	OVERRIDING_NOT_SET = 0,
+	OVERRIDING_USER_VALUE,
+	OVERRIDING_SYSTEM_VALUE
+} OverridingKind;
+
 /* Possible sources of a Query */
 typedef enum QuerySource
 {
@@ -131,6 +138,8 @@ typedef struct Query
 
 	List	   *targetList;		/* target list (of TargetEntry) */
 
+	OverridingKind override;	/* OVERRIDING clause */
+
 	OnConflictExpr *onConflict; /* ON CONFLICT DO [NOTHING | UPDATE] */
 
 	List	   *returningList;	/* return-values list (of TargetEntry) */
@@ -596,6 +605,7 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	char		identity;		/* attidentity setting */
 	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
@@ -617,9 +627,10 @@ typedef enum TableLikeOption
 {
 	CREATE_TABLE_LIKE_DEFAULTS = 1 << 0,
 	CREATE_TABLE_LIKE_CONSTRAINTS = 1 << 1,
-	CREATE_TABLE_LIKE_INDEXES = 1 << 2,
-	CREATE_TABLE_LIKE_STORAGE = 1 << 3,
-	CREATE_TABLE_LIKE_COMMENTS = 1 << 4,
+	CREATE_TABLE_LIKE_IDENTITY = 1 << 2,
+	CREATE_TABLE_LIKE_INDEXES = 1 << 3,
+	CREATE_TABLE_LIKE_STORAGE = 1 << 4,
+	CREATE_TABLE_LIKE_COMMENTS = 1 << 5,
 	CREATE_TABLE_LIKE_ALL = PG_INT32_MAX
 } TableLikeOption;
 
@@ -1328,6 +1339,7 @@ typedef struct InsertStmt
 	OnConflictClause *onConflictClause; /* ON CONFLICT clause */
 	List	   *returningList;	/* list of expressions to return */
 	WithClause *withClause;		/* WITH clause */
+	OverridingKind override;	/* OVERRIDING clause */
 } InsertStmt;
 
 /* ----------------------
@@ -1631,7 +1643,10 @@ typedef enum AlterTableType
 	AT_NoForceRowSecurity,		/* NO FORCE ROW SECURITY */
 	AT_GenericOptions,			/* OPTIONS (...) */
 	AT_AttachPartition,			/* ATTACH PARTITION */
-	AT_DetachPartition			/* DETACH PARTITION */
+	AT_DetachPartition,			/* DETACH PARTITION */
+	AT_AddIdentity,				/* ADD IDENTITY */
+	AT_SetIdentity,				/* SET identity column options */
+	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
@@ -1904,6 +1919,7 @@ typedef enum ConstrType			/* types of constraints */
 								 * expect it */
 	CONSTR_NOTNULL,
 	CONSTR_DEFAULT,
+	CONSTR_IDENTITY,
 	CONSTR_CHECK,
 	CONSTR_PRIMARY,
 	CONSTR_UNIQUE,
@@ -1915,6 +1931,9 @@ typedef enum ConstrType			/* types of constraints */
 	CONSTR_ATTR_IMMEDIATE
 } ConstrType;
 
+#define CONSTR_GENERATED_ALWAYS		'a'
+#define CONSTR_GENERATED_DEFAULT	'd'
+
 /* Foreign key action codes */
 #define FKCONSTR_ACTION_NOACTION	'a'
 #define FKCONSTR_ACTION_RESTRICT	'r'
@@ -1942,6 +1961,7 @@ typedef struct Constraint
 	bool		is_no_inherit;	/* is constraint non-inheritable? */
 	Node	   *raw_expr;		/* expr, as untransformed parse tree */
 	char	   *cooked_expr;	/* expr, as nodeToString representation */
+	char		generated_when;
 
 	/* Fields used for unique constraints (UNIQUE and PRIMARY KEY): */
 	List	   *keys;			/* String nodes naming referenced column(s) */
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 581ff6eedb..d522e89efe 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -173,6 +173,7 @@ PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
 PG_KEYWORD("full", FULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("function", FUNCTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("functions", FUNCTIONS, UNRESERVED_KEYWORD)
+PG_KEYWORD("generated", GENERATED, UNRESERVED_KEYWORD)
 PG_KEYWORD("global", GLOBAL, UNRESERVED_KEYWORD)
 PG_KEYWORD("grant", GRANT, RESERVED_KEYWORD)
 PG_KEYWORD("granted", GRANTED, UNRESERVED_KEYWORD)
@@ -285,6 +286,7 @@ PG_KEYWORD("outer", OUTER_P, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("over", OVER, UNRESERVED_KEYWORD)
 PG_KEYWORD("overlaps", OVERLAPS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("overlay", OVERLAY, COL_NAME_KEYWORD)
+PG_KEYWORD("overriding", OVERRIDING, UNRESERVED_KEYWORD)
 PG_KEYWORD("owned", OWNED, UNRESERVED_KEYWORD)
 PG_KEYWORD("owner", OWNER, UNRESERVED_KEYWORD)
 PG_KEYWORD("parallel", PARALLEL, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index dcb89807e9..573533b389 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -64,6 +64,7 @@ extern Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 extern char *get_attname(Oid relid, AttrNumber attnum);
 extern char *get_relid_attribute_name(Oid relid, AttrNumber attnum);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
+extern char	get_attidentity(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index a25b221703..3f405c94ce 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -66,6 +66,53 @@ SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y
 (2 rows)
 
 DROP TABLE inhg;
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+                     Table "public.test_like_id_1"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+ a | b  
+---+----
+ 1 | b1
+(1 row)
+
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+           Table "public.test_like_id_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           | not null | 
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, b2).
+SELECT * FROM test_like_id_2;  -- identity was not copied
+ a | b 
+---+---
+(0 rows)
+
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+                     Table "public.test_like_id_3"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+ a | b  
+---+----
+ 1 | b3
+(1 row)
+
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
new file mode 100644
index 0000000000..4b09a34e3a
--- /dev/null
+++ b/src/test/regress/expected/identity.out
@@ -0,0 +1,274 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest3" is already an identity column
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+ table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
+------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
+ itest1     | a           |                | NO          | YES         | BY DEFAULT          | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest1     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest2     | a           |                | NO          | YES         | ALWAYS              | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest2     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest3     | a           |                | NO          | YES         | BY DEFAULT          | 7              | 5                  | 9223372036854775807 | 1                | NO
+ itest3     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+(6 rows)
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+ sequence_name 
+---------------
+(0 rows)
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ERROR:  column "a" of relation "itest4" is already an identity column
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ERROR:  identity column type must be smallint, integer, or bigint
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+ERROR:  identity column type must be smallint, integer, or bigint
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+ERROR:  multiple identity specifications for column "a" of table "itest_err_2"
+LINE 1: ...E itest_err_2 (a int generated always as identity generated ...
+                                                             ^
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_3"
+LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau...
+                                                  ^
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_4"
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest1;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest2;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest3;
+ a  | b 
+----+---
+  7 | 
+ 12 | 
+(2 rows)
+
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+-- OVERRIDING tests
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+SELECT * FROM itest1;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+(3 rows)
+
+-- UPDATE tests
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+  a  |  b  
+-----+-----
+  10 | xyz
+   3 | xyz
+ 101 | 
+   4 | 
+(4 rows)
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+ERROR:  column "a" can only be updated to DEFAULT
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+ 10 | xyz
+  3 | 
+(3 rows)
+
+-- DROP IDENTITY tests
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is not an identity column
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, ).
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+   | 
+(3 rows)
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+ERROR:  relation "itest4_a_seq" does not exist
+LINE 1: SELECT sequence_name FROM itest4_a_seq;
+                                  ^
+-- test views
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+SELECT * FROM itestv10;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itestv11;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv10;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv11;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 11 | xyz
+(3 rows)
+
+-- various tests
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+ERROR:  column "a" of relation "itest1" is an identity column
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ERROR:  column "a" of relation "itest5" already has a default value
+-- not allowed for now
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;
+ERROR:  cannot alter data type of identity column "a"
+-- ALTER COLUMN
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+  a  | b 
+-----+---
+   1 | 
+ 100 | 
+ 102 | 
+(3 rows)
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+ table_name | column_name | is_identity | identity_generation 
+------------+-------------+-------------+---------------------
+ itest6     | a           | YES         | BY DEFAULT
+ itest6     | b           | NO          | 
+(2 rows)
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+ERROR:  column "b" of relation "itest6" is not an identity column
+-- inheritance
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+(1 row)
+
+-- inherit identity column not allowed
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+ERROR:  cannot inherit from table with identity column
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+NOTICE:  merging column "a" with inherited definition
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+ a 
+---
+ 1
+(1 row)
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+ table_name | column_name | is_nullable | is_identity | identity_generation 
+------------+-------------+-------------+-------------+---------------------
+ itest7     | a           | NO          | YES         | ALWAYS
+ itest7b    | a           | YES         | NO          | 
+ itest7c    | a           | NO          | YES         | ALWAYS
+(3 rows)
+
+CREATE TABLE itest7d (a int);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- fail
+ERROR:  cannot add identity to table that has child tables
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- fail
+ERROR:  cannot add identity column to table that has child tables
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index 5c5277e0f1..c76a21788f 100644
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -393,6 +393,36 @@ SELECT * FROM truncate_a;
   2 |  34
 (2 rows)
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
+TRUNCATE truncate_b;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 46
+ 47
+(2 rows)
+
+TRUNCATE truncate_b RESTART IDENTITY;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 8641769351..9ff4bd4357 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -108,6 +108,11 @@ test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combo
 # ----------
 test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml
 
+# ----------
+# Another group of parallel tests
+# ----------
+test: identity
+
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger
 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 835cf3556c..1f022aef94 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -161,6 +161,7 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
+test: identity
 test: polymorphism
 test: rowtypes
 test: returning
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 900ca804cb..557040bbe7 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -37,6 +37,20 @@ CREATE TABLE inhg (x text, LIKE inhx INCLUDING CONSTRAINTS, y text); /* Copies c
 SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y */
 DROP TABLE inhg;
 
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+SELECT * FROM test_like_id_2;  -- identity was not copied
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
+
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
new file mode 100644
index 0000000000..9bced8dc4c
--- /dev/null
+++ b/src/test/regress/sql/identity.sql
@@ -0,0 +1,162 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+
+SELECT * FROM itest1;
+SELECT * FROM itest2;
+SELECT * FROM itest3;
+SELECT * FROM itest4;
+
+
+-- OVERRIDING tests
+
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest1;
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest2;
+
+
+-- UPDATE tests
+
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+
+
+-- DROP IDENTITY tests
+
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+
+
+-- test views
+
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+
+SELECT * FROM itestv10;
+SELECT * FROM itestv11;
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv10;
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv11;
+
+
+-- various tests
+
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+
+-- not allowed for now
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;
+
+
+-- ALTER COLUMN
+
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+
+
+-- inheritance
+
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+
+-- inherit identity column not allowed
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+
+CREATE TABLE itest7d (a int);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- fail
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- fail
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index a3d6f5368f..1aab021dbb 100644
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -202,6 +202,24 @@ CREATE TABLE truncate_a (id serial,
 INSERT INTO truncate_a DEFAULT VALUES;
 SELECT * FROM truncate_a;
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b RESTART IDENTITY;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
-- 
2.11.0

From 7a49363d0e5793544f75f4b57bf6049ba84b6c67 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 28 Feb 2017 21:09:02 -0500
Subject: [PATCH v4] Identity columns

This is the SQL standard-conforming variant of PostgreSQL's serial
columns.  It also fixes a few usability issues that serial columns
have:

- CREATE TABLE / LIKE copies default but refers to same sequence
- cannot add/drop serialness with ALTER TABLE
- dropping default does not drop sequence
- need to grant separate privileges to sequence
- slight weirdnesses because serial is some kind of special macro
---
 doc/src/sgml/catalogs.sgml                      |  11 +
 doc/src/sgml/information_schema.sgml            |  11 +-
 doc/src/sgml/ref/alter_table.sgml               |  29 ++
 doc/src/sgml/ref/create_table.sgml              |  65 +++-
 doc/src/sgml/ref/insert.sgml                    |  41 +++
 src/backend/access/common/tupdesc.c             |   5 +
 src/backend/catalog/dependency.c                |   7 +
 src/backend/catalog/genbki.pl                   |   2 +
 src/backend/catalog/heap.c                      |  15 +-
 src/backend/catalog/index.c                     |   1 +
 src/backend/catalog/information_schema.sql      |  17 +-
 src/backend/catalog/pg_depend.c                 |  35 ++-
 src/backend/catalog/sql_features.txt            |  12 +-
 src/backend/commands/sequence.c                 |  87 +++++-
 src/backend/commands/tablecmds.c                | 263 +++++++++++++++-
 src/backend/executor/execQual.c                 |  21 ++
 src/backend/nodes/copyfuncs.c                   |  21 ++
 src/backend/nodes/equalfuncs.c                  |  16 +
 src/backend/nodes/makefuncs.c                   |   1 +
 src/backend/nodes/nodeFuncs.c                   |  11 +
 src/backend/nodes/outfuncs.c                    |   9 +
 src/backend/nodes/readfuncs.c                   |   1 +
 src/backend/parser/analyze.c                    |   2 +
 src/backend/parser/gram.y                       | 127 +++++++-
 src/backend/parser/parse_utilcmd.c              | 379 +++++++++++++++++++-----
 src/backend/rewrite/rewriteHandler.c            |  56 +++-
 src/backend/utils/adt/ruleutils.c               |   8 +
 src/backend/utils/cache/lsyscache.c             |  21 ++
 src/backend/utils/cache/relcache.c              |   1 +
 src/backend/utils/errcodes.txt                  |   1 +
 src/bin/pg_dump/pg_dump.c                       |  90 +++++-
 src/bin/pg_dump/pg_dump.h                       |   3 +
 src/bin/psql/describe.c                         |  26 +-
 src/bin/psql/tab-complete.c                     |  18 +-
 src/include/catalog/catversion.h                |   2 +-
 src/include/catalog/dependency.h                |   3 +-
 src/include/catalog/pg_attribute.h              |  20 +-
 src/include/catalog/pg_class.h                  |   2 +-
 src/include/commands/sequence.h                 |   2 +
 src/include/nodes/nodes.h                       |   1 +
 src/include/nodes/parsenodes.h                  |  28 +-
 src/include/nodes/primnodes.h                   |  14 +
 src/include/parser/kwlist.h                     |   2 +
 src/include/utils/lsyscache.h                   |   1 +
 src/test/regress/expected/create_table_like.out |  47 +++
 src/test/regress/expected/identity.out          | 306 +++++++++++++++++++
 src/test/regress/expected/sequence.out          |   4 +-
 src/test/regress/expected/truncate.out          |  30 ++
 src/test/regress/parallel_schedule              |   5 +
 src/test/regress/serial_schedule                |   1 +
 src/test/regress/sql/create_table_like.sql      |  14 +
 src/test/regress/sql/identity.sql               | 177 +++++++++++
 src/test/regress/sql/sequence.sql               |   2 +-
 src/test/regress/sql/truncate.sql               |  18 ++
 54 files changed, 1923 insertions(+), 169 deletions(-)
 create mode 100644 src/test/regress/expected/identity.out
 create mode 100644 src/test/regress/sql/identity.sql

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 96cb9185c2..0df8c3da79 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1120,6 +1120,17 @@ <title><structname>pg_attribute</> Columns</title>
      </row>
 
      <row>
+      <entry><structfield>attidentity</structfield></entry>
+      <entry><type>char</type></entry>
+      <entry></entry>
+      <entry>
+       If a space character, then not an identity column.  Otherwise,
+       <literal>a</literal> = generated always, <literal>d</literal> =
+       generated by default.
+      </entry>
+     </row>
+
+     <row>
       <entry><structfield>attisdropped</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index a3a19ce8ce..02f7927436 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -1583,13 +1583,20 @@ <title><literal>columns</literal> Columns</title>
      <row>
       <entry><literal>is_identity</literal></entry>
       <entry><type>yes_or_no</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>YES</literal>,
+       else <literal>NO</literal>.
+      </entry>
      </row>
 
      <row>
       <entry><literal>identity_generation</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>ALWAYS</literal>
+       or <literal>BY DEFAULT</literal>, reflecting the definition of the
+       column.
+      </entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index da431f8369..be1c7f33a9 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -46,6 +46,9 @@
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESET } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
@@ -180,6 +183,32 @@ <title>Description</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
+    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
+    <term><literal>DROP IDENTITY</literal></term>
+    <listitem>
+     <para>
+      These forms change whether a column is an identity column or change the
+      generation attribute of an existing identity column.
+      See <xref linkend="sql-createtable"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET <replaceable>sequence_option</replaceable></literal></term>
+    <term><literal>RESET</literal></term>
+    <listitem>
+     <para>
+      These forms alter the sequence that underlies an existing identity
+      column.  <replaceable>sequence_option</replaceable> is an option
+      supported by <xref linkend="sql-altersequence"> such
+      as <literal>INCREMENT BY</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>SET STATISTICS</literal></term>
     <listitem>
      <para>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index bb081ff86f..d808ad4d64 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -62,6 +62,7 @@
   NULL |
   CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
   REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
@@ -81,7 +82,7 @@
 
 <phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
 
-{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
+{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | IDENTITY | INDEXES | STORAGE | COMMENTS | ALL }
 
 <phrase>and <replaceable class="PARAMETER">partition_bound_spec</replaceable> is:</phrase>
 
@@ -412,6 +413,11 @@ <title>Parameters</title>
       Column <literal>STORAGE</> settings are also copied from parent tables.
      </para>
 
+     <para>
+      If a column in the parent table is an identity column, that property is
+      not inherited.  A column in the child table can be declared identity
+      column if desired.
+     </para>
     </listitem>
    </varlistentry>
 
@@ -481,6 +487,12 @@ <title>Parameters</title>
       the original and new tables.
      </para>
      <para>
+      Any identity specifications of copied column definitions will only be
+      copied if <literal>INCLUDING IDENTITY</literal> is specified.  A new
+      sequence is created for each identity column of the new table, separate
+      from the sequences associated with the old table.
+     </para>
+     <para>
       Not-null constraints are always copied to the new table.
       <literal>CHECK</literal> constraints will be copied only if
       <literal>INCLUDING CONSTRAINTS</literal> is specified.
@@ -512,7 +524,7 @@ <title>Parameters</title>
      </para>
      <para>
       <literal>INCLUDING ALL</literal> is an abbreviated form of
-      <literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
+      <literal>INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
      </para>
      <para>
       Note that unlike <literal>INHERITS</literal>, columns and
@@ -627,6 +639,37 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]</literal></term>
+    <listitem>
+     <para>
+      This clause creates the column as an <firstterm>identity
+      column</firstterm>.  It will have an implicit sequence attached to it
+      and the column in new rows will automatically have values from the
+      sequence assigned to it.
+     </para>
+
+     <para>
+      The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
+      determine how the sequence value is given precedence over a
+      user-specified value in an <command>INSERT</command> statement.
+      If <literal>ALWAYS</literal> is specified, a user-specified value is
+      only accepted if the <command>INSERT</command> statement
+      specifies <literal>OVERRIDING SYSTEM VALUE</literal>.  If <literal>BY
+      DEFAULT</literal> is specified, then the user-specified value takes
+      precedence.  See <xref linkend="sql-insert"> for details.  (In
+      the <command>COPY</command> command, user-specified values are always
+      used regardless of this setting.)
+     </para>
+
+     <para>
+      The optional <replaceable>sequence_options</replaceable> clause can be
+      used to override the options of the sequence.
+      See <xref linkend="sql-createsequence"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>UNIQUE</> (column constraint)</term>
     <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
 
@@ -1259,7 +1302,7 @@ <title>Notes</title>
 
     <para>
      Using OIDs in new applications is not recommended: where
-     possible, using a <literal>SERIAL</literal> or other sequence
+     possible, using an identity column or other sequence
      generator as the table's primary key is preferred. However, if
      your application does make use of OIDs to identify specific
      rows of a table, it is recommended to create a unique constraint
@@ -1319,7 +1362,7 @@ <title>Examples</title>
 );
 
 CREATE TABLE distributors (
-     did    integer PRIMARY KEY DEFAULT nextval('serial'),
+     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
      name   varchar(40) NOT NULL CHECK (name &lt;&gt; '')
 );
 </programlisting>
@@ -1734,6 +1777,20 @@ <title>Zero-column Tables</title>
   </refsect2>
 
   <refsect2>
+   <title>Multiple Identity Columns</title>
+
+   <para>
+    <productname>PostgreSQL</productname> allows a table to have more than one
+    identity column.  The standard specifies that a table can have at most one
+    identity column.  This is relaxed mainly to give more flexibility for
+    doing schema changes or migrations.  Note that
+    the <command>INSERT</command> command supports only one override clause
+    that applies to the entire statement, so having multiple identity columns
+    with different behaviors is not well supported.
+   </para>
+  </refsect2>
+
+  <refsect2>
    <title><literal>LIKE</> Clause</title>
 
    <para>
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 521216b5d5..95aa77b907 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -23,6 +23,7 @@
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
 INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replaceable class="parameter">alias</replaceable> ] [ ( <replaceable class="PARAMETER">column_name</replaceable> [, ...] ) ]
+    [ OVERRIDING { SYSTEM | USER} VALUE ]
     { DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
     [ ON CONFLICT [ <replaceable class="parameter">conflict_target</replaceable> ] <replaceable class="parameter">conflict_action</replaceable> ]
     [ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@@ -202,10 +203,43 @@ <title id="sql-inserting-params-title">Inserting</title>
      </varlistentry>
 
      <varlistentry>
+      <term><literal>OVERRIDING SYSTEM VALUE</literal></term>
+      <listitem>
+       <para>
+        Without this clause, it is an error to specify an explicit value
+        (other than <literal>DEFAULT</literal>) for an identity column defined
+        as <literal>GENERATED ALWAYS</literal>.  This clause overrides that
+        restriction.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>OVERRIDING USER VALUE</literal></term>
+      <listitem>
+       <para>
+        If this clause is specified, then any values supplied for identity
+        columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
+        and the default sequence-generated values are applied.
+       </para>
+
+       <para>
+        This clause is useful for example when copying values between tables.
+        Writing <literal>INSERT INTO tbl2 OVERRIDING USER VALUE SELECT * FROM
+        tbl1</literal> will copy from <literal>tbl1</literal> all columns that
+        are not identity columns in <literal>tbl2</literal> but will continue
+        the sequence counters for any identity columns.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>DEFAULT VALUES</literal></term>
       <listitem>
        <para>
         All columns will be filled with their default values.
+        (An <literal>OVERRIDING</literal> clause is not permitted in this
+        form.)
        </para>
       </listitem>
      </varlistentry>
@@ -711,6 +745,13 @@ <title>Compatibility</title>
   </para>
 
   <para>
+   The SQL standard specifies that <literal>OVERRIDING SYSTEM VALUE</literal>
+   can only be specified if an identity column that is generated always
+   exists.  PostgreSQL allows the clause in any case and ignores it if it is
+   not applicable.
+  </para>
+
+  <para>
    Possible limitations of the <replaceable
    class="PARAMETER">query</replaceable> clause are documented under
    <xref linkend="sql-select">.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 4e2ebe1ae7..8ef24fe978 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -150,6 +150,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 		desc->attrs[i]->attnotnull = false;
 		desc->attrs[i]->atthasdef = false;
+		desc->attrs[i]->attidentity = ' ';
 	}
 
 	desc->tdtypeid = tupdesc->tdtypeid;
@@ -257,6 +258,7 @@ TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 	/* since we're not copying constraints or defaults, clear these */
 	dst->attrs[dstAttno - 1]->attnotnull = false;
 	dst->attrs[dstAttno - 1]->atthasdef = false;
+	dst->attrs[dstAttno - 1]->attidentity = ' ';
 }
 
 /*
@@ -401,6 +403,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atthasdef != attr2->atthasdef)
 			return false;
+		if (attr1->attidentity != attr2->attidentity)
+			return false;
 		if (attr1->attisdropped != attr2->attisdropped)
 			return false;
 		if (attr1->attislocal != attr2->attislocal)
@@ -534,6 +538,7 @@ TupleDescInitEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = ' ';
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index fc088b2165..76e3c43ba6 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -1923,6 +1923,13 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* fall through to examine arguments */
 	}
+	else if (IsA(node, NextValueExpr))
+	{
+		NextValueExpr  *nve = (NextValueExpr *) node;
+
+		add_object_address(OCLASS_CLASS, nve->seqid, 0,
+						   context->addrs);
+	}
 
 	return expression_tree_walker(node, find_expr_references_walker,
 								  (void *) context);
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 079516ca2f..93c1274b7f 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -409,6 +409,7 @@ sub emit_pgattr_row
 		attcacheoff   => '-1',
 		atttypmod     => '-1',
 		atthasdef     => 'f',
+		attidentity   => "' '",
 		attisdropped  => 'f',
 		attislocal    => 't',
 		attinhcount   => '0',
@@ -425,6 +426,7 @@ sub bki_insert
 	my @attnames   = @_;
 	my $oid        = $row->{oid} ? "OID = $row->{oid} " : '';
 	my $bki_values = join ' ', map $row->{$_}, @attnames;
+	$bki_values =~ s/'/"/g;
 	printf BKI "insert %s( %s)\n", $oid, $bki_values;
 }
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 41c0056556..77efa1eeeb 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -142,37 +142,37 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
 static FormData_pg_attribute a1 = {
 	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
 	SelfItemPointerAttributeNumber, 0, -1, -1,
-	false, 'p', 's', true, false, false, true, 0
+	false, 'p', 's', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a2 = {
 	0, {"oid"}, OIDOID, 0, sizeof(Oid),
 	ObjectIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a3 = {
 	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
 	MinTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a4 = {
 	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
 	MinCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a5 = {
 	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
 	MaxTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static FormData_pg_attribute a6 = {
 	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
 	MaxCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 /*
@@ -184,7 +184,7 @@ static FormData_pg_attribute a6 = {
 static FormData_pg_attribute a7 = {
 	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
 	TableOidAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ' ', false, true, 0
 };
 
 static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
@@ -618,6 +618,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
 	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
 	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
+	values[Anum_pg_attribute_attidentity - 1] = CharGetDatum(new_attribute->attidentity);
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index f8d92145e8..e5a194b4b5 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -353,6 +353,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->attnotnull = false;
 			to->atthasdef = false;
+			to->attidentity = ' ';
 			to->attislocal = true;
 			to->attinhcount = 0;
 			to->attcollation = collationObjectId[i];
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index 51795cd6de..5bf434e976 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -727,13 +727,13 @@ CREATE VIEW columns AS
            CAST(a.attnum AS sql_identifier) AS dtd_identifier,
            CAST('NO' AS yes_or_no) AS is_self_referencing,
 
-           CAST('NO' AS yes_or_no) AS is_identity,
-           CAST(null AS character_data) AS identity_generation,
-           CAST(null AS character_data) AS identity_start,
-           CAST(null AS character_data) AS identity_increment,
-           CAST(null AS character_data) AS identity_maximum,
-           CAST(null AS character_data) AS identity_minimum,
-           CAST(null AS yes_or_no) AS identity_cycle,
+           CAST(CASE WHEN a.attidentity IN ('a', 'd') THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_identity,
+           CAST(CASE a.attidentity WHEN 'a' THEN 'ALWAYS' WHEN 'd' THEN 'BY DEFAULT' END AS character_data) AS identity_generation,
+           CAST(seq.seqstart AS character_data) AS identity_start,
+           CAST(seq.seqincrement AS character_data) AS identity_increment,
+           CAST(seq.seqmax AS character_data) AS identity_maximum,
+           CAST(seq.seqmin AS character_data) AS identity_minimum,
+           CAST(CASE WHEN seq.seqcycle THEN 'YES' ELSE 'NO' END AS yes_or_no) AS identity_cycle,
 
            CAST('NEVER' AS character_data) AS is_generated,
            CAST(null AS character_data) AS generation_expression,
@@ -750,6 +750,8 @@ CREATE VIEW columns AS
            ON (t.typtype = 'd' AND t.typbasetype = bt.oid)
          LEFT JOIN (pg_collation co JOIN pg_namespace nco ON (co.collnamespace = nco.oid))
            ON a.attcollation = co.oid AND (nco.nspname, co.collname) <> ('pg_catalog', 'default')
+         LEFT JOIN (pg_depend dep JOIN pg_sequence seq ON (dep.classid = 'pg_class'::regclass AND dep.objid = seq.seqrelid AND dep.deptype = 'i'))
+           ON (dep.refclassid = 'pg_class'::regclass AND dep.refobjid = c.oid AND dep.refobjsubid = a.attnum)
 
     WHERE (NOT pg_is_other_temp_schema(nc.oid))
 
@@ -1543,6 +1545,7 @@ CREATE VIEW sequences AS
     FROM pg_namespace nc, pg_class c, pg_sequence s
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
+          AND NOT EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND deptype = 'i')
           AND (NOT pg_is_other_temp_schema(nc.oid))
           AND c.oid = s.seqrelid
           AND (pg_has_role(c.relowner, 'USAGE')
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index d0ee851215..f4c7d5a80f 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -551,17 +551,20 @@ markSequenceUnowned(Oid seqId)
 {
 	deleteDependencyRecordsForClass(RelationRelationId, seqId,
 									RelationRelationId, DEPENDENCY_AUTO);
+	deleteDependencyRecordsForClass(RelationRelationId, seqId,
+									RelationRelationId, DEPENDENCY_INTERNAL);
 }
 
 /*
- * Collect a list of OIDs of all sequences owned by the specified relation.
+ * Collect a list of OIDs of all sequences owned by the specified relation,
+ * and column if specified.
  */
 List *
-getOwnedSequences(Oid relid)
+getOwnedSequences(Oid relid, AttrNumber attnum)
 {
 	List	   *result = NIL;
 	Relation	depRel;
-	ScanKeyData key[2];
+	ScanKeyData key[3];
 	SysScanDesc scan;
 	HeapTuple	tup;
 
@@ -575,23 +578,28 @@ getOwnedSequences(Oid relid)
 				Anum_pg_depend_refobjid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(relid));
+	if (attnum)
+		ScanKeyInit(&key[2],
+					Anum_pg_depend_refobjsubid,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(attnum));
 
 	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 2, key);
+							  NULL, attnum ? 3 : 2, key);
 
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
 		Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
 
 		/*
-		 * We assume any auto dependency of a sequence on a column must be
+		 * We assume any auto or internal dependency of a sequence on a column must be
 		 * what we are looking for.  (We need the relkind test because indexes
 		 * can also have auto dependencies on columns.)
 		 */
 		if (deprec->classid == RelationRelationId &&
 			deprec->objsubid == 0 &&
 			deprec->refobjsubid != 0 &&
-			deprec->deptype == DEPENDENCY_AUTO &&
+			(deprec->deptype == DEPENDENCY_AUTO || deprec->deptype == DEPENDENCY_INTERNAL) &&
 			get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
 		{
 			result = lappend_oid(result, deprec->objid);
@@ -605,6 +613,21 @@ getOwnedSequences(Oid relid)
 	return result;
 }
 
+/*
+ * Get owned sequence, error if not exactly one.
+ */
+Oid
+getOwnedSequence(Oid relid, AttrNumber attnum)
+{
+	List	   *seqlist = getOwnedSequences(relid, attnum);
+
+	if (list_length(seqlist) > 1)
+		elog(ERROR, "more than one owned sequence found");
+	else if (list_length(seqlist) < 1)
+		elog(ERROR, "no owned sequence found");
+	else
+		return linitial_oid(seqlist);
+}
 
 /*
  * get_constraint_index
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 8956ba9304..2821b9b702 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -200,7 +200,7 @@ F181	Multiple module support			NO
 F191	Referential delete actions			YES	
 F200	TRUNCATE TABLE statement			YES	
 F201	CAST function			YES	
-F202	TRUNCATE TABLE: identity column restart option			NO	
+F202	TRUNCATE TABLE: identity column restart option			YES	
 F221	Explicit defaults			YES	
 F222	INSERT statement: DEFAULT VALUES clause			YES	
 F231	Privilege tables			YES	
@@ -241,9 +241,9 @@ F381	Extended schema manipulation	02	ALTER TABLE statement: ADD CONSTRAINT claus
 F381	Extended schema manipulation	03	ALTER TABLE statement: DROP CONSTRAINT clause	YES	
 F382	Alter column data type			YES	
 F383	Set column not null clause			YES	
-F384	Drop identity property clause			NO	
+F384	Drop identity property clause			YES	
 F385	Drop column generation expression clause			NO	
-F386	Set identity column generation clause			NO	
+F386	Set identity column generation clause			YES	
 F391	Long identifiers			YES	
 F392	Unicode escapes in identifiers			YES	
 F393	Unicode escapes in literals			YES	
@@ -420,11 +420,11 @@ T152	DISTINCT predicate with negation			YES
 T171	LIKE clause in table definition			YES	
 T172	AS subquery clause in table definition			YES	
 T173	Extended LIKE clause in table definition			YES	
-T174	Identity columns			NO	
+T174	Identity columns			YES	
 T175	Generated columns			NO	
 T176	Sequence generator support			NO	
-T177	Sequence generator support: simple restart option			NO	
-T178	Identity columns:  simple restart option			NO	
+T177	Sequence generator support: simple restart option			YES	
+T178	Identity columns:  simple restart option			YES	
 T180	System-versioned tables			NO	
 T181	Application-time period tables			NO	
 T191	Referential action RESTRICT			YES	
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index e0df642254..52e1890346 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -93,7 +93,6 @@ static HTAB *seqhashtab = NULL; /* hash table for SeqTable items */
 static SeqTableData *last_used_seq = NULL;
 
 static void fill_seq_with_data(Relation rel, HeapTuple tuple);
-static int64 nextval_internal(Oid relid);
 static Relation open_share_lock(SeqTable seq);
 static void create_seq_hashtable(void);
 static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
@@ -101,9 +100,10 @@ static Form_pg_sequence_data read_seq_tuple(Relation rel,
 			   Buffer *buf, HeapTuple seqdatatuple);
 static void init_params(ParseState *pstate, List *options, bool isInit,
 						Form_pg_sequence seqform,
-						Form_pg_sequence_data seqdataform, List **owned_by);
+						Form_pg_sequence_data seqdataform, List **owned_by,
+						DependencyType *deptype);
 static void do_setval(Oid relid, int64 next, bool iscalled);
-static void process_owned_by(Relation seqrel, List *owned_by);
+static void process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype);
 
 
 /*
@@ -116,6 +116,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	FormData_pg_sequence seqform;
 	FormData_pg_sequence_data seqdataform;
 	List	   *owned_by;
+	DependencyType deptype;
 	CreateStmt *stmt = makeNode(CreateStmt);
 	Oid			seqoid;
 	ObjectAddress address;
@@ -153,7 +154,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	}
 
 	/* Check and set all option values */
-	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by);
+	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by, &deptype);
 
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
@@ -170,6 +171,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 		coldef->storage = 0;
 		coldef->raw_default = NULL;
 		coldef->cooked_default = NULL;
+		coldef->identity = ' ';
 		coldef->collClause = NULL;
 		coldef->collOid = InvalidOid;
 		coldef->constraints = NIL;
@@ -219,7 +221,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(rel, owned_by);
+		process_owned_by(rel, owned_by, deptype);
 
 	heap_close(rel, NoLock);
 
@@ -418,6 +420,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	Form_pg_sequence_data seqdata;
 	FormData_pg_sequence_data newseqdata;
 	List	   *owned_by;
+	DependencyType deptype;
 	ObjectAddress address;
 	Relation	rel;
 	HeapTuple	tuple;
@@ -455,7 +458,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	seqform = (Form_pg_sequence) GETSTRUCT(tuple);
 
 	/* Check and set new values */
-	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by);
+	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by, &deptype);
 
 	/* Clear local cache so that we don't think we have cached numbers */
 	/* Note that we do not change the currval() state */
@@ -498,7 +501,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(seqrel, owned_by);
+		process_owned_by(seqrel, owned_by, deptype);
 
 	InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
@@ -554,7 +557,7 @@ nextval(PG_FUNCTION_ARGS)
 	 */
 	relid = RangeVarGetRelid(sequence, NoLock, false);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
 Datum
@@ -562,11 +565,11 @@ nextval_oid(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
-static int64
-nextval_internal(Oid relid)
+int64
+nextval_internal(Oid relid, bool check_permissions)
 {
 	SeqTable	elm;
 	Relation	seqrel;
@@ -592,7 +595,8 @@ nextval_internal(Oid relid)
 	/* open and AccessShareLock sequence */
 	init_sequence(relid, &elm, &seqrel);
 
-	if (pg_class_aclcheck(elm->relid, GetUserId(),
+	if (check_permissions &&
+		pg_class_aclcheck(elm->relid, GetUserId(),
 						  ACL_USAGE | ACL_UPDATE) != ACLCHECK_OK)
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -1221,7 +1225,8 @@ read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
 static void
 init_params(ParseState *pstate, List *options, bool isInit,
 			Form_pg_sequence seqform,
-			Form_pg_sequence_data seqdataform, List **owned_by)
+			Form_pg_sequence_data seqdataform, List **owned_by,
+			DependencyType *deptype)
 {
 	DefElem    *as_type = NULL;
 	DefElem    *start_value = NULL;
@@ -1231,9 +1236,11 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	DefElem    *min_value = NULL;
 	DefElem    *cache_value = NULL;
 	DefElem    *is_cycled = NULL;
+	DefElem	   *deptype_el = NULL;
 	ListCell   *option;
 
 	*owned_by = NIL;
+	*deptype = DEPENDENCY_AUTO;
 
 	foreach(option, options)
 	{
@@ -1320,6 +1327,28 @@ init_params(ParseState *pstate, List *options, bool isInit,
 						 parser_errposition(pstate, defel->location)));
 			*owned_by = defGetQualifiedName(defel);
 		}
+		else if (strcmp(defel->defname, "deptype") == 0)
+		{
+			if (deptype_el)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options"),
+						 parser_errposition(pstate, defel->location)));
+			deptype_el = defel;
+			*deptype = intVal(deptype_el->arg);
+		}
+		else if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			/*
+			 * The parser allows this, but it is only for identity columns, in
+			 * which case it is filtered out in parse_utilcmd.c.  We only get
+			 * here if someone puts it into a CREATE SEQUENCE.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("invalid sequence option SEQUENCE NAME"),
+					 parser_errposition(pstate, defel->location)));
+		}
 		else
 			elog(ERROR, "option \"%s\" not recognized",
 				 defel->defname);
@@ -1565,7 +1594,7 @@ init_params(ParseState *pstate, List *options, bool isInit,
  * as the sequence.
  */
 static void
-process_owned_by(Relation seqrel, List *owned_by)
+process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype)
 {
 	int			nnames;
 	Relation	tablerel;
@@ -1601,6 +1630,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		/* Must be a regular or foreign table */
 		if (!(tablerel->rd_rel->relkind == RELKIND_RELATION ||
 			  tablerel->rd_rel->relkind == RELKIND_FOREIGN_TABLE ||
+			  tablerel->rd_rel->relkind == RELKIND_VIEW ||
 			  tablerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
@@ -1643,7 +1673,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		depobject.classId = RelationRelationId;
 		depobject.objectId = RelationGetRelid(seqrel);
 		depobject.objectSubId = 0;
-		recordDependencyOn(&depobject, &refobject, DEPENDENCY_AUTO);
+		recordDependencyOn(&depobject, &refobject, deptype);
 	}
 
 	/* Done, but hold lock until commit */
@@ -1653,6 +1683,33 @@ process_owned_by(Relation seqrel, List *owned_by)
 
 
 /*
+ * Return sequence parameters in a list of the form created by the parser.
+ */
+List *
+sequence_options(Oid relid)
+{
+	HeapTuple	pgstuple;
+	Form_pg_sequence pgsform;
+	List	   *options = NIL;
+
+	pgstuple = SearchSysCache1(SEQRELID, relid);
+	if (!HeapTupleIsValid(pgstuple))
+		elog(ERROR, "cache lookup failed for sequence %u", relid);
+	pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
+
+	options = lappend(options, makeDefElem("cache", (Node *) makeInteger(pgsform->seqcache), -1));
+	options = lappend(options, makeDefElem("cycle", (Node *) makeInteger(pgsform->seqcycle), -1));
+	options = lappend(options, makeDefElem("increment", (Node *) makeInteger(pgsform->seqincrement), -1));
+	options = lappend(options, makeDefElem("maxvalue", (Node *) makeInteger(pgsform->seqmax), -1));
+	options = lappend(options, makeDefElem("minvalue", (Node *) makeInteger(pgsform->seqmin), -1));
+	options = lappend(options, makeDefElem("start", (Node *) makeInteger(pgsform->seqstart), -1));
+
+	ReleaseSysCache(pgstuple);
+
+	return options;
+}
+
+/*
  * Return sequence parameters (formerly for use by information schema)
  */
 Datum
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 3cea220421..1ac6331c70 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -359,6 +359,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@@ -694,6 +699,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1279,7 +1287,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;
 
 			foreach(seqcell, seqlist)
@@ -2068,6 +2076,12 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   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;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@@ -3197,6 +3211,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -3415,6 +3432,8 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			pass = AT_PASS_ADD_COL;
 			break;
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
+		case AT_AddIdentity:
+		case AT_DropIdentity:
 
 			/*
 			 * We allow defaults on views so that INSERT into a view can have
@@ -3427,6 +3446,11 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			ATSimpleRecursion(wqueue, rel, cmd, recurse, lockmode);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATPrepDropNotNull(rel, recurse, recursing);
@@ -3752,6 +3776,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@@ -5102,6 +5135,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		elog(ERROR, "cache lookup failed for relation %u", myrelid);
 	relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
 
+	/*
+	 * Cannot add identity column if table has children, because identity does
+	 * not inherit.  (Adding column and identity separately will work.)
+	 */
+	if (colDef->identity != ' ' &&
+		recurse &&
+		find_inheritance_children(myrelid, NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot recursively add identity column to table that has child tables")));
+
 	/* skip if the name already exists and if_not_exists is true */
 	if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
 	{
@@ -5154,6 +5198,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = colDef->identity;
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@@ -5460,6 +5505,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		cdef->is_local = true;
 		cdef->is_not_null = true;
 		cdef->storage = 0;
+		cdef->identity = ' ';
 		cdef->location = -1;
 		cmd->def = (Node *) cdef;
 	}
@@ -5521,6 +5567,12 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Check that the attribute is not in a primary key
 	 *
@@ -5737,6 +5789,13 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ' ')
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel)),
+				 newDefault ? 0 : errhint("Use ALTER TABLE ... ALTER COLUMN ... DROP IDENTITY instead.")));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@@ -5772,6 +5831,208 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	ObjectAddress address;
+	ColumnDef  *cdef = castNode(ColumnDef, def);
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	/*
+	 * Creating a column as identity implies NOT NULL, so adding the identity
+	 * to an existing column that is not NOT NULL would create a state that
+	 * cannot be reproduced without contortions.
+	 */
+	if (!attTup->attnotnull)
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->attidentity != ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, castNode(List, def))
+	{
+		DefElem	   *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+	Oid			seqid;
+	ObjectAddress seqaddress;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ' ')
+		ereport(ERROR,
+				(errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = ' ';
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	/* drop the internal sequence */
+	seqid = getOwnedSequence(RelationGetRelid(rel), attnum);
+	deleteDependencyRecordsForClass(RelationRelationId, seqid,
+									RelationRelationId, DEPENDENCY_INTERNAL);
+	CommandCounterIncrement();
+	seqaddress.classId = RelationRelationId;
+	seqaddress.objectId = seqid;
+	seqaddress.objectSubId = 0;
+	performDeletion(&seqaddress, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET STATISTICS
  */
 static void
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 4566219ca8..685ea739f3 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -41,6 +41,7 @@
 #include "access/tupconvert.h"
 #include "catalog/objectaccess.h"
 #include "catalog/pg_type.h"
+#include "commands/sequence.h"
 #include "executor/execdebug.h"
 #include "executor/nodeSubplan.h"
 #include "funcapi.h"
@@ -182,6 +183,8 @@ static Datum ExecEvalArrayCoerceExpr(ArrayCoerceExprState *astate,
 						bool *isNull);
 static Datum ExecEvalCurrentOfExpr(ExprState *exprstate, ExprContext *econtext,
 					  bool *isNull);
+static Datum ExecEvalNextValueExpr(ExprState *exprstate, ExprContext *econtext,
+								   bool *isNull);
 static Datum ExecEvalGroupingFuncExpr(GroupingFuncExprState *gstate,
 						 ExprContext *econtext,
 						 bool *isNull);
@@ -4211,6 +4214,20 @@ ExecEvalCurrentOfExpr(ExprState *exprstate, ExprContext *econtext,
 
 
 /*
+ * ExecEvalNextValueExpr
+ */
+static Datum
+ExecEvalNextValueExpr(ExprState *exprstate, ExprContext *econtext,
+					  bool *isNull)
+{
+	NextValueExpr *nve = (NextValueExpr *) exprstate->expr;
+
+	*isNull = false;
+	return Int64GetDatum(nextval_internal(nve->seqid, false));
+}
+
+
+/*
  * ExecEvalExprSwitchContext
  *
  * Same as ExecEvalExpr, but get into the right allocation context explicitly.
@@ -4952,6 +4969,10 @@ ExecInitExpr(Expr *node, PlanState *parent)
 			state = makeNode(ExprState);
 			state->evalfunc = ExecEvalCurrentOfExpr;
 			break;
+		case T_NextValueExpr:
+			state = (ExprState *) makeNode(ExprState);
+			state->evalfunc = (ExprStateEvalFunc) ExecEvalNextValueExpr;
+			break;
 		case T_TargetEntry:
 			{
 				TargetEntry *tle = (TargetEntry *) node;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 05d8538717..6fc98ef1c4 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1905,6 +1905,20 @@ _copyCurrentOfExpr(const CurrentOfExpr *from)
 	return newnode;
 }
 
+ /*
+  * _copyNextValueExpr
+  */
+static NextValueExpr *
+_copyNextValueExpr(const NextValueExpr *from)
+{
+	NextValueExpr *newnode = makeNode(NextValueExpr);
+
+	COPY_SCALAR_FIELD(seqid);
+	COPY_SCALAR_FIELD(typeId);
+
+	return newnode;
+}
+
 /*
  * _copyInferenceElem
  */
@@ -2644,6 +2658,7 @@ _copyColumnDef(const ColumnDef *from)
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_SCALAR_FIELD(identity);
 	COPY_NODE_FIELD(collClause);
 	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
@@ -2666,6 +2681,7 @@ _copyConstraint(const Constraint *from)
 	COPY_SCALAR_FIELD(is_no_inherit);
 	COPY_NODE_FIELD(raw_expr);
 	COPY_STRING_FIELD(cooked_expr);
+	COPY_SCALAR_FIELD(generated_when);
 	COPY_NODE_FIELD(keys);
 	COPY_NODE_FIELD(exclusions);
 	COPY_NODE_FIELD(options);
@@ -2774,6 +2790,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
 	COPY_NODE_FIELD(targetList);
+	COPY_SCALAR_FIELD(override);
 	COPY_NODE_FIELD(onConflict);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(groupClause);
@@ -2817,6 +2834,7 @@ _copyInsertStmt(const InsertStmt *from)
 	COPY_NODE_FIELD(onConflictClause);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(withClause);
+	COPY_SCALAR_FIELD(override);
 
 	return newnode;
 }
@@ -4749,6 +4767,9 @@ copyObject(const void *from)
 		case T_CurrentOfExpr:
 			retval = _copyCurrentOfExpr(from);
 			break;
+		case T_NextValueExpr:
+			retval = _copyNextValueExpr(from);
+			break;
 		case T_InferenceElem:
 			retval = _copyInferenceElem(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index d595cd7481..3203cf1320 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -714,6 +714,15 @@ _equalCurrentOfExpr(const CurrentOfExpr *a, const CurrentOfExpr *b)
 }
 
 static bool
+_equalNextValueExpr(const NextValueExpr *a, const NextValueExpr *b)
+{
+	COMPARE_SCALAR_FIELD(seqid);
+	COMPARE_SCALAR_FIELD(typeId);
+
+	return true;
+}
+
+static bool
 _equalInferenceElem(const InferenceElem *a, const InferenceElem *b)
 {
 	COMPARE_NODE_FIELD(expr);
@@ -934,6 +943,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
 	COMPARE_NODE_FIELD(targetList);
+	COMPARE_SCALAR_FIELD(override);
 	COMPARE_NODE_FIELD(onConflict);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(groupClause);
@@ -973,6 +983,7 @@ _equalInsertStmt(const InsertStmt *a, const InsertStmt *b)
 	COMPARE_NODE_FIELD(onConflictClause);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(withClause);
+	COMPARE_SCALAR_FIELD(override);
 
 	return true;
 }
@@ -2455,6 +2466,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_SCALAR_FIELD(identity);
 	COMPARE_NODE_FIELD(collClause);
 	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
@@ -2475,6 +2487,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_SCALAR_FIELD(is_no_inherit);
 	COMPARE_NODE_FIELD(raw_expr);
 	COMPARE_STRING_FIELD(cooked_expr);
+	COMPARE_SCALAR_FIELD(generated_when);
 	COMPARE_NODE_FIELD(keys);
 	COMPARE_NODE_FIELD(exclusions);
 	COMPARE_NODE_FIELD(options);
@@ -3020,6 +3033,9 @@ equal(const void *a, const void *b)
 		case T_CurrentOfExpr:
 			retval = _equalCurrentOfExpr(a, b);
 			break;
+		case T_NextValueExpr:
+			retval = _equalNextValueExpr(a, b);
+			break;
 		case T_InferenceElem:
 			retval = _equalInferenceElem(a, b);
 			break;
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index 7586cce56a..22ab685a17 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -497,6 +497,7 @@ makeColumnDef(const char *colname, Oid typeOid, int32 typmod, Oid collOid)
 	n->storage = 0;
 	n->raw_default = NULL;
 	n->cooked_default = NULL;
+	n->identity = ' ';
 	n->collClause = NULL;
 	n->collOid = collOid;
 	n->constraints = NIL;
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 71b24a079c..b60e58698f 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -246,6 +246,9 @@ exprType(const Node *expr)
 		case T_CurrentOfExpr:
 			type = BOOLOID;
 			break;
+		case T_NextValueExpr:
+			type = ((const NextValueExpr *) expr)->typeId;
+			break;
 		case T_InferenceElem:
 			{
 				const InferenceElem *n = (const InferenceElem *) expr;
@@ -919,6 +922,9 @@ exprCollation(const Node *expr)
 		case T_CurrentOfExpr:
 			coll = InvalidOid;	/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			coll = InvalidOid;	/* result is always an integer type */
+			break;
 		case T_InferenceElem:
 			coll = exprCollation((Node *) ((const InferenceElem *) expr)->expr);
 			break;
@@ -1122,6 +1128,9 @@ exprSetCollation(Node *expr, Oid collation)
 		case T_CurrentOfExpr:
 			Assert(!OidIsValid(collation));		/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			Assert(!OidIsValid(collation));		/* result is always an integer type */
+			break;
 		default:
 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
 			break;
@@ -1878,6 +1887,7 @@ expression_tree_walker(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
@@ -2452,6 +2462,7 @@ expression_tree_mutator(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index b3802b4428..5041c887b2 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2614,6 +2614,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_CHAR_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_CHAR_FIELD(identity);
 	WRITE_NODE_FIELD(collClause);
 	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
@@ -2719,6 +2720,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
 	WRITE_NODE_FIELD(targetList);
+	WRITE_ENUM_FIELD(override, OverridingKind);
 	WRITE_NODE_FIELD(onConflict);
 	WRITE_NODE_FIELD(returningList);
 	WRITE_NODE_FIELD(groupClause);
@@ -3218,6 +3220,13 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_STRING_FIELD(cooked_expr);
 			break;
 
+		case CONSTR_IDENTITY:
+			appendStringInfoString(str, "IDENTITY");
+			WRITE_NODE_FIELD(raw_expr);
+			WRITE_STRING_FIELD(cooked_expr);
+			WRITE_CHAR_FIELD(generated_when);
+			break;
+
 		case CONSTR_CHECK:
 			appendStringInfoString(str, "CHECK");
 			WRITE_BOOL_FIELD(is_no_inherit);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index d2f69fe70b..034c736a3f 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -249,6 +249,7 @@ _readQuery(void)
 	READ_NODE_FIELD(rtable);
 	READ_NODE_FIELD(jointree);
 	READ_NODE_FIELD(targetList);
+	READ_ENUM_FIELD(override, OverridingKind);
 	READ_NODE_FIELD(onConflict);
 	READ_NODE_FIELD(returningList);
 	READ_NODE_FIELD(groupClause);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 796b5c9a5f..31d3f384bc 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -484,6 +484,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
 	}
 
+	qry->override = stmt->override;
+
 	isOnConflictUpdate = (stmt->onConflictClause &&
 						stmt->onConflictClause->action == ONCONFLICT_UPDATE);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e833b2eba5..ad4d7f0827 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -292,6 +292,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity partition_cmd
 %type <list>	alter_table_cmds alter_type_cmds
+%type <list>    alter_identity_column_option_list
+%type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -447,7 +449,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				select_offset_value2 opt_select_fetch_first_value
 %type <ival>	row_or_rows first_or_next
 
-%type <list>	OptSeqOptList SeqOptList
+%type <list>	OptSeqOptList SeqOptList OptParenthesizedSeqOptList
 %type <defelt>	SeqOptElem
 
 %type <istmt>	insert_rest
@@ -563,6 +565,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_frame_clause frame_extent frame_bound
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
+%type <ival>	generated_when override_kind
 %type <partspec>	PartitionSpec OptPartitionSpec
 %type <str>			part_strategy
 %type <partelem>	part_elem
@@ -625,7 +628,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
 	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
-	GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
+	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
 
 	HANDLER HAVING HEADER_P HOLD HOUR_P
 
@@ -649,7 +652,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	NULLS_P NUMERIC
 
 	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OPTIONS OR
-	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
+	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
 	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
@@ -720,6 +723,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * same as if they weren't keywords).  We need to do this for PARTITION,
  * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
  * so that they can follow a_expr without creating postfix-operator problems;
+ * for GENERATED so that it can follow b_expr;
  * and for NULL so that it can follow b_expr in ColQualList without creating
  * postfix-operator problems.
  *
@@ -738,7 +742,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * blame any funny behavior of UNBOUNDED on the SQL standard, though.
  */
 %nonassoc	UNBOUNDED		/* ideally should have same precedence as IDENT */
-%nonassoc	IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
+%nonassoc	IDENT GENERATED NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %left		'+' '-'
 %left		'*' '/' '%'
@@ -2125,6 +2129,40 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
+			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					Constraint *c = makeNode(Constraint);
+
+					c->contype = CONSTR_IDENTITY;
+					c->generated_when = $6;
+					c->options = $9;
+					c->location = @5;
+
+					n->subtype = AT_AddIdentity;
+					n->name = $3;
+					n->def = (Node *) c;
+
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
+			| ALTER opt_column ColId alter_identity_column_option_list
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->def = (Node *) $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
+			| ALTER opt_column ColId DROP IDENTITY_P
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
@@ -2562,6 +2600,39 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_option_list:
+			alter_identity_column_option
+				{ $$ = list_make1($1); }
+			| alter_identity_column_option_list alter_identity_column_option
+				{ $$ = lappend($1, $2); }
+		;
+
+alter_identity_column_option:
+			RESTART
+				{
+					$$ = makeDefElem("restart", NULL, @1);
+				}
+			| RESTART opt_with NumericOnly
+				{
+					$$ = makeDefElem("restart", (Node *)$3, @1);
+				}
+			| SET SeqOptElem
+				{
+					if (strcmp($2->defname, "as") == 0 ||
+						strcmp($2->defname, "restart") == 0 ||
+						strcmp($2->defname, "owned_by") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("sequence option \"%s\" not supported here", $2->defname),
+								 parser_errposition(@2)));
+					$$ = $2;
+				}
+			| SET GENERATED generated_when
+				{
+					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
+				}
+		;
+
 ForValues:
 			/* a LIST partition */
 			FOR VALUES IN_P '(' partbound_datum_list ')'
@@ -3212,6 +3283,7 @@ columnDef:	ColId Typename create_generic_options ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					n->fdwoptions = $3;
 					SplitColQualList($4, &n->constraints, &n->collClause,
@@ -3233,6 +3305,7 @@ columnOptions:	ColId WITH OPTIONS ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collOid = InvalidOid;
 					SplitColQualList($4, &n->constraints, &n->collClause,
 									 yyscanner);
@@ -3344,6 +3417,15 @@ ColConstraintElem:
 					n->cooked_expr = NULL;
 					$$ = (Node *)n;
 				}
+			| GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					Constraint *n = makeNode(Constraint);
+					n->contype = CONSTR_IDENTITY;
+					n->generated_when = $2;
+					n->options = $5;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
 			| REFERENCES qualified_name opt_column_list key_match key_actions
 				{
 					Constraint *n = makeNode(Constraint);
@@ -3361,6 +3443,11 @@ ColConstraintElem:
 				}
 		;
 
+generated_when:
+			ALWAYS			{ $$ = CONSTR_GENERATED_ALWAYS; }
+			| BY DEFAULT	{ $$ = CONSTR_GENERATED_DEFAULT; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -3427,6 +3514,7 @@ TableLikeOptionList:
 TableLikeOption:
 				DEFAULTS			{ $$ = CREATE_TABLE_LIKE_DEFAULTS; }
 				| CONSTRAINTS		{ $$ = CREATE_TABLE_LIKE_CONSTRAINTS; }
+				| IDENTITY_P		{ $$ = CREATE_TABLE_LIKE_IDENTITY; }
 				| INDEXES			{ $$ = CREATE_TABLE_LIKE_INDEXES; }
 				| STORAGE			{ $$ = CREATE_TABLE_LIKE_STORAGE; }
 				| COMMENTS			{ $$ = CREATE_TABLE_LIKE_COMMENTS; }
@@ -3935,6 +4023,10 @@ OptSeqOptList: SeqOptList							{ $$ = $1; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+OptParenthesizedSeqOptList: '(' SeqOptList ')'		{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
@@ -3979,6 +4071,11 @@ SeqOptElem: AS SimpleTypename
 				{
 					$$ = makeDefElem("owned_by", (Node *)$3, @1);
 				}
+			| SEQUENCE NAME_P any_name
+				{
+					/* not documented, only used by pg_dump */
+					$$ = makeDefElem("sequence_name", (Node *)$3, @1);
+				}
 			| START opt_with NumericOnly
 				{
 					$$ = makeDefElem("start", (Node *)$3, @1);
@@ -10350,12 +10447,26 @@ insert_rest:
 					$$->cols = NIL;
 					$$->selectStmt = $1;
 				}
+			| OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = NIL;
+					$$->override = $2;
+					$$->selectStmt = $4;
+				}
 			| '(' insert_column_list ')' SelectStmt
 				{
 					$$ = makeNode(InsertStmt);
 					$$->cols = $2;
 					$$->selectStmt = $4;
 				}
+			| '(' insert_column_list ')' OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = $2;
+					$$->override = $5;
+					$$->selectStmt = $7;
+				}
 			| DEFAULT VALUES
 				{
 					$$ = makeNode(InsertStmt);
@@ -10364,6 +10475,11 @@ insert_rest:
 				}
 		;
 
+override_kind:
+			USER		{ $$ = OVERRIDING_USER_VALUE; }
+			| SYSTEM_P	{ $$ = OVERRIDING_SYSTEM_VALUE; }
+		;
+
 insert_column_list:
 			insert_column_item
 					{ $$ = list_make1($1); }
@@ -11714,6 +11830,7 @@ TableFuncElement:	ColId Typename opt_collate_clause
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ' ';
 					n->collClause = (CollateClause *) $3;
 					n->collOid = InvalidOid;
 					n->constraints = NIL;
@@ -14374,6 +14491,7 @@ unreserved_keyword:
 			| FORWARD
 			| FUNCTION
 			| FUNCTIONS
+			| GENERATED
 			| GLOBAL
 			| GRANTED
 			| HANDLER
@@ -14442,6 +14560,7 @@ unreserved_keyword:
 			| OPTIONS
 			| ORDINALITY
 			| OVER
+			| OVERRIDING
 			| OWNED
 			| OWNER
 			| PARALLEL
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index ff2bab6551..9e9b00ee5c 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -42,6 +42,7 @@
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
@@ -356,6 +357,130 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	return result;
 }
 
+static void
+generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
+						 Oid seqtypid, List *seqoptions, DependencyType deptype,
+						 char **snamespace_p, char **sname_p)
+{
+	ListCell   *option;
+	DefElem	   *nameEl = NULL;
+	Oid			snamespaceid;
+	char	   *snamespace;
+	char	   *sname;
+	CreateSeqStmt *seqstmt;
+	AlterSeqStmt *altseqstmt;
+	List	   *attnamelist;
+
+	/*
+	 * Determine namespace and name to use for the sequence.
+	 *
+	 * First, check if a sequence name was passed in as an option.  This is
+	 * used by pg_dump.  Else, generate a name.
+	 *
+	 * Although we use ChooseRelationName, it's not guaranteed that the
+	 * selected sequence name won't conflict; given sufficiently long
+	 * field names, two different serial columns in the same table could
+	 * be assigned the same sequence name, and we'd not notice since we
+	 * aren't creating the sequence quite yet.  In practice this seems
+	 * quite unlikely to be a problem, especially since few people would
+	 * need two serial columns in one table.
+	 */
+
+	foreach(option, seqoptions)
+	{
+		DefElem    *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			if (nameEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			nameEl = defel;
+		}
+	}
+
+	if (nameEl)
+	{
+		RangeVar *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));
+		snamespace = rv->schemaname;
+		sname = rv->relname;
+		seqoptions = list_delete_ptr(seqoptions, nameEl);
+	}
+	else
+	{
+		if (cxt->rel)
+			snamespaceid = RelationGetNamespace(cxt->rel);
+		else
+		{
+			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
+			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
+		}
+		snamespace = get_namespace_name(snamespaceid);
+		sname = ChooseRelationName(cxt->relation->relname,
+								   column->colname,
+								   "seq",
+								   snamespaceid);
+	}
+
+	ereport(DEBUG1,
+			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
+					cxt->stmtType, sname,
+					cxt->relation->relname, column->colname)));
+
+	/*
+	 * Build a CREATE SEQUENCE command to create the sequence object, and
+	 * add it to the list of things to be done before this CREATE/ALTER
+	 * TABLE.
+	 */
+	seqstmt = makeNode(CreateSeqStmt);
+	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->options = seqoptions;
+	/*
+	 * If a sequence data type was specified, add it to the options.  Prepend
+	 * to the list rather than append; in case a user supplied their own AS
+	 * clause, the "redundant options" error will point to their occurrence,
+	 * not our synthetic one.
+	 */
+	if (seqtypid)
+		seqstmt->options = lcons(makeDefElem("as", (Node *) makeTypeNameFromOid(seqtypid, -1), -1),
+								 seqstmt->options);
+
+	/*
+	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
+	 * by the table's owner.  The current user might be someone else
+	 * (perhaps a superuser, or someone who's only a member of the owning
+	 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
+	 * and sequence have exactly the same owning role.
+	 */
+	if (cxt->rel)
+		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
+	else
+		seqstmt->ownerId = InvalidOid;
+
+	cxt->blist = lappend(cxt->blist, seqstmt);
+
+	/*
+	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
+	 * as owned by this column, and add it to the list of things to be
+	 * done after this CREATE/ALTER TABLE.
+	 */
+	altseqstmt = makeNode(AlterSeqStmt);
+	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	attnamelist = list_make3(makeString(snamespace),
+							 makeString(cxt->relation->relname),
+							 makeString(column->colname));
+	altseqstmt->options = list_make2(makeDefElem("owned_by",
+												 (Node *) attnamelist, -1),
+									 makeDefElem("deptype",
+												 (Node *) makeInteger(deptype), -1));
+
+	cxt->alist = lappend(cxt->alist, altseqstmt);
+
+	*snamespace_p = snamespace;
+	*sname_p = sname;
+}
+
 /*
  * transformColumnDefinition -
  *		transform a single ColumnDef within CREATE TABLE
@@ -367,7 +492,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	bool		is_serial;
 	bool		saw_nullable;
 	bool		saw_default;
-	Constraint *constraint;
+	bool		saw_identity;
 	ListCell   *clist;
 
 	cxt->columns = lappend(cxt->columns, column);
@@ -422,83 +547,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	/* Special actions for SERIAL pseudo-types */
 	if (is_serial)
 	{
-		Oid			snamespaceid;
 		char	   *snamespace;
 		char	   *sname;
 		char	   *qstring;
 		A_Const    *snamenode;
 		TypeCast   *castnode;
 		FuncCall   *funccallnode;
-		CreateSeqStmt *seqstmt;
-		AlterSeqStmt *altseqstmt;
-		List	   *attnamelist;
-
-		/*
-		 * Determine namespace and name to use for the sequence.
-		 *
-		 * Although we use ChooseRelationName, it's not guaranteed that the
-		 * selected sequence name won't conflict; given sufficiently long
-		 * field names, two different serial columns in the same table could
-		 * be assigned the same sequence name, and we'd not notice since we
-		 * aren't creating the sequence quite yet.  In practice this seems
-		 * quite unlikely to be a problem, especially since few people would
-		 * need two serial columns in one table.
-		 */
-		if (cxt->rel)
-			snamespaceid = RelationGetNamespace(cxt->rel);
-		else
-		{
-			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
-			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
-		}
-		snamespace = get_namespace_name(snamespaceid);
-		sname = ChooseRelationName(cxt->relation->relname,
-								   column->colname,
-								   "seq",
-								   snamespaceid);
-
-		ereport(DEBUG1,
-				(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
-						cxt->stmtType, sname,
-						cxt->relation->relname, column->colname)));
-
-		/*
-		 * Build a CREATE SEQUENCE command to create the sequence object, and
-		 * add it to the list of things to be done before this CREATE/ALTER
-		 * TABLE.
-		 */
-		seqstmt = makeNode(CreateSeqStmt);
-		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(column->typeName->typeOid, -1), -1));
+		Constraint *constraint;
 
-		/*
-		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
-		 * by the table's owner.  The current user might be someone else
-		 * (perhaps a superuser, or someone who's only a member of the owning
-		 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
-		 * and sequence have exactly the same owning role.
-		 */
-		if (cxt->rel)
-			seqstmt->ownerId = cxt->rel->rd_rel->relowner;
-		else
-			seqstmt->ownerId = InvalidOid;
-
-		cxt->blist = lappend(cxt->blist, seqstmt);
-
-		/*
-		 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
-		 * as owned by this column, and add it to the list of things to be
-		 * done after this CREATE/ALTER TABLE.
-		 */
-		altseqstmt = makeNode(AlterSeqStmt);
-		altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		attnamelist = list_make3(makeString(snamespace),
-								 makeString(cxt->relation->relname),
-								 makeString(column->colname));
-		altseqstmt->options = list_make1(makeDefElem("owned_by",
-												  (Node *) attnamelist, -1));
-
-		cxt->alist = lappend(cxt->alist, altseqstmt);
+		generateSerialExtraStmts(cxt, column,
+								 column->typeName->typeOid, NIL, DEPENDENCY_AUTO,
+								 &snamespace, &sname);
 
 		/*
 		 * Create appropriate constraints for SERIAL.  We do this in full,
@@ -540,10 +599,11 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
 	saw_nullable = false;
 	saw_default = false;
+	saw_identity = false;
 
 	foreach(clist, column->constraints)
 	{
-		constraint = castNode(Constraint, lfirst(clist));
+		Constraint *constraint = castNode(Constraint, lfirst(clist));
 
 		switch (constraint->contype)
 		{
@@ -581,9 +641,44 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 												constraint->location)));
 				column->raw_default = constraint->raw_expr;
 				Assert(constraint->cooked_expr == NULL);
+				column->identity = ' ';
 				saw_default = true;
 				break;
 
+			case CONSTR_IDENTITY:
+			{
+				char	   *snamespace;
+				char	   *sname;
+				Type		ctype;
+				Oid			typeOid;
+
+				ctype = typenameType(cxt->pstate, column->typeName, NULL);
+				typeOid = HeapTupleGetOid(ctype);
+				ReleaseSysCache(ctype);
+
+				if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("identity column type must be smallint, integer, or bigint")));
+
+				if (saw_identity)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
+									column->colname, cxt->relation->relname),
+							 parser_errposition(cxt->pstate,
+												constraint->location)));
+
+				generateSerialExtraStmts(cxt, column,
+										 typeOid, constraint->options, DEPENDENCY_INTERNAL,
+										 &snamespace, &sname);
+
+				column->identity = constraint->generated_when;
+				saw_identity = true;
+				column->is_not_null = TRUE;
+				break;
+			}
+
 			case CONSTR_CHECK:
 				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
 				break;
@@ -660,6 +755,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 					 constraint->contype);
 				break;
 		}
+
+		if (saw_default && saw_identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
+							column->colname, cxt->relation->relname),
+					 parser_errposition(cxt->pstate,
+										constraint->location)));
 	}
 
 	/*
@@ -889,6 +992,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		def->storage = 0;
 		def->raw_default = NULL;
 		def->cooked_default = NULL;
+		def->identity = ' ';
 		def->collClause = NULL;
 		def->collOid = attribute->attcollation;
 		def->constraints = NIL;
@@ -904,7 +1008,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		/*
 		 * Copy default, if present and the default has been requested
 		 */
-		if (attribute->atthasdef &&
+		if (attribute->atthasdef && attribute->attidentity == ' ' &&
 			(table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS))
 		{
 			Node	   *this_default = NULL;
@@ -932,6 +1036,29 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			def->cooked_default = this_default;
 		}
 
+		/*
+		 * Copy identity if requested
+		 */
+		if (attribute->attidentity != ' ' &&
+			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
+		{
+			Oid         seq_relid;
+			List	   *seq_options;
+			char	   *snamespace;
+			char	   *sname;
+
+			/*
+			 * find sequence owned by old column; extract sequence parameters;
+			 * build new create sequence command
+			 */
+			seq_relid = getOwnedSequence(RelationGetRelid(relation), attribute->attnum);
+			seq_options = sequence_options(seq_relid);
+			generateSerialExtraStmts(cxt, def,
+									 InvalidOid, seq_options, DEPENDENCY_INTERNAL,
+									 &snamespace, &sname);
+			def->identity = attribute->attidentity;
+		}
+
 		/* Likewise, copy storage if requested */
 		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
 			def->storage = attribute->attstorage;
@@ -1108,6 +1235,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 		n->storage = 0;
 		n->raw_default = NULL;
 		n->cooked_default = NULL;
+		n->identity = ' ';
 		n->collClause = NULL;
 		n->collOid = attr->attcollation;
 		n->constraints = NIL;
@@ -2630,6 +2758,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 			case AT_AlterColumnType:
 				{
 					ColumnDef  *def = (ColumnDef *) cmd->def;
+					AttrNumber	attnum;
 
 					/*
 					 * For ALTER COLUMN TYPE, transform the USING clause if
@@ -2642,6 +2771,110 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 										  EXPR_KIND_ALTER_COL_TRANSFORM);
 					}
 
+					/*
+					 * For identity column, create ALTER SEQUENCE command to
+					 * change the data type of the sequence.
+					 */
+					attnum = get_attnum(relid, cmd->name);
+					/* if attribute not found, something will error about it later */
+					if (attnum != InvalidAttrNumber && get_attidentity(relid, attnum) != ' ')
+					{
+						Oid			seq_relid = getOwnedSequence(relid, attnum);
+						Oid			typeOid = typenameTypeId(pstate, def->typeName);
+						AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
+
+						if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+							ereport(ERROR,
+									(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+									 errmsg("identity column type must be smallint, integer, or bigint")));
+
+						altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															get_rel_name(seq_relid),
+															-1);
+						altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
+						cxt.blist = lappend(cxt.blist, altseqstmt);
+					}
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_AddIdentity:
+				{
+					Constraint  *def = castNode(Constraint, cmd->def);
+					ColumnDef *newdef = makeNode(ColumnDef);
+					Oid			typeOid;
+					char	   *snamespace;
+					char	   *sname;
+
+					typeOid = get_atttype(relid, get_attnum(relid, cmd->name));
+					if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("identity column type must be smallint, integer, or bigint")));
+
+					newdef->colname = cmd->name;
+					newdef->identity = def->generated_when;
+					cmd->def = (Node *) newdef;
+
+					generateSerialExtraStmts(&cxt, newdef,
+											 typeOid, def->options, DEPENDENCY_INTERNAL,
+											 &snamespace, &sname);
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_SetIdentity:
+				{
+					/*
+					 * Create an ALTER SEQUENCE statement for the internal
+					 * sequence of the identity column.
+					 */
+					ListCell   *lc;
+					List	   *newseqopts = NIL;
+					List	   *newdef = NIL;
+					List	   *seqlist;
+					AttrNumber	attnum;
+
+					/*
+					 * Split options into those handled by ALTER SEQUENCE and
+					 * those for ALTER TABLE proper.
+					 */
+					foreach(lc, castNode(List, cmd->def))
+					{
+						DefElem	   *def = castNode(DefElem, lfirst(lc));
+
+						if (strcmp(def->defname, "generated") == 0)
+							newdef = lappend(newdef, def);
+						else
+							newseqopts = lappend(newseqopts, def);
+					}
+
+					attnum = get_attnum(relid, cmd->name);
+
+					if (attnum)
+					{
+						seqlist = getOwnedSequences(relid, attnum);
+						if (seqlist)
+						{
+							AlterSeqStmt *seqstmt;
+							Oid			seq_relid;
+
+							seqstmt = makeNode(AlterSeqStmt);
+							seq_relid = linitial_oid(seqlist);
+							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															 get_rel_name(seq_relid), -1);
+							seqstmt->options = newseqopts;
+							seqstmt->missing_ok = false;
+
+							cxt.alist = lappend(cxt.alist, seqstmt);
+						}
+					}
+					/* If column was not found or did not own sequences, we
+					 * just let the ALTER TABLE command error out. */
+
+					cmd->def = (Node *) newdef;
 					newcmds = lappend(newcmds, cmd);
 					break;
 				}
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 20bbb37484..be3bc32c61 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -21,6 +21,7 @@
 #include "postgres.h"
 
 #include "access/sysattr.h"
+#include "catalog/dependency.h"
 #include "catalog/pg_type.h"
 #include "commands/trigger.h"
 #include "foreign/fdwapi.h"
@@ -61,6 +62,7 @@ static Query *rewriteRuleAction(Query *parsetree,
 static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static List *rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list);
@@ -705,6 +707,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 static List *
 rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list)
@@ -785,6 +788,7 @@ rewriteTargetListIU(List *targetList,
 	for (attrno = 1; attrno <= numattrs; attrno++)
 	{
 		TargetEntry *new_tle = new_tles[attrno - 1];
+		bool	apply_default;
 
 		att_tup = target_relation->rd_att->attrs[attrno - 1];
 
@@ -797,12 +801,51 @@ rewriteTargetListIU(List *targetList,
 		 * it's an INSERT and there's no tlist entry for the column, or the
 		 * tlist entry is a DEFAULT placeholder node.
 		 */
-		if ((new_tle == NULL && commandType == CMD_INSERT) ||
-			(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
+		apply_default = ((new_tle == NULL && commandType == CMD_INSERT) ||
+						 (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
+
+		if (commandType == CMD_INSERT)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+			{
+				if (override != OVERRIDING_SYSTEM_VALUE)
+					ereport(ERROR,
+							(errcode(ERRCODE_GENERATED_ALWAYS),
+							 errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
+							 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+									   NameStr(att_tup->attname)),
+							 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
+			}
+
+			if (att_tup->attidentity == CONSTR_GENERATED_DEFAULT && override == OVERRIDING_USER_VALUE)
+				apply_default = true;
+		}
+
+		if (commandType == CMD_UPDATE)
+		{
+			if (att_tup->attidentity == CONSTR_GENERATED_ALWAYS && !apply_default)
+				ereport(ERROR,
+						(errcode(ERRCODE_GENERATED_ALWAYS),
+						 errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
+						 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+								   NameStr(att_tup->attname))));
+		}
+
+		if (apply_default)
 		{
 			Node	   *new_expr;
 
-			new_expr = build_column_default(target_relation, attrno);
+			if (att_tup->attidentity != ' ')
+			{
+				NextValueExpr *nve = makeNode(NextValueExpr);
+
+				nve->seqid = getOwnedSequence(RelationGetRelid(target_relation), attrno);
+				nve->typeId = att_tup->atttypid;
+
+				new_expr = (Node *) nve;
+			}
+			else
+				new_expr = build_column_default(target_relation, attrno);
 
 			/*
 			 * If there is no default (ie, default is effectively NULL), we
@@ -3228,6 +3271,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				/* Process the main targetlist ... */
 				parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
 													  parsetree->commandType,
+															parsetree->override,
 															rt_entry_relation,
 												   parsetree->resultRelation,
 															&attrnos);
@@ -3240,6 +3284,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->targetList =
 					rewriteTargetListIU(parsetree->targetList,
 										parsetree->commandType,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation, NULL);
 			}
@@ -3250,6 +3295,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->onConflict->onConflictSet =
 					rewriteTargetListIU(parsetree->onConflict->onConflictSet,
 										CMD_UPDATE,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation,
 										NULL);
@@ -3259,7 +3305,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 		{
 			parsetree->targetList =
 				rewriteTargetListIU(parsetree->targetList,
-									parsetree->commandType, rt_entry_relation,
+									parsetree->commandType,
+									parsetree->override,
+									rt_entry_relation,
 									parsetree->resultRelation, NULL);
 			rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
 		}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index b27b77de21..97cbe11332 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5789,6 +5789,14 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (query->targetList)
 		appendStringInfoString(buf, ") ");
 
+	if (query->override)
+	{
+		if (query->override == OVERRIDING_SYSTEM_VALUE)
+			appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
+		else if (query->override == OVERRIDING_USER_VALUE)
+			appendStringInfoString(buf, "OVERRIDING USER VALUE ");
+	}
+
 	if (select_rte)
 	{
 		/* Add the SELECT */
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index 1b04c098d0..187daf2998 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -836,6 +836,27 @@ get_attnum(Oid relid, const char *attname)
 		return InvalidAttrNumber;
 }
 
+char
+get_attidentity(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		char			result;
+
+		result = att_tup->attidentity;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return 0;
+}
+
 /*
  * get_atttype
  *
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 9001e202b0..df51d9ac6c 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -3267,6 +3267,7 @@ RelationBuildLocalRelation(const char *relname,
 	has_not_null = false;
 	for (i = 0; i < natts; i++)
 	{
+		rel->rd_att->attrs[i]->attidentity = tupDesc->attrs[i]->attidentity;
 		rel->rd_att->attrs[i]->attnotnull = tupDesc->attrs[i]->attnotnull;
 		has_not_null |= tupDesc->attrs[i]->attnotnull;
 	}
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index 46aadd76f7..7d09f9f809 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -326,6 +326,7 @@ Section: Class 42 - Syntax Error or Access Rule Violation
 42P21    E    ERRCODE_COLLATION_MISMATCH                                     collation_mismatch
 42P22    E    ERRCODE_INDETERMINATE_COLLATION                                indeterminate_collation
 42809    E    ERRCODE_WRONG_OBJECT_TYPE                                      wrong_object_type
+428C9    E    ERRCODE_GENERATED_ALWAYS                                       generated_always
 
 # Note: for ERRCODE purposes, we divide namable objects into these categories:
 # databases, schemas, prepared statements, cursors, tables, columns,
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 7273ec8fe2..a70922b07a 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -1891,6 +1891,9 @@ dumpTableData_insert(Archive *fout, void *dcontext)
 						appendPQExpBufferStr(insertStmt, ") ");
 					}
 
+					if (tbinfo->needs_override)
+						appendPQExpBufferStr(insertStmt, "OVERRIDING SYSTEM VALUE ");
+
 					appendPQExpBufferStr(insertStmt, "VALUES (");
 				}
 			}
@@ -5376,6 +5379,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_toastreloptions;
 	int			i_reloftype;
 	int			i_relpages;
+	int			i_is_identity_sequence;
 	int			i_changed_acl;
 
 	/* Make sure we are in proper schema */
@@ -5452,6 +5456,7 @@ getTables(Archive *fout, int *numTables)
 						  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 						  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "
 						  "tc.reloptions AS toast_reloptions, "
+						  "c.relkind = '%c' AND EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND objsubid = 0 AND refclassid = 'pg_class'::regclass AND deptype = 'i') AS is_identity_sequence, "
 						  "EXISTS (SELECT 1 FROM pg_attribute at LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
 						  "AND pip.classoid = 'pg_class'::regclass "
@@ -5468,7 +5473,7 @@ getTables(Archive *fout, int *numTables)
 						  "(c.relkind = '%c' AND "
 						  "d.classid = c.tableoid AND d.objid = c.oid AND "
 						  "d.objsubid = 0 AND "
-						  "d.refclassid = c.tableoid AND d.deptype = 'a') "
+						  "d.refclassid = c.tableoid AND d.deptype IN ('a', 'i')) "
 					   "LEFT JOIN pg_class tc ON (c.reltoastrelid = tc.oid) "
 						  "LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
@@ -5481,6 +5486,7 @@ getTables(Archive *fout, int *numTables)
 						  initacl_subquery->data,
 						  initracl_subquery->data,
 						  username_subquery,
+						  RELKIND_SEQUENCE,
 						  attacl_subquery->data,
 						  attracl_subquery->data,
 						  attinitacl_subquery->data,
@@ -5903,6 +5909,7 @@ getTables(Archive *fout, int *numTables)
 	i_checkoption = PQfnumber(res, "checkoption");
 	i_toastreloptions = PQfnumber(res, "toast_reloptions");
 	i_reloftype = PQfnumber(res, "reloftype");
+	i_is_identity_sequence = PQfnumber(res, "is_identity_sequence");
 	i_changed_acl = PQfnumber(res, "changed_acl");
 
 	if (dopt->lockWaitTimeout)
@@ -6003,6 +6010,8 @@ getTables(Archive *fout, int *numTables)
 		tblinfo[i].dummy_view = false;	/* might get set during sort */
 		tblinfo[i].postponed_def = false;		/* might get set during sort */
 
+		tblinfo[i].is_identity_sequence = (strcmp(PQgetvalue(res, i, i_is_identity_sequence), "t") == 0);
+
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
 		 * in schema before we get around to dumping them.
@@ -7565,6 +7574,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	int			i_typstorage;
 	int			i_attnotnull;
 	int			i_atthasdef;
+	int			i_attidentity;
 	int			i_attisdropped;
 	int			i_attlen;
 	int			i_attalign;
@@ -7607,7 +7617,34 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 
 		resetPQExpBuffer(q);
 
-		if (fout->remoteVersion >= 90200)
+		if (fout->remoteVersion >= 100000)
+		{
+			/*
+			 * attidentity is new in version 10.
+			 */
+			appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
+							  "a.attstattarget, a.attstorage, t.typstorage, "
+							  "a.attnotnull, a.atthasdef, a.attisdropped, "
+							  "a.attlen, a.attalign, a.attislocal, "
+				  "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname, "
+						"array_to_string(a.attoptions, ', ') AS attoptions, "
+							  "CASE WHEN a.attcollation <> t.typcollation "
+						   "THEN a.attcollation ELSE 0 END AS attcollation, "
+							  "a.attidentity, "
+							  "pg_catalog.array_to_string(ARRAY("
+							  "SELECT pg_catalog.quote_ident(option_name) || "
+							  "' ' || pg_catalog.quote_literal(option_value) "
+						"FROM pg_catalog.pg_options_to_table(attfdwoptions) "
+							  "ORDER BY option_name"
+							  "), E',\n    ') AS attfdwoptions "
+			 "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
+							  "ON a.atttypid = t.oid "
+							  "WHERE a.attrelid = '%u'::pg_catalog.oid "
+							  "AND a.attnum > 0::pg_catalog.int2 "
+							  "ORDER BY a.attrelid, a.attnum",
+							  tbinfo->dobj.catId.oid);
+		}
+		else if (fout->remoteVersion >= 90200)
 		{
 			/*
 			 * attfdwoptions is new in 9.2.
@@ -7706,6 +7743,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		i_typstorage = PQfnumber(res, "typstorage");
 		i_attnotnull = PQfnumber(res, "attnotnull");
 		i_atthasdef = PQfnumber(res, "atthasdef");
+		i_attidentity = PQfnumber(res, "attidentity");
 		i_attisdropped = PQfnumber(res, "attisdropped");
 		i_attlen = PQfnumber(res, "attlen");
 		i_attalign = PQfnumber(res, "attalign");
@@ -7721,6 +7759,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		tbinfo->attstattarget = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attstorage = (char *) pg_malloc(ntups * sizeof(char));
 		tbinfo->typstorage = (char *) pg_malloc(ntups * sizeof(char));
+		tbinfo->attidentity = (char *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attisdropped = (bool *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attlen = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attalign = (char *) pg_malloc(ntups * sizeof(char));
@@ -7745,6 +7784,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, j, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
+			tbinfo->attidentity[j] = *(PQgetvalue(res, j, i_attidentity));
+			tbinfo->needs_override = tbinfo->needs_override || (tbinfo->attidentity[j] == 'a');
 			tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
 			tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
 			tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
@@ -16019,10 +16060,13 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
-					  fmtId(tbinfo->dobj.namespace->dobj.name));
-	appendPQExpBuffer(delqry, "%s;\n",
-					  fmtId(tbinfo->dobj.name));
+	if (!tbinfo->is_identity_sequence)
+	{
+		appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+		appendPQExpBuffer(delqry, "%s;\n",
+						  fmtId(tbinfo->dobj.name));
+	}
 
 	resetPQExpBuffer(query);
 
@@ -16034,11 +16078,30 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 												tbinfo->dobj.catId.oid);
 	}
 
-	appendPQExpBuffer(query,
-					  "CREATE SEQUENCE %s\n",
-					  fmtId(tbinfo->dobj.name));
+	if (tbinfo->is_identity_sequence)
+	{
+		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+
+		appendPQExpBuffer(query,
+						  "ALTER TABLE %s ",
+						  fmtId(owning_tab->dobj.name));
+		appendPQExpBuffer(query,
+						  "ALTER COLUMN %s ADD GENERATED ",
+						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
+		if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'a')
+			appendPQExpBuffer(query, "ALWAYS");
+		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == 'd')
+			appendPQExpBuffer(query, "BY DEFAULT");
+		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+						  fmtId(tbinfo->dobj.name));
+	}
+	else
+		appendPQExpBuffer(query,
+						  "CREATE SEQUENCE %s\n",
+						  fmtId(tbinfo->dobj.name));
 
-	if (strcmp(seqtype, "bigint") != 0)
+	if (strcmp(seqtype, "bigint") != 0 &&
+		!tbinfo->is_identity_sequence)
 		appendPQExpBuffer(query, "    AS %s\n", seqtype);
 
 	if (fout->remoteVersion >= 80400)
@@ -16060,7 +16123,10 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "    CACHE %s%s",
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
-	appendPQExpBufferStr(query, ";\n");
+	if (tbinfo->is_identity_sequence)
+		appendPQExpBufferStr(query, "\n);\n");
+	else
+		appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
@@ -16093,7 +16159,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	 * We need not schema-qualify the table reference because both sequence
 	 * and table must be in the same schema.
 	 */
-	if (OidIsValid(tbinfo->owning_tab))
+	if (OidIsValid(tbinfo->owning_tab) && !tbinfo->is_identity_sequence)
 	{
 		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
 
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index a466527ec6..f5ea2f7a6f 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -287,6 +287,7 @@ typedef struct _tableInfo
 	/* these two are set only if table is a sequence owned by a column: */
 	Oid			owning_tab;		/* OID of table owning sequence */
 	int			owning_col;		/* attr # of column owning sequence */
+	bool		is_identity_sequence;
 	int			relpages;		/* table's size in pages (from pg_class) */
 
 	bool		interesting;	/* true if need to collect more data */
@@ -305,6 +306,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	char	   *attidentity;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
 	char	   *attalign;		/* attribute align, used by binary_upgrade */
 	bool	   *attislocal;		/* true if attr has local definition */
@@ -316,6 +318,7 @@ typedef struct _tableInfo
 	struct _attrDefInfo **attrdefs;		/* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
 	char	   *partkeydef;		/* partition key definition */
+	bool		needs_override;	/* has GENERATED ALWAYS AS IDENTITY */
 
 	/*
 	 * Stuff computed only for dumpable tables.
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index e2e4cbcc08..920cb98371 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -1582,6 +1582,10 @@ describeOneTableDetails(const char *schemaname,
 							 "   WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation");
 	else
 		appendPQExpBufferStr(&buf, "\n  NULL AS attcollation");
+	if (pset.sversion >= 100000)
+		appendPQExpBufferStr(&buf, ", a.attidentity");
+	else
+		appendPQExpBufferStr(&buf, ", NULL AS attidentity");
 	if (tableinfo.relkind == 'i')
 		appendPQExpBufferStr(&buf, ",\n  pg_catalog.pg_get_indexdef(a.attrelid, a.attnum, TRUE) AS indexdef");
 	else
@@ -1756,12 +1760,24 @@ describeOneTableDetails(const char *schemaname,
 		/* Collation, Nullable, Default */
 		if (show_column_details)
 		{
+			char   *identity;
+			char   *default_str = "";
+
 			printTableAddCell(&cont, PQgetvalue(res, i, 5), false, false);
 
 			printTableAddCell(&cont, strcmp(PQgetvalue(res, i, 3), "t") == 0 ? "not null" : "", false, false);
 
-			/* (note: above we cut off the 'default' string at 128) */
-			printTableAddCell(&cont, PQgetvalue(res, i, 2), false, false);
+			identity = PQgetvalue(res, i, 6);
+
+			if (identity[0] == ' ')
+				/* (note: above we cut off the 'default' string at 128) */
+				default_str = PQgetvalue(res, i, 2);
+			else if (identity[0] == 'a')
+				default_str = "generated always as identity";
+			else if (identity[0] == 'd')
+				default_str = "generated by default as identity";
+
+			printTableAddCell(&cont, default_str, false, false);
 		}
 
 		/* Value: for sequences only */
@@ -1770,16 +1786,16 @@ describeOneTableDetails(const char *schemaname,
 
 		/* Expression for index column */
 		if (tableinfo.relkind == 'i')
-			printTableAddCell(&cont, PQgetvalue(res, i, 6), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
 
 		/* FDW options for foreign table column, only for 9.2 or later */
 		if (tableinfo.relkind == 'f' && pset.sversion >= 90200)
-			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 8), false, false);
 
 		/* Storage and Description */
 		if (verbose)
 		{
-			int			firstvcol = 8;
+			int			firstvcol = 9;
 			char	   *storage = PQgetvalue(res, i, firstvcol);
 
 			/* these strings are literal in our syntax, so not translated. */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index ddad71a10f..ac91cef3d2 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1855,7 +1855,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> */
 	else if (Matches6("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny) ||
 			 Matches5("ALTER", "TABLE", MatchAny, "ALTER", MatchAny))
-		COMPLETE_WITH_LIST4("TYPE", "SET", "RESET", "DROP");
+		COMPLETE_WITH_LIST5("TYPE", "SET", "RESET", "ADD", "DROP");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
@@ -1871,7 +1871,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> DROP */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "DROP") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "DROP"))
-		COMPLETE_WITH_LIST2("DEFAULT", "NOT NULL");
+		COMPLETE_WITH_LIST3("DEFAULT", "IDENTITY", "NOT NULL");
 	else if (Matches4("ALTER", "TABLE", MatchAny, "CLUSTER"))
 		COMPLETE_WITH_CONST("ON");
 	else if (Matches5("ALTER", "TABLE", MatchAny, "CLUSTER", "ON"))
@@ -2870,17 +2870,25 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * Complete INSERT INTO <table> with "(" or "VALUES" or "SELECT" or
-	 * "TABLE" or "DEFAULT VALUES"
+	 * "TABLE" or "DEFAULT VALUES" or "OVERRIDING"
 	 */
 	else if (TailMatches3("INSERT", "INTO", MatchAny))
-		COMPLETE_WITH_LIST5("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES");
+		COMPLETE_WITH_LIST6("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES", "OVERRIDING");
 
 	/*
 	 * Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" or
-	 * "TABLE"
+	 * "TABLE" or "OVERRIDING"
 	 */
 	else if (TailMatches4("INSERT", "INTO", MatchAny, MatchAny) &&
 			 ends_with(prev_wd, ')'))
+		COMPLETE_WITH_LIST4("SELECT", "TABLE", "VALUES", "OVERRIDING");
+
+	/* Complete OVERRIDING */
+	else if (TailMatches1("OVERRIDING"))
+		COMPLETE_WITH_LIST2("SYSTEM VALUE", "USER VALUE");
+
+	/* Complete after OVERRIDING clause */
+	else if (TailMatches3("OVERRIDING", MatchAny, "VALUE"))
 		COMPLETE_WITH_LIST3("SELECT", "TABLE", "VALUES");
 
 	/* Insert an open parenthesis after "VALUES" */
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 9e8c1c2a02..97e4e32987 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201702231
+#define CATALOG_VERSION_NO	201702285
 
 #endif
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 10759c7c58..ae040ca530 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -241,7 +241,8 @@ extern bool sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId);
 
 extern void markSequenceUnowned(Oid seqId);
 
-extern List *getOwnedSequences(Oid relid);
+extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
+extern Oid getOwnedSequence(Oid relid, AttrNumber attnum);
 
 extern Oid	get_constraint_index(Oid constraintId);
 
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index e861f4c589..1e28a626bc 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -133,6 +133,9 @@ CATALOG(pg_attribute,1249) BKI_BOOTSTRAP BKI_WITHOUT_OIDS BKI_ROWTYPE_OID(75) BK
 	/* Has DEFAULT value or not */
 	bool		atthasdef;
 
+	/* 'a', 'd', or ' ' */
+	char		attidentity;
+
 	/* Is dropped (ie, logically invisible) or not */
 	bool		attisdropped;
 
@@ -188,7 +191,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
-#define Natts_pg_attribute				21
+#define Natts_pg_attribute				22
 #define Anum_pg_attribute_attrelid		1
 #define Anum_pg_attribute_attname		2
 #define Anum_pg_attribute_atttypid		3
@@ -203,13 +206,14 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 #define Anum_pg_attribute_attalign		12
 #define Anum_pg_attribute_attnotnull	13
 #define Anum_pg_attribute_atthasdef		14
-#define Anum_pg_attribute_attisdropped	15
-#define Anum_pg_attribute_attislocal	16
-#define Anum_pg_attribute_attinhcount	17
-#define Anum_pg_attribute_attcollation	18
-#define Anum_pg_attribute_attacl		19
-#define Anum_pg_attribute_attoptions	20
-#define Anum_pg_attribute_attfdwoptions 21
+#define Anum_pg_attribute_attidentity	15
+#define Anum_pg_attribute_attisdropped	16
+#define Anum_pg_attribute_attislocal	17
+#define Anum_pg_attribute_attinhcount	18
+#define Anum_pg_attribute_attcollation	19
+#define Anum_pg_attribute_attacl		20
+#define Anum_pg_attribute_attoptions	21
+#define Anum_pg_attribute_attfdwoptions 22
 
 
 /* ----------------
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index 3f96611f74..1734978d61 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -149,7 +149,7 @@ typedef FormData_pg_class *Form_pg_class;
  */
 DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 21 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
 DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 29 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 49a77c42fc..304586e48e 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -51,7 +51,9 @@ typedef struct xl_seq_rec
 	/* SEQUENCE TUPLE DATA FOLLOWS AT THE END */
 } xl_seq_rec;
 
+extern int64 nextval_internal(Oid relid, bool check_permissions);
 extern Datum nextval(PG_FUNCTION_ARGS);
+extern List *sequence_options(Oid relid);
 
 extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
 extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 28aca928a8..feedd0f540 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -183,6 +183,7 @@ typedef enum NodeTag
 	T_FromExpr,
 	T_OnConflictExpr,
 	T_IntoClause,
+	T_NextValueExpr,
 
 	/*
 	 * TAGS FOR EXPRESSION STATE NODES (execnodes.h)
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 5afc3ebea0..280342104a 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -27,6 +27,13 @@
 #include "nodes/primnodes.h"
 #include "nodes/value.h"
 
+typedef enum OverridingKind
+{
+	OVERRIDING_NOT_SET = 0,
+	OVERRIDING_USER_VALUE,
+	OVERRIDING_SYSTEM_VALUE
+} OverridingKind;
+
 /* Possible sources of a Query */
 typedef enum QuerySource
 {
@@ -130,6 +137,8 @@ typedef struct Query
 
 	List	   *targetList;		/* target list (of TargetEntry) */
 
+	OverridingKind override;	/* OVERRIDING clause */
+
 	OnConflictExpr *onConflict; /* ON CONFLICT DO [NOTHING | UPDATE] */
 
 	List	   *returningList;	/* return-values list (of TargetEntry) */
@@ -604,6 +613,7 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	char		identity;		/* attidentity setting */
 	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
@@ -625,9 +635,10 @@ typedef enum TableLikeOption
 {
 	CREATE_TABLE_LIKE_DEFAULTS = 1 << 0,
 	CREATE_TABLE_LIKE_CONSTRAINTS = 1 << 1,
-	CREATE_TABLE_LIKE_INDEXES = 1 << 2,
-	CREATE_TABLE_LIKE_STORAGE = 1 << 3,
-	CREATE_TABLE_LIKE_COMMENTS = 1 << 4,
+	CREATE_TABLE_LIKE_IDENTITY = 1 << 2,
+	CREATE_TABLE_LIKE_INDEXES = 1 << 3,
+	CREATE_TABLE_LIKE_STORAGE = 1 << 4,
+	CREATE_TABLE_LIKE_COMMENTS = 1 << 5,
 	CREATE_TABLE_LIKE_ALL = PG_INT32_MAX
 } TableLikeOption;
 
@@ -1360,6 +1371,7 @@ typedef struct InsertStmt
 	OnConflictClause *onConflictClause; /* ON CONFLICT clause */
 	List	   *returningList;	/* list of expressions to return */
 	WithClause *withClause;		/* WITH clause */
+	OverridingKind override;	/* OVERRIDING clause */
 } InsertStmt;
 
 /* ----------------------
@@ -1669,7 +1681,10 @@ typedef enum AlterTableType
 	AT_NoForceRowSecurity,		/* NO FORCE ROW SECURITY */
 	AT_GenericOptions,			/* OPTIONS (...) */
 	AT_AttachPartition,			/* ATTACH PARTITION */
-	AT_DetachPartition			/* DETACH PARTITION */
+	AT_DetachPartition,			/* DETACH PARTITION */
+	AT_AddIdentity,				/* ADD IDENTITY */
+	AT_SetIdentity,				/* SET identity column options */
+	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
@@ -1942,6 +1957,7 @@ typedef enum ConstrType			/* types of constraints */
 								 * expect it */
 	CONSTR_NOTNULL,
 	CONSTR_DEFAULT,
+	CONSTR_IDENTITY,
 	CONSTR_CHECK,
 	CONSTR_PRIMARY,
 	CONSTR_UNIQUE,
@@ -1953,6 +1969,9 @@ typedef enum ConstrType			/* types of constraints */
 	CONSTR_ATTR_IMMEDIATE
 } ConstrType;
 
+#define CONSTR_GENERATED_ALWAYS		'a'
+#define CONSTR_GENERATED_DEFAULT	'd'
+
 /* Foreign key action codes */
 #define FKCONSTR_ACTION_NOACTION	'a'
 #define FKCONSTR_ACTION_RESTRICT	'r'
@@ -1980,6 +1999,7 @@ typedef struct Constraint
 	bool		is_no_inherit;	/* is constraint non-inheritable? */
 	Node	   *raw_expr;		/* expr, as untransformed parse tree */
 	char	   *cooked_expr;	/* expr, as nodeToString representation */
+	char		generated_when;
 
 	/* Fields used for unique constraints (UNIQUE and PRIMARY KEY): */
 	List	   *keys;			/* String nodes naming referenced column(s) */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index 235bc75096..ff50bc87a7 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1270,6 +1270,20 @@ typedef struct InferenceElem
 	Oid			inferopclass;	/* OID of att opclass, or InvalidOid */
 } InferenceElem;
 
+/*
+ * NextValueExpr - get next value from sequence
+ *
+ * This has the same effect as calling the nextval() function, but it does not
+ * check permissions on the sequence.  This is used for identity columns,
+ * where the sequence is an implicit dependency without its own permissions.
+ */
+typedef struct NextValueExpr
+{
+	Expr		xpr;
+	Oid			seqid;
+	Oid			typeId;
+} NextValueExpr;
+
 /*--------------------
  * TargetEntry -
  *	   a target entry (used in query target lists)
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 985d6505ec..e1a0a53e16 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -173,6 +173,7 @@ PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
 PG_KEYWORD("full", FULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("function", FUNCTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("functions", FUNCTIONS, UNRESERVED_KEYWORD)
+PG_KEYWORD("generated", GENERATED, UNRESERVED_KEYWORD)
 PG_KEYWORD("global", GLOBAL, UNRESERVED_KEYWORD)
 PG_KEYWORD("grant", GRANT, RESERVED_KEYWORD)
 PG_KEYWORD("granted", GRANTED, UNRESERVED_KEYWORD)
@@ -285,6 +286,7 @@ PG_KEYWORD("outer", OUTER_P, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("over", OVER, UNRESERVED_KEYWORD)
 PG_KEYWORD("overlaps", OVERLAPS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("overlay", OVERLAY, COL_NAME_KEYWORD)
+PG_KEYWORD("overriding", OVERRIDING, UNRESERVED_KEYWORD)
 PG_KEYWORD("owned", OWNED, UNRESERVED_KEYWORD)
 PG_KEYWORD("owner", OWNER, UNRESERVED_KEYWORD)
 PG_KEYWORD("parallel", PARALLEL, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index b6d1fca2fa..88629d99aa 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -64,6 +64,7 @@ extern Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 extern char *get_attname(Oid relid, AttrNumber attnum);
 extern char *get_relid_attribute_name(Oid relid, AttrNumber attnum);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
+extern char	get_attidentity(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index a25b221703..3f405c94ce 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -66,6 +66,53 @@ SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y
 (2 rows)
 
 DROP TABLE inhg;
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+                     Table "public.test_like_id_1"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+ a | b  
+---+----
+ 1 | b1
+(1 row)
+
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+           Table "public.test_like_id_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           | not null | 
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, b2).
+SELECT * FROM test_like_id_2;  -- identity was not copied
+ a | b 
+---+---
+(0 rows)
+
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+                     Table "public.test_like_id_3"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+ a | b  
+---+----
+ 1 | b3
+(1 row)
+
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
new file mode 100644
index 0000000000..bf6158b315
--- /dev/null
+++ b/src/test/regress/expected/identity.out
@@ -0,0 +1,306 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest3" is already an identity column
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+ table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
+------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
+ itest1     | a           |                | NO          | YES         | BY DEFAULT          | 1              | 1                  | 2147483647          | 1                | NO
+ itest1     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest2     | a           |                | NO          | YES         | ALWAYS              | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest2     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest3     | a           |                | NO          | YES         | BY DEFAULT          | 7              | 5                  | 32767               | 1                | NO
+ itest3     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+(6 rows)
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+ sequence_name 
+---------------
+(0 rows)
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ERROR:  column "a" of relation "itest4" is an identity column
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ERROR:  column "a" of relation "itest4" is already an identity column
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ERROR:  identity column type must be smallint, integer, or bigint
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+ERROR:  identity column type must be smallint, integer, or bigint
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+ERROR:  multiple identity specifications for column "a" of table "itest_err_2"
+LINE 1: ...E itest_err_2 (a int generated always as identity generated ...
+                                                             ^
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_3"
+LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau...
+                                                  ^
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_4"
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest1;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest2;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest3;
+ a  | b 
+----+---
+  7 | 
+ 12 | 
+(2 rows)
+
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+-- OVERRIDING tests
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+SELECT * FROM itest1;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+(3 rows)
+
+-- UPDATE tests
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+  a  |  b  
+-----+-----
+  10 | xyz
+   3 | xyz
+ 101 | 
+   4 | 
+(4 rows)
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+ERROR:  column "a" can only be updated to DEFAULT
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+ 10 | xyz
+  3 | 
+(3 rows)
+
+-- DROP IDENTITY tests
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is not an identity column
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, ).
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+   | 
+(3 rows)
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+ERROR:  relation "itest4_a_seq" does not exist
+LINE 1: SELECT sequence_name FROM itest4_a_seq;
+                                  ^
+-- test views
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+SELECT * FROM itestv10;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itestv11;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv10;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv11;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 11 | xyz
+(3 rows)
+
+-- various ALTER COLUMN tests
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+ERROR:  column "a" of relation "itest1" is an identity column
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ERROR:  column "a" of relation "itest5" already has a default value
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+ seqtypid 
+----------
+ integer
+(1 row)
+
+\d itest3
+                           Table "public.itest3"
+ Column |  Type   | Collation | Nullable |             Default              
+--------+---------+-----------+----------+----------------------------------
+ a      | integer |           | not null | generated by default as identity
+ b      | text    |           |          | 
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+ERROR:  identity column type must be smallint, integer, or bigint
+-- ALTER COLUMN ... SET
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+  a  | b 
+-----+---
+   1 | 
+ 100 | 
+ 102 | 
+(3 rows)
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+ table_name | column_name | is_identity | identity_generation 
+------------+-------------+-------------+---------------------
+ itest6     | a           | YES         | BY DEFAULT
+ itest6     | b           | NO          | 
+(2 rows)
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+ERROR:  column "b" of relation "itest6" is not an identity column
+-- inheritance
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+(1 row)
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+NOTICE:  merging column "a" with inherited definition
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+ a 
+---
+ 1
+(1 row)
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  cannot recursively add identity column to table that has child tables
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+ table_name | column_name | is_nullable | is_identity | identity_generation 
+------------+-------------+-------------+-------------+---------------------
+ itest7     | a           | NO          | YES         | ALWAYS
+ itest7a    | a           | NO          | NO          | 
+ itest7a    | b           | YES         | NO          | 
+ itest7b    | a           | YES         | NO          | 
+ itest7c    | a           | NO          | YES         | ALWAYS
+ itest7d    | a           | NO          | YES         | ALWAYS
+ itest7e    | a           | NO          | YES         | ALWAYS
+(7 rows)
+
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+ a | b 
+---+---
+ 1 | 
+(1 row)
+
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/expected/sequence.out b/src/test/regress/expected/sequence.out
index f339489151..469c082ad1 100644
--- a/src/test/regress/expected/sequence.out
+++ b/src/test/regress/expected/sequence.out
@@ -20,8 +20,8 @@ ERROR:  CACHE (0) must be greater than zero
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
 ERROR:  invalid OWNED BY option
 HINT:  Specify OWNED BY table.column or OWNED BY NONE.
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
-ERROR:  referenced relation "pg_tables" is not a table or foreign table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
+ERROR:  referenced relation "pg_class_oid_index" is not a table or foreign table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 ERROR:  sequence must be in same schema as table it is linked to
 CREATE TABLE sequence_test_table (a int);
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index 5c5277e0f1..c76a21788f 100644
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -393,6 +393,36 @@ SELECT * FROM truncate_a;
   2 |  34
 (2 rows)
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
+TRUNCATE truncate_b;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 46
+ 47
+(2 rows)
+
+TRUNCATE truncate_b RESTART IDENTITY;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index edeb2d6bc7..74d1805708 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -111,6 +111,11 @@ test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combo
 # ----------
 test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml
 
+# ----------
+# Another group of parallel tests
+# ----------
+test: identity
+
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger
 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 27a46d76d5..342e03f6e9 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -164,6 +164,7 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
+test: identity
 test: polymorphism
 test: rowtypes
 test: returning
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 900ca804cb..557040bbe7 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -37,6 +37,20 @@ CREATE TABLE inhg (x text, LIKE inhx INCLUDING CONSTRAINTS, y text); /* Copies c
 SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y */
 DROP TABLE inhg;
 
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+SELECT * FROM test_like_id_2;  -- identity was not copied
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
+
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
new file mode 100644
index 0000000000..775e8ef285
--- /dev/null
+++ b/src/test/regress/sql/identity.sql
@@ -0,0 +1,177 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+
+SELECT * FROM itest1;
+SELECT * FROM itest2;
+SELECT * FROM itest3;
+SELECT * FROM itest4;
+
+
+-- OVERRIDING tests
+
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest1;
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest2;
+
+
+-- UPDATE tests
+
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+
+
+-- DROP IDENTITY tests
+
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+
+
+-- test views
+
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+
+SELECT * FROM itestv10;
+SELECT * FROM itestv11;
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv10;
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv11;
+
+
+-- various ALTER COLUMN tests
+
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+\d itest3
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+
+
+-- ALTER COLUMN ... SET
+
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+
+
+-- inheritance
+
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
index 0fbd255967..18fa6ae5e9 100644
--- a/src/test/regress/sql/sequence.sql
+++ b/src/test/regress/sql/sequence.sql
@@ -13,7 +13,7 @@ CREATE SEQUENCE sequence_testx CACHE 0;
 
 -- OWNED BY errors
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 CREATE TABLE sequence_test_table (a int);
 CREATE SEQUENCE sequence_testx OWNED BY sequence_test_table.b;  -- wrong column
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index a3d6f5368f..1aab021dbb 100644
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -202,6 +202,24 @@ CREATE TABLE truncate_a (id serial,
 INSERT INTO truncate_a DEFAULT VALUES;
 SELECT * FROM truncate_a;
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b RESTART IDENTITY;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
-- 
2.12.0

From 3f65ff393ff6a8171600eb0ae3b3442bbbbda1e8 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 28 Feb 2017 21:09:02 -0500
Subject: [PATCH v5] Identity columns

This is the SQL standard-conforming variant of PostgreSQL's serial
columns.  It also fixes a few usability issues that serial columns
have:

- CREATE TABLE / LIKE copies default but refers to same sequence
- cannot add/drop serialness with ALTER TABLE
- dropping default does not drop sequence
- need to grant separate privileges to sequence
- slight weirdnesses because serial is some kind of special macro
---
 doc/src/sgml/catalogs.sgml                      |  11 +
 doc/src/sgml/information_schema.sgml            |  11 +-
 doc/src/sgml/ref/alter_table.sgml               |  36 ++-
 doc/src/sgml/ref/copy.sgml                      |   7 +
 doc/src/sgml/ref/create_table.sgml              |  65 +++-
 doc/src/sgml/ref/insert.sgml                    |  41 +++
 src/backend/access/common/tupdesc.c             |   5 +
 src/backend/catalog/dependency.c                |   7 +
 src/backend/catalog/genbki.pl                   |   2 +
 src/backend/catalog/heap.c                      |  15 +-
 src/backend/catalog/index.c                     |   1 +
 src/backend/catalog/information_schema.sql      |  17 +-
 src/backend/catalog/pg_depend.c                 |  52 ++--
 src/backend/catalog/sql_features.txt            |  12 +-
 src/backend/commands/sequence.c                 | 109 +++++--
 src/backend/commands/tablecmds.c                | 284 +++++++++++++++++-
 src/backend/executor/execQual.c                 |  21 ++
 src/backend/nodes/copyfuncs.c                   |  21 ++
 src/backend/nodes/equalfuncs.c                  |  16 +
 src/backend/nodes/makefuncs.c                   |   2 +
 src/backend/nodes/nodeFuncs.c                   |  11 +
 src/backend/nodes/outfuncs.c                    |   9 +
 src/backend/nodes/readfuncs.c                   |   1 +
 src/backend/parser/analyze.c                    |   2 +
 src/backend/parser/gram.y                       | 128 +++++++-
 src/backend/parser/parse_utilcmd.c              | 379 +++++++++++++++++++-----
 src/backend/rewrite/rewriteHandler.c            |  56 +++-
 src/backend/utils/adt/ruleutils.c               |   8 +
 src/backend/utils/cache/lsyscache.c             |  21 ++
 src/backend/utils/cache/relcache.c              |   1 +
 src/backend/utils/errcodes.txt                  |   1 +
 src/bin/pg_dump/pg_dump.c                       |  91 +++++-
 src/bin/pg_dump/pg_dump.h                       |   3 +
 src/bin/psql/describe.c                         |  27 +-
 src/bin/psql/tab-complete.c                     |  18 +-
 src/include/catalog/dependency.h                |   8 +-
 src/include/catalog/pg_attribute.h              |  25 +-
 src/include/catalog/pg_class.h                  |   2 +-
 src/include/commands/sequence.h                 |   2 +
 src/include/nodes/nodes.h                       |   1 +
 src/include/nodes/parsenodes.h                  |  25 +-
 src/include/nodes/primnodes.h                   |  14 +
 src/include/parser/kwlist.h                     |   2 +
 src/include/utils/lsyscache.h                   |   1 +
 src/test/regress/expected/create_table_like.out |  47 +++
 src/test/regress/expected/identity.out          | 314 ++++++++++++++++++++
 src/test/regress/expected/sequence.out          |   4 +-
 src/test/regress/expected/truncate.out          |  30 ++
 src/test/regress/parallel_schedule              |   5 +
 src/test/regress/serial_schedule                |   1 +
 src/test/regress/sql/create_table_like.sql      |  14 +
 src/test/regress/sql/identity.sql               | 187 ++++++++++++
 src/test/regress/sql/sequence.sql               |   2 +-
 src/test/regress/sql/truncate.sql               |  18 ++
 54 files changed, 1996 insertions(+), 197 deletions(-)
 create mode 100644 src/test/regress/expected/identity.out
 create mode 100644 src/test/regress/sql/identity.sql

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index df0435c3f0..394b9e123a 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1120,6 +1120,17 @@ <title><structname>pg_attribute</> Columns</title>
      </row>
 
      <row>
+      <entry><structfield>attidentity</structfield></entry>
+      <entry><type>char</type></entry>
+      <entry></entry>
+      <entry>
+       If a space character, then not an identity column.  Otherwise,
+       <literal>a</literal> = generated always, <literal>d</literal> =
+       generated by default.
+      </entry>
+     </row>
+
+     <row>
       <entry><structfield>attisdropped</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index a3a19ce8ce..02f7927436 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -1583,13 +1583,20 @@ <title><literal>columns</literal> Columns</title>
      <row>
       <entry><literal>is_identity</literal></entry>
       <entry><type>yes_or_no</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>YES</literal>,
+       else <literal>NO</literal>.
+      </entry>
      </row>
 
      <row>
       <entry><literal>identity_generation</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>ALWAYS</literal>
+       or <literal>BY DEFAULT</literal>, reflecting the definition of the
+       column.
+      </entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 077c00373d..458ac9f9e7 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -46,6 +46,9 @@
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESTART [ [ WITH ] <replaceable class="parameter">restart</replaceable> ] } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
@@ -180,6 +183,32 @@ <title>Description</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
+    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
+    <term><literal>DROP IDENTITY</literal></term>
+    <listitem>
+     <para>
+      These forms change whether a column is an identity column or change the
+      generation attribute of an existing identity column.
+      See <xref linkend="sql-createtable"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET <replaceable>sequence_option</replaceable></literal></term>
+    <term><literal>RESTART</literal></term>
+    <listitem>
+     <para>
+      These forms alter the sequence that underlies an existing identity
+      column.  <replaceable>sequence_option</replaceable> is an option
+      supported by <xref linkend="sql-altersequence"> such
+      as <literal>INCREMENT BY</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>SET STATISTICS</literal></term>
     <listitem>
      <para>
@@ -1152,8 +1181,11 @@ <title>Notes</title>
    </para>
 
    <para>
-    The <literal>TRIGGER</>, <literal>CLUSTER</>, <literal>OWNER</>,
-    and <literal>TABLESPACE</> actions never recurse to descendant tables;
+    The actions for identity columns (<literal>ADD
+    GENERATED</literal>, <literal>SET</literal> etc., <literal>DROP
+    IDENTITY</literal>), as well as the actions
+    <literal>TRIGGER</>, <literal>CLUSTER</>, <literal>OWNER</>,
+    and <literal>TABLESPACE</> never recurse to descendant tables;
     that is, they always act as though <literal>ONLY</> were specified.
     Adding a constraint recurses only for <literal>CHECK</> constraints
     that are not marked <literal>NO INHERIT</>.
diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index 7ff62f2a82..215efcd69d 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -480,6 +480,13 @@ <title>Notes</title>
    </para>
 
    <para>
+    For identity columns, the <command>COPY FROM</command> command will always
+    write the column values provided in the input data, like
+    the <command>INPUT</command> option <literal>OVERRIDING SYSTEM
+    VALUE</literal>.
+   </para>
+
+   <para>
     <command>COPY</command> input and output is affected by
     <varname>DateStyle</varname>. To ensure portability to other
     <productname>PostgreSQL</productname> installations that might use
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index bb081ff86f..d808ad4d64 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -62,6 +62,7 @@
   NULL |
   CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
   REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
@@ -81,7 +82,7 @@
 
 <phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
 
-{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
+{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | IDENTITY | INDEXES | STORAGE | COMMENTS | ALL }
 
 <phrase>and <replaceable class="PARAMETER">partition_bound_spec</replaceable> is:</phrase>
 
@@ -412,6 +413,11 @@ <title>Parameters</title>
       Column <literal>STORAGE</> settings are also copied from parent tables.
      </para>
 
+     <para>
+      If a column in the parent table is an identity column, that property is
+      not inherited.  A column in the child table can be declared identity
+      column if desired.
+     </para>
     </listitem>
    </varlistentry>
 
@@ -481,6 +487,12 @@ <title>Parameters</title>
       the original and new tables.
      </para>
      <para>
+      Any identity specifications of copied column definitions will only be
+      copied if <literal>INCLUDING IDENTITY</literal> is specified.  A new
+      sequence is created for each identity column of the new table, separate
+      from the sequences associated with the old table.
+     </para>
+     <para>
       Not-null constraints are always copied to the new table.
       <literal>CHECK</literal> constraints will be copied only if
       <literal>INCLUDING CONSTRAINTS</literal> is specified.
@@ -512,7 +524,7 @@ <title>Parameters</title>
      </para>
      <para>
       <literal>INCLUDING ALL</literal> is an abbreviated form of
-      <literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
+      <literal>INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
      </para>
      <para>
       Note that unlike <literal>INHERITS</literal>, columns and
@@ -627,6 +639,37 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]</literal></term>
+    <listitem>
+     <para>
+      This clause creates the column as an <firstterm>identity
+      column</firstterm>.  It will have an implicit sequence attached to it
+      and the column in new rows will automatically have values from the
+      sequence assigned to it.
+     </para>
+
+     <para>
+      The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
+      determine how the sequence value is given precedence over a
+      user-specified value in an <command>INSERT</command> statement.
+      If <literal>ALWAYS</literal> is specified, a user-specified value is
+      only accepted if the <command>INSERT</command> statement
+      specifies <literal>OVERRIDING SYSTEM VALUE</literal>.  If <literal>BY
+      DEFAULT</literal> is specified, then the user-specified value takes
+      precedence.  See <xref linkend="sql-insert"> for details.  (In
+      the <command>COPY</command> command, user-specified values are always
+      used regardless of this setting.)
+     </para>
+
+     <para>
+      The optional <replaceable>sequence_options</replaceable> clause can be
+      used to override the options of the sequence.
+      See <xref linkend="sql-createsequence"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>UNIQUE</> (column constraint)</term>
     <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
 
@@ -1259,7 +1302,7 @@ <title>Notes</title>
 
     <para>
      Using OIDs in new applications is not recommended: where
-     possible, using a <literal>SERIAL</literal> or other sequence
+     possible, using an identity column or other sequence
      generator as the table's primary key is preferred. However, if
      your application does make use of OIDs to identify specific
      rows of a table, it is recommended to create a unique constraint
@@ -1319,7 +1362,7 @@ <title>Examples</title>
 );
 
 CREATE TABLE distributors (
-     did    integer PRIMARY KEY DEFAULT nextval('serial'),
+     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
      name   varchar(40) NOT NULL CHECK (name &lt;&gt; '')
 );
 </programlisting>
@@ -1734,6 +1777,20 @@ <title>Zero-column Tables</title>
   </refsect2>
 
   <refsect2>
+   <title>Multiple Identity Columns</title>
+
+   <para>
+    <productname>PostgreSQL</productname> allows a table to have more than one
+    identity column.  The standard specifies that a table can have at most one
+    identity column.  This is relaxed mainly to give more flexibility for
+    doing schema changes or migrations.  Note that
+    the <command>INSERT</command> command supports only one override clause
+    that applies to the entire statement, so having multiple identity columns
+    with different behaviors is not well supported.
+   </para>
+  </refsect2>
+
+  <refsect2>
    <title><literal>LIKE</> Clause</title>
 
    <para>
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 521216b5d5..95aa77b907 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -23,6 +23,7 @@
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
 INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replaceable class="parameter">alias</replaceable> ] [ ( <replaceable class="PARAMETER">column_name</replaceable> [, ...] ) ]
+    [ OVERRIDING { SYSTEM | USER} VALUE ]
     { DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
     [ ON CONFLICT [ <replaceable class="parameter">conflict_target</replaceable> ] <replaceable class="parameter">conflict_action</replaceable> ]
     [ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@@ -202,10 +203,43 @@ <title id="sql-inserting-params-title">Inserting</title>
      </varlistentry>
 
      <varlistentry>
+      <term><literal>OVERRIDING SYSTEM VALUE</literal></term>
+      <listitem>
+       <para>
+        Without this clause, it is an error to specify an explicit value
+        (other than <literal>DEFAULT</literal>) for an identity column defined
+        as <literal>GENERATED ALWAYS</literal>.  This clause overrides that
+        restriction.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>OVERRIDING USER VALUE</literal></term>
+      <listitem>
+       <para>
+        If this clause is specified, then any values supplied for identity
+        columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
+        and the default sequence-generated values are applied.
+       </para>
+
+       <para>
+        This clause is useful for example when copying values between tables.
+        Writing <literal>INSERT INTO tbl2 OVERRIDING USER VALUE SELECT * FROM
+        tbl1</literal> will copy from <literal>tbl1</literal> all columns that
+        are not identity columns in <literal>tbl2</literal> but will continue
+        the sequence counters for any identity columns.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>DEFAULT VALUES</literal></term>
       <listitem>
        <para>
         All columns will be filled with their default values.
+        (An <literal>OVERRIDING</literal> clause is not permitted in this
+        form.)
        </para>
       </listitem>
      </varlistentry>
@@ -711,6 +745,13 @@ <title>Compatibility</title>
   </para>
 
   <para>
+   The SQL standard specifies that <literal>OVERRIDING SYSTEM VALUE</literal>
+   can only be specified if an identity column that is generated always
+   exists.  PostgreSQL allows the clause in any case and ignores it if it is
+   not applicable.
+  </para>
+
+  <para>
    Possible limitations of the <replaceable
    class="PARAMETER">query</replaceable> clause are documented under
    <xref linkend="sql-select">.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 4e2ebe1ae7..f0ecf48b22 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -150,6 +150,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 		desc->attrs[i]->attnotnull = false;
 		desc->attrs[i]->atthasdef = false;
+		desc->attrs[i]->attidentity = ATTRIBUTE_IDENTITY_NONE;
 	}
 
 	desc->tdtypeid = tupdesc->tdtypeid;
@@ -257,6 +258,7 @@ TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 	/* since we're not copying constraints or defaults, clear these */
 	dst->attrs[dstAttno - 1]->attnotnull = false;
 	dst->attrs[dstAttno - 1]->atthasdef = false;
+	dst->attrs[dstAttno - 1]->attidentity = ATTRIBUTE_IDENTITY_NONE;
 }
 
 /*
@@ -401,6 +403,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atthasdef != attr2->atthasdef)
 			return false;
+		if (attr1->attidentity != attr2->attidentity)
+			return false;
 		if (attr1->attisdropped != attr2->attisdropped)
 			return false;
 		if (attr1->attislocal != attr2->attislocal)
@@ -534,6 +538,7 @@ TupleDescInitEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = ATTRIBUTE_IDENTITY_NONE;
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index fc088b2165..76e3c43ba6 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -1923,6 +1923,13 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* fall through to examine arguments */
 	}
+	else if (IsA(node, NextValueExpr))
+	{
+		NextValueExpr  *nve = (NextValueExpr *) node;
+
+		add_object_address(OCLASS_CLASS, nve->seqid, 0,
+						   context->addrs);
+	}
 
 	return expression_tree_walker(node, find_expr_references_walker,
 								  (void *) context);
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index 079516ca2f..93c1274b7f 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -409,6 +409,7 @@ sub emit_pgattr_row
 		attcacheoff   => '-1',
 		atttypmod     => '-1',
 		atthasdef     => 'f',
+		attidentity   => "' '",
 		attisdropped  => 'f',
 		attislocal    => 't',
 		attinhcount   => '0',
@@ -425,6 +426,7 @@ sub bki_insert
 	my @attnames   = @_;
 	my $oid        = $row->{oid} ? "OID = $row->{oid} " : '';
 	my $bki_values = join ' ', map $row->{$_}, @attnames;
+	$bki_values =~ s/'/"/g;
 	printf BKI "insert %s( %s)\n", $oid, $bki_values;
 }
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 41c0056556..c0479510c9 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -142,37 +142,37 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
 static FormData_pg_attribute a1 = {
 	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
 	SelfItemPointerAttributeNumber, 0, -1, -1,
-	false, 'p', 's', true, false, false, true, 0
+	false, 'p', 's', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static FormData_pg_attribute a2 = {
 	0, {"oid"}, OIDOID, 0, sizeof(Oid),
 	ObjectIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static FormData_pg_attribute a3 = {
 	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
 	MinTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static FormData_pg_attribute a4 = {
 	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
 	MinCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static FormData_pg_attribute a5 = {
 	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
 	MaxTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static FormData_pg_attribute a6 = {
 	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
 	MaxCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 /*
@@ -184,7 +184,7 @@ static FormData_pg_attribute a6 = {
 static FormData_pg_attribute a7 = {
 	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
 	TableOidAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, ATTRIBUTE_IDENTITY_NONE, false, true, 0
 };
 
 static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
@@ -618,6 +618,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
 	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
 	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
+	values[Anum_pg_attribute_attidentity - 1] = CharGetDatum(new_attribute->attidentity);
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 8d42a347ea..941303fddd 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -353,6 +353,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->attnotnull = false;
 			to->atthasdef = false;
+			to->attidentity = ATTRIBUTE_IDENTITY_NONE;
 			to->attislocal = true;
 			to->attinhcount = 0;
 			to->attcollation = collationObjectId[i];
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index fa2a88fc5c..2185734b48 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -728,13 +728,13 @@ CREATE VIEW columns AS
            CAST(a.attnum AS sql_identifier) AS dtd_identifier,
            CAST('NO' AS yes_or_no) AS is_self_referencing,
 
-           CAST('NO' AS yes_or_no) AS is_identity,
-           CAST(null AS character_data) AS identity_generation,
-           CAST(null AS character_data) AS identity_start,
-           CAST(null AS character_data) AS identity_increment,
-           CAST(null AS character_data) AS identity_maximum,
-           CAST(null AS character_data) AS identity_minimum,
-           CAST(null AS yes_or_no) AS identity_cycle,
+           CAST(CASE WHEN a.attidentity IN ('a', 'd') THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_identity,
+           CAST(CASE a.attidentity WHEN 'a' THEN 'ALWAYS' WHEN 'd' THEN 'BY DEFAULT' END AS character_data) AS identity_generation,
+           CAST(seq.seqstart AS character_data) AS identity_start,
+           CAST(seq.seqincrement AS character_data) AS identity_increment,
+           CAST(seq.seqmax AS character_data) AS identity_maximum,
+           CAST(seq.seqmin AS character_data) AS identity_minimum,
+           CAST(CASE WHEN seq.seqcycle THEN 'YES' ELSE 'NO' END AS yes_or_no) AS identity_cycle,
 
            CAST('NEVER' AS character_data) AS is_generated,
            CAST(null AS character_data) AS generation_expression,
@@ -751,6 +751,8 @@ CREATE VIEW columns AS
            ON (t.typtype = 'd' AND t.typbasetype = bt.oid)
          LEFT JOIN (pg_collation co JOIN pg_namespace nco ON (co.collnamespace = nco.oid))
            ON a.attcollation = co.oid AND (nco.nspname, co.collname) <> ('pg_catalog', 'default')
+         LEFT JOIN (pg_depend dep JOIN pg_sequence seq ON (dep.classid = 'pg_class'::regclass AND dep.objid = seq.seqrelid AND dep.deptype = 'i'))
+           ON (dep.refclassid = 'pg_class'::regclass AND dep.refobjid = c.oid AND dep.refobjsubid = a.attnum)
 
     WHERE (NOT pg_is_other_temp_schema(nc.oid))
 
@@ -1545,6 +1547,7 @@ CREATE VIEW sequences AS
     FROM pg_namespace nc, pg_class c, pg_sequence s
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
+          AND NOT EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND deptype = 'i')
           AND (NOT pg_is_other_temp_schema(nc.oid))
           AND c.oid = s.seqrelid
           AND (pg_has_role(c.relowner, 'USAGE')
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index d0ee851215..aae879e355 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -488,7 +488,7 @@ getExtensionOfObject(Oid classId, Oid objectId)
 /*
  * Detect whether a sequence is marked as "owned" by a column
  *
- * An ownership marker is an AUTO dependency from the sequence to the
+ * An ownership marker is an AUTO or INTERNAL dependency from the sequence to the
  * column.  If we find one, store the identity of the owning column
  * into *tableId and *colId and return TRUE; else return FALSE.
  *
@@ -497,7 +497,7 @@ getExtensionOfObject(Oid classId, Oid objectId)
  * not happen, though.
  */
 bool
-sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
+sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId)
 {
 	bool		ret = false;
 	Relation	depRel;
@@ -524,7 +524,7 @@ sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
 		Form_pg_depend depform = (Form_pg_depend) GETSTRUCT(tup);
 
 		if (depform->refclassid == RelationRelationId &&
-			depform->deptype == DEPENDENCY_AUTO)
+			depform->deptype == deptype)
 		{
 			*tableId = depform->refobjid;
 			*colId = depform->refobjsubid;
@@ -541,27 +541,15 @@ sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
 }
 
 /*
- * Remove any existing "owned" markers for the specified sequence.
- *
- * Note: we don't provide a special function to install an "owned"
- * marker; just use recordDependencyOn().
- */
-void
-markSequenceUnowned(Oid seqId)
-{
-	deleteDependencyRecordsForClass(RelationRelationId, seqId,
-									RelationRelationId, DEPENDENCY_AUTO);
-}
-
-/*
- * Collect a list of OIDs of all sequences owned by the specified relation.
+ * Collect a list of OIDs of all sequences owned by the specified relation,
+ * and column if specified.
  */
 List *
-getOwnedSequences(Oid relid)
+getOwnedSequences(Oid relid, AttrNumber attnum)
 {
 	List	   *result = NIL;
 	Relation	depRel;
-	ScanKeyData key[2];
+	ScanKeyData key[3];
 	SysScanDesc scan;
 	HeapTuple	tup;
 
@@ -575,23 +563,28 @@ getOwnedSequences(Oid relid)
 				Anum_pg_depend_refobjid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(relid));
+	if (attnum)
+		ScanKeyInit(&key[2],
+					Anum_pg_depend_refobjsubid,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(attnum));
 
 	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 2, key);
+							  NULL, attnum ? 3 : 2, key);
 
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
 		Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
 
 		/*
-		 * We assume any auto dependency of a sequence on a column must be
+		 * We assume any auto or internal dependency of a sequence on a column must be
 		 * what we are looking for.  (We need the relkind test because indexes
 		 * can also have auto dependencies on columns.)
 		 */
 		if (deprec->classid == RelationRelationId &&
 			deprec->objsubid == 0 &&
 			deprec->refobjsubid != 0 &&
-			deprec->deptype == DEPENDENCY_AUTO &&
+			(deprec->deptype == DEPENDENCY_AUTO || deprec->deptype == DEPENDENCY_INTERNAL) &&
 			get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
 		{
 			result = lappend_oid(result, deprec->objid);
@@ -605,6 +598,21 @@ getOwnedSequences(Oid relid)
 	return result;
 }
 
+/*
+ * Get owned sequence, error if not exactly one.
+ */
+Oid
+getOwnedSequence(Oid relid, AttrNumber attnum)
+{
+	List	   *seqlist = getOwnedSequences(relid, attnum);
+
+	if (list_length(seqlist) > 1)
+		elog(ERROR, "more than one owned sequence found");
+	else if (list_length(seqlist) < 1)
+		elog(ERROR, "no owned sequence found");
+	else
+		return linitial_oid(seqlist);
+}
 
 /*
  * get_constraint_index
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 8956ba9304..2821b9b702 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -200,7 +200,7 @@ F181	Multiple module support			NO
 F191	Referential delete actions			YES	
 F200	TRUNCATE TABLE statement			YES	
 F201	CAST function			YES	
-F202	TRUNCATE TABLE: identity column restart option			NO	
+F202	TRUNCATE TABLE: identity column restart option			YES	
 F221	Explicit defaults			YES	
 F222	INSERT statement: DEFAULT VALUES clause			YES	
 F231	Privilege tables			YES	
@@ -241,9 +241,9 @@ F381	Extended schema manipulation	02	ALTER TABLE statement: ADD CONSTRAINT claus
 F381	Extended schema manipulation	03	ALTER TABLE statement: DROP CONSTRAINT clause	YES	
 F382	Alter column data type			YES	
 F383	Set column not null clause			YES	
-F384	Drop identity property clause			NO	
+F384	Drop identity property clause			YES	
 F385	Drop column generation expression clause			NO	
-F386	Set identity column generation clause			NO	
+F386	Set identity column generation clause			YES	
 F391	Long identifiers			YES	
 F392	Unicode escapes in identifiers			YES	
 F393	Unicode escapes in literals			YES	
@@ -420,11 +420,11 @@ T152	DISTINCT predicate with negation			YES
 T171	LIKE clause in table definition			YES	
 T172	AS subquery clause in table definition			YES	
 T173	Extended LIKE clause in table definition			YES	
-T174	Identity columns			NO	
+T174	Identity columns			YES	
 T175	Generated columns			NO	
 T176	Sequence generator support			NO	
-T177	Sequence generator support: simple restart option			NO	
-T178	Identity columns:  simple restart option			NO	
+T177	Sequence generator support: simple restart option			YES	
+T178	Identity columns:  simple restart option			YES	
 T180	System-versioned tables			NO	
 T181	Application-time period tables			NO	
 T191	Referential action RESTRICT			YES	
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index d547db714e..f15141612a 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -93,7 +93,6 @@ static HTAB *seqhashtab = NULL; /* hash table for SeqTable items */
 static SeqTableData *last_used_seq = NULL;
 
 static void fill_seq_with_data(Relation rel, HeapTuple tuple);
-static int64 nextval_internal(Oid relid);
 static Relation open_share_lock(SeqTable seq);
 static void create_seq_hashtable(void);
 static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
@@ -101,9 +100,10 @@ static Form_pg_sequence_data read_seq_tuple(Relation rel,
 			   Buffer *buf, HeapTuple seqdatatuple);
 static void init_params(ParseState *pstate, List *options, bool isInit,
 						Form_pg_sequence seqform,
-						Form_pg_sequence_data seqdataform, List **owned_by);
+						Form_pg_sequence_data seqdataform, List **owned_by,
+						DependencyType *deptype);
 static void do_setval(Oid relid, int64 next, bool iscalled);
-static void process_owned_by(Relation seqrel, List *owned_by);
+static void process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype);
 
 
 /*
@@ -116,6 +116,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	FormData_pg_sequence seqform;
 	FormData_pg_sequence_data seqdataform;
 	List	   *owned_by;
+	DependencyType deptype;
 	CreateStmt *stmt = makeNode(CreateStmt);
 	Oid			seqoid;
 	ObjectAddress address;
@@ -153,7 +154,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	}
 
 	/* Check and set all option values */
-	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by);
+	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by, &deptype);
 
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
@@ -170,6 +171,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 		coldef->storage = 0;
 		coldef->raw_default = NULL;
 		coldef->cooked_default = NULL;
+		coldef->identity = ATTRIBUTE_IDENTITY_NONE;
 		coldef->collClause = NULL;
 		coldef->collOid = InvalidOid;
 		coldef->constraints = NIL;
@@ -219,7 +221,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(rel, owned_by);
+		process_owned_by(rel, owned_by, deptype);
 
 	heap_close(rel, NoLock);
 
@@ -418,6 +420,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	Form_pg_sequence_data seqdata;
 	FormData_pg_sequence_data newseqdata;
 	List	   *owned_by;
+	DependencyType deptype;
 	ObjectAddress address;
 	Relation	rel;
 	HeapTuple	tuple;
@@ -455,7 +458,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	seqform = (Form_pg_sequence) GETSTRUCT(tuple);
 
 	/* Check and set new values */
-	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by);
+	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by, &deptype);
 
 	/* Clear local cache so that we don't think we have cached numbers */
 	/* Note that we do not change the currval() state */
@@ -498,7 +501,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(seqrel, owned_by);
+		process_owned_by(seqrel, owned_by, deptype);
 
 	InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
@@ -554,7 +557,7 @@ nextval(PG_FUNCTION_ARGS)
 	 */
 	relid = RangeVarGetRelid(sequence, NoLock, false);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
 Datum
@@ -562,11 +565,11 @@ nextval_oid(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
-static int64
-nextval_internal(Oid relid)
+int64
+nextval_internal(Oid relid, bool check_permissions)
 {
 	SeqTable	elm;
 	Relation	seqrel;
@@ -592,7 +595,8 @@ nextval_internal(Oid relid)
 	/* open and AccessShareLock sequence */
 	init_sequence(relid, &elm, &seqrel);
 
-	if (pg_class_aclcheck(elm->relid, GetUserId(),
+	if (check_permissions &&
+		pg_class_aclcheck(elm->relid, GetUserId(),
 						  ACL_USAGE | ACL_UPDATE) != ACLCHECK_OK)
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -1221,7 +1225,8 @@ read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
 static void
 init_params(ParseState *pstate, List *options, bool isInit,
 			Form_pg_sequence seqform,
-			Form_pg_sequence_data seqdataform, List **owned_by)
+			Form_pg_sequence_data seqdataform, List **owned_by,
+			DependencyType *deptype)
 {
 	DefElem    *as_type = NULL;
 	DefElem    *start_value = NULL;
@@ -1231,9 +1236,11 @@ init_params(ParseState *pstate, List *options, bool isInit,
 	DefElem    *min_value = NULL;
 	DefElem    *cache_value = NULL;
 	DefElem    *is_cycled = NULL;
+	DefElem	   *deptype_el = NULL;
 	ListCell   *option;
 
 	*owned_by = NIL;
+	*deptype = DEPENDENCY_AUTO;
 
 	foreach(option, options)
 	{
@@ -1320,6 +1327,28 @@ init_params(ParseState *pstate, List *options, bool isInit,
 						 parser_errposition(pstate, defel->location)));
 			*owned_by = defGetQualifiedName(defel);
 		}
+		else if (strcmp(defel->defname, "deptype") == 0)
+		{
+			if (deptype_el)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options"),
+						 parser_errposition(pstate, defel->location)));
+			deptype_el = defel;
+			*deptype = intVal(deptype_el->arg);
+		}
+		else if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			/*
+			 * The parser allows this, but it is only for identity columns, in
+			 * which case it is filtered out in parse_utilcmd.c.  We only get
+			 * here if someone puts it into a CREATE SEQUENCE.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("invalid sequence option SEQUENCE NAME"),
+					 parser_errposition(pstate, defel->location)));
+		}
 		else
 			elog(ERROR, "option \"%s\" not recognized",
 				 defel->defname);
@@ -1565,7 +1594,7 @@ init_params(ParseState *pstate, List *options, bool isInit,
  * as the sequence.
  */
 static void
-process_owned_by(Relation seqrel, List *owned_by)
+process_owned_by(Relation seqrel, List *owned_by, DependencyType deptype)
 {
 	int			nnames;
 	Relation	tablerel;
@@ -1601,6 +1630,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		/* Must be a regular or foreign table */
 		if (!(tablerel->rd_rel->relkind == RELKIND_RELATION ||
 			  tablerel->rd_rel->relkind == RELKIND_FOREIGN_TABLE ||
+			  tablerel->rd_rel->relkind == RELKIND_VIEW ||
 			  tablerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
@@ -1627,10 +1657,28 @@ process_owned_by(Relation seqrel, List *owned_by)
 	}
 
 	/*
-	 * OK, we are ready to update pg_depend.  First remove any existing AUTO
+	 * Catch user explicitly running OWNED BY on identity sequence.
+	 */
+	if (deptype == DEPENDENCY_AUTO)
+	{
+		Oid			tableId;
+		int32		colId;
+
+		if (sequenceIsOwned(RelationGetRelid(seqrel), DEPENDENCY_INTERNAL, &tableId, &colId))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot change ownership of identity sequence"),
+					 errdetail("Sequence \"%s\" is linked to table \"%s\".",
+							   RelationGetRelationName(seqrel),
+							   get_rel_name(tableId))));
+	}
+
+	/*
+	 * OK, we are ready to update pg_depend.  First remove any existing
 	 * dependencies for the sequence, then optionally add a new one.
 	 */
-	markSequenceUnowned(RelationGetRelid(seqrel));
+	deleteDependencyRecordsForClass(RelationRelationId, RelationGetRelid(seqrel),
+									RelationRelationId, deptype);
 
 	if (tablerel)
 	{
@@ -1643,7 +1691,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		depobject.classId = RelationRelationId;
 		depobject.objectId = RelationGetRelid(seqrel);
 		depobject.objectSubId = 0;
-		recordDependencyOn(&depobject, &refobject, DEPENDENCY_AUTO);
+		recordDependencyOn(&depobject, &refobject, deptype);
 	}
 
 	/* Done, but hold lock until commit */
@@ -1653,6 +1701,33 @@ process_owned_by(Relation seqrel, List *owned_by)
 
 
 /*
+ * Return sequence parameters in a list of the form created by the parser.
+ */
+List *
+sequence_options(Oid relid)
+{
+	HeapTuple	pgstuple;
+	Form_pg_sequence pgsform;
+	List	   *options = NIL;
+
+	pgstuple = SearchSysCache1(SEQRELID, relid);
+	if (!HeapTupleIsValid(pgstuple))
+		elog(ERROR, "cache lookup failed for sequence %u", relid);
+	pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
+
+	options = lappend(options, makeDefElem("cache", (Node *) makeInteger(pgsform->seqcache), -1));
+	options = lappend(options, makeDefElem("cycle", (Node *) makeInteger(pgsform->seqcycle), -1));
+	options = lappend(options, makeDefElem("increment", (Node *) makeInteger(pgsform->seqincrement), -1));
+	options = lappend(options, makeDefElem("maxvalue", (Node *) makeInteger(pgsform->seqmax), -1));
+	options = lappend(options, makeDefElem("minvalue", (Node *) makeInteger(pgsform->seqmin), -1));
+	options = lappend(options, makeDefElem("start", (Node *) makeInteger(pgsform->seqstart), -1));
+
+	ReleaseSysCache(pgstuple);
+
+	return options;
+}
+
+/*
  * Return sequence parameters (formerly for use by information schema)
  */
 Datum
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 86329e5f9f..52311df655 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -361,6 +361,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@@ -696,6 +701,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1281,7 +1289,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;
 
 			foreach(seqcell, seqlist)
@@ -2078,6 +2086,12 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   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;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@@ -3217,6 +3231,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -3447,6 +3464,18 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_AddIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_ADD_CONSTR;
+			break;
+		case AT_DropIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_DROP;
+			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATPrepDropNotNull(rel, recurse, recursing);
@@ -3772,6 +3801,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@@ -5123,6 +5161,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		elog(ERROR, "cache lookup failed for relation %u", myrelid);
 	relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
 
+	/*
+	 * Cannot add identity column if table has children, because identity does
+	 * not inherit.  (Adding column and identity separately will work.)
+	 */
+	if (colDef->identity != ATTRIBUTE_IDENTITY_NONE &&
+		recurse &&
+		find_inheritance_children(myrelid, NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot recursively add identity column to table that has child tables")));
+
 	/* skip if the name already exists and if_not_exists is true */
 	if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
 	{
@@ -5175,6 +5224,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = colDef->identity;
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@@ -5481,6 +5531,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		cdef->is_local = true;
 		cdef->is_not_null = true;
 		cdef->storage = 0;
+		cdef->identity = ATTRIBUTE_IDENTITY_NONE;
 		cdef->location = -1;
 		cmd->def = (Node *) cdef;
 	}
@@ -5542,6 +5593,12 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ATTRIBUTE_IDENTITY_NONE)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Check that the attribute is not in a primary key
 	 *
@@ -5758,6 +5815,13 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum) != ATTRIBUTE_IDENTITY_NONE)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel)),
+				 newDefault ? 0 : errhint("Use ALTER TABLE ... ALTER COLUMN ... DROP IDENTITY instead.")));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@@ -5793,6 +5857,212 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	ObjectAddress address;
+	ColumnDef  *cdef = castNode(ColumnDef, def);
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	/*
+	 * Creating a column as identity implies NOT NULL, so adding the identity
+	 * to an existing column that is not NOT NULL would create a state that
+	 * cannot be reproduced without contortions.
+	 */
+	if (!attTup->attnotnull)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->attidentity != ATTRIBUTE_IDENTITY_NONE)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, castNode(List, def))
+	{
+		DefElem	   *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ATTRIBUTE_IDENTITY_NONE)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+	Oid			seqid;
+	ObjectAddress seqaddress;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (attTup->attidentity == ATTRIBUTE_IDENTITY_NONE)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = ATTRIBUTE_IDENTITY_NONE;
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	/* drop the internal sequence */
+	seqid = getOwnedSequence(RelationGetRelid(rel), attnum);
+	deleteDependencyRecordsForClass(RelationRelationId, seqid,
+									RelationRelationId, DEPENDENCY_INTERNAL);
+	CommandCounterIncrement();
+	seqaddress.classId = RelationRelationId;
+	seqaddress.objectId = seqid;
+	seqaddress.objectSubId = 0;
+	performDeletion(&seqaddress, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET STATISTICS
  */
 static void
@@ -9540,7 +9810,8 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 				Oid			tableId;
 				int32		colId;
 
-				if (sequenceIsOwned(relationOid, &tableId, &colId))
+				if (sequenceIsOwned(relationOid, DEPENDENCY_AUTO, &tableId, &colId) ||
+					sequenceIsOwned(relationOid, DEPENDENCY_INTERNAL, &tableId, &colId))
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 							 errmsg("cannot change owner of sequence \"%s\"",
@@ -9811,7 +10082,7 @@ change_owner_recurse_to_sequences(Oid relationOid, Oid newOwnerId, LOCKMODE lock
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;
 
 		/* Use relation_open just in case it's an index */
@@ -12116,7 +12387,8 @@ AlterTableNamespace(AlterObjectSchemaStmt *stmt, Oid *oldschema)
 		Oid			tableId;
 		int32		colId;
 
-		if (sequenceIsOwned(relid, &tableId, &colId))
+		if (sequenceIsOwned(relid, DEPENDENCY_AUTO, &tableId, &colId) ||
+			sequenceIsOwned(relid, DEPENDENCY_INTERNAL, &tableId, &colId))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot move an owned sequence into another schema"),
@@ -12299,7 +12571,7 @@ AlterIndexNamespaces(Relation classRel, Relation rel,
 }
 
 /*
- * Move all SERIAL-column sequences of the specified relation to another
+ * Move all identity and SERIAL-column sequences of the specified relation to another
  * namespace.
  *
  * Note: we assume adequate permission checking was done by the caller,
@@ -12343,7 +12615,7 @@ AlterSeqNamespaces(Relation classRel, Relation rel,
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;
 
 		/* Use relation_open just in case it's an index */
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 90bef6f01f..34dde8957a 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -41,6 +41,7 @@
 #include "access/tupconvert.h"
 #include "catalog/objectaccess.h"
 #include "catalog/pg_type.h"
+#include "commands/sequence.h"
 #include "executor/execdebug.h"
 #include "executor/nodeSubplan.h"
 #include "funcapi.h"
@@ -182,6 +183,8 @@ static Datum ExecEvalArrayCoerceExpr(ArrayCoerceExprState *astate,
 						bool *isNull);
 static Datum ExecEvalCurrentOfExpr(ExprState *exprstate, ExprContext *econtext,
 					  bool *isNull);
+static Datum ExecEvalNextValueExpr(ExprState *exprstate, ExprContext *econtext,
+								   bool *isNull);
 static Datum ExecEvalGroupingFuncExpr(GroupingFuncExprState *gstate,
 						 ExprContext *econtext,
 						 bool *isNull);
@@ -4212,6 +4215,20 @@ ExecEvalCurrentOfExpr(ExprState *exprstate, ExprContext *econtext,
 
 
 /*
+ * ExecEvalNextValueExpr
+ */
+static Datum
+ExecEvalNextValueExpr(ExprState *exprstate, ExprContext *econtext,
+					  bool *isNull)
+{
+	NextValueExpr *nve = (NextValueExpr *) exprstate->expr;
+
+	*isNull = false;
+	return Int64GetDatum(nextval_internal(nve->seqid, false));
+}
+
+
+/*
  * ExecEvalExprSwitchContext
  *
  * Same as ExecEvalExpr, but get into the right allocation context explicitly.
@@ -4953,6 +4970,10 @@ ExecInitExpr(Expr *node, PlanState *parent)
 			state = makeNode(ExprState);
 			state->evalfunc = ExecEvalCurrentOfExpr;
 			break;
+		case T_NextValueExpr:
+			state = (ExprState *) makeNode(ExprState);
+			state->evalfunc = (ExprStateEvalFunc) ExecEvalNextValueExpr;
+			break;
 		case T_TargetEntry:
 			{
 				TargetEntry *tle = (TargetEntry *) node;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index c799e3112c..6789e8791a 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1978,6 +1978,20 @@ _copyCurrentOfExpr(const CurrentOfExpr *from)
 	return newnode;
 }
 
+ /*
+  * _copyNextValueExpr
+  */
+static NextValueExpr *
+_copyNextValueExpr(const NextValueExpr *from)
+{
+	NextValueExpr *newnode = makeNode(NextValueExpr);
+
+	COPY_SCALAR_FIELD(seqid);
+	COPY_SCALAR_FIELD(typeId);
+
+	return newnode;
+}
+
 /*
  * _copyInferenceElem
  */
@@ -2750,6 +2764,7 @@ _copyColumnDef(const ColumnDef *from)
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_SCALAR_FIELD(identity);
 	COPY_NODE_FIELD(collClause);
 	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
@@ -2772,6 +2787,7 @@ _copyConstraint(const Constraint *from)
 	COPY_SCALAR_FIELD(is_no_inherit);
 	COPY_NODE_FIELD(raw_expr);
 	COPY_STRING_FIELD(cooked_expr);
+	COPY_SCALAR_FIELD(generated_when);
 	COPY_NODE_FIELD(keys);
 	COPY_NODE_FIELD(exclusions);
 	COPY_NODE_FIELD(options);
@@ -2880,6 +2896,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
 	COPY_NODE_FIELD(targetList);
+	COPY_SCALAR_FIELD(override);
 	COPY_NODE_FIELD(onConflict);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(groupClause);
@@ -2923,6 +2940,7 @@ _copyInsertStmt(const InsertStmt *from)
 	COPY_NODE_FIELD(onConflictClause);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(withClause);
+	COPY_SCALAR_FIELD(override);
 
 	return newnode;
 }
@@ -4857,6 +4875,9 @@ copyObject(const void *from)
 		case T_CurrentOfExpr:
 			retval = _copyCurrentOfExpr(from);
 			break;
+		case T_NextValueExpr:
+			retval = _copyNextValueExpr(from);
+			break;
 		case T_InferenceElem:
 			retval = _copyInferenceElem(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index b230f65e03..76efac2dc3 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -734,6 +734,15 @@ _equalCurrentOfExpr(const CurrentOfExpr *a, const CurrentOfExpr *b)
 }
 
 static bool
+_equalNextValueExpr(const NextValueExpr *a, const NextValueExpr *b)
+{
+	COMPARE_SCALAR_FIELD(seqid);
+	COMPARE_SCALAR_FIELD(typeId);
+
+	return true;
+}
+
+static bool
 _equalInferenceElem(const InferenceElem *a, const InferenceElem *b)
 {
 	COMPARE_NODE_FIELD(expr);
@@ -954,6 +963,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
 	COMPARE_NODE_FIELD(targetList);
+	COMPARE_SCALAR_FIELD(override);
 	COMPARE_NODE_FIELD(onConflict);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(groupClause);
@@ -993,6 +1003,7 @@ _equalInsertStmt(const InsertStmt *a, const InsertStmt *b)
 	COMPARE_NODE_FIELD(onConflictClause);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(withClause);
+	COMPARE_SCALAR_FIELD(override);
 
 	return true;
 }
@@ -2498,6 +2509,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_SCALAR_FIELD(identity);
 	COMPARE_NODE_FIELD(collClause);
 	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
@@ -2518,6 +2530,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_SCALAR_FIELD(is_no_inherit);
 	COMPARE_NODE_FIELD(raw_expr);
 	COMPARE_STRING_FIELD(cooked_expr);
+	COMPARE_SCALAR_FIELD(generated_when);
 	COMPARE_NODE_FIELD(keys);
 	COMPARE_NODE_FIELD(exclusions);
 	COMPARE_NODE_FIELD(options);
@@ -3067,6 +3080,9 @@ equal(const void *a, const void *b)
 		case T_CurrentOfExpr:
 			retval = _equalCurrentOfExpr(a, b);
 			break;
+		case T_NextValueExpr:
+			retval = _equalNextValueExpr(a, b);
+			break;
 		case T_InferenceElem:
 			retval = _equalInferenceElem(a, b);
 			break;
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index e88d82f3b0..5a8775309f 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -15,6 +15,7 @@
  */
 #include "postgres.h"
 
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_type.h"
 #include "fmgr.h"
@@ -497,6 +498,7 @@ makeColumnDef(const char *colname, Oid typeOid, int32 typmod, Oid collOid)
 	n->storage = 0;
 	n->raw_default = NULL;
 	n->cooked_default = NULL;
+	n->identity = ATTRIBUTE_IDENTITY_NONE;
 	n->collClause = NULL;
 	n->collOid = collOid;
 	n->constraints = NIL;
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 6e52eb7231..31714fd466 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -246,6 +246,9 @@ exprType(const Node *expr)
 		case T_CurrentOfExpr:
 			type = BOOLOID;
 			break;
+		case T_NextValueExpr:
+			type = ((const NextValueExpr *) expr)->typeId;
+			break;
 		case T_InferenceElem:
 			{
 				const InferenceElem *n = (const InferenceElem *) expr;
@@ -919,6 +922,9 @@ exprCollation(const Node *expr)
 		case T_CurrentOfExpr:
 			coll = InvalidOid;	/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			coll = InvalidOid;	/* result is always an integer type */
+			break;
 		case T_InferenceElem:
 			coll = exprCollation((Node *) ((const InferenceElem *) expr)->expr);
 			break;
@@ -1122,6 +1128,9 @@ exprSetCollation(Node *expr, Oid collation)
 		case T_CurrentOfExpr:
 			Assert(!OidIsValid(collation));		/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			Assert(!OidIsValid(collation));		/* result is always an integer type */
+			break;
 		default:
 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
 			break;
@@ -1881,6 +1890,7 @@ expression_tree_walker(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
@@ -2475,6 +2485,7 @@ expression_tree_mutator(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 7418fbeded..1e7cf3252f 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2686,6 +2686,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_CHAR_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_CHAR_FIELD(identity);
 	WRITE_NODE_FIELD(collClause);
 	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
@@ -2791,6 +2792,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
 	WRITE_NODE_FIELD(targetList);
+	WRITE_ENUM_FIELD(override, OverridingKind);
 	WRITE_NODE_FIELD(onConflict);
 	WRITE_NODE_FIELD(returningList);
 	WRITE_NODE_FIELD(groupClause);
@@ -3321,6 +3323,13 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_STRING_FIELD(cooked_expr);
 			break;
 
+		case CONSTR_IDENTITY:
+			appendStringInfoString(str, "IDENTITY");
+			WRITE_NODE_FIELD(raw_expr);
+			WRITE_STRING_FIELD(cooked_expr);
+			WRITE_CHAR_FIELD(generated_when);
+			break;
+
 		case CONSTR_CHECK:
 			appendStringInfoString(str, "CHECK");
 			WRITE_BOOL_FIELD(is_no_inherit);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index d3bbc02f24..f8595b7f32 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -247,6 +247,7 @@ _readQuery(void)
 	READ_NODE_FIELD(rtable);
 	READ_NODE_FIELD(jointree);
 	READ_NODE_FIELD(targetList);
+	READ_ENUM_FIELD(override, OverridingKind);
 	READ_NODE_FIELD(onConflict);
 	READ_NODE_FIELD(returningList);
 	READ_NODE_FIELD(groupClause);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 3571e50aea..e2bcca5061 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -484,6 +484,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
 	}
 
+	qry->override = stmt->override;
+
 	isOnConflictUpdate = (stmt->onConflictClause &&
 						stmt->onConflictClause->action == ONCONFLICT_UPDATE);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index d0d45a557b..855f0d5e49 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -51,6 +51,7 @@
 #include "catalog/index.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_am.h"
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_trigger.h"
 #include "commands/defrem.h"
 #include "commands/trigger.h"
@@ -292,6 +293,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity partition_cmd
 %type <list>	alter_table_cmds alter_type_cmds
+%type <list>    alter_identity_column_option_list
+%type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -449,7 +452,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				select_offset_value2 opt_select_fetch_first_value
 %type <ival>	row_or_rows first_or_next
 
-%type <list>	OptSeqOptList SeqOptList
+%type <list>	OptSeqOptList SeqOptList OptParenthesizedSeqOptList
 %type <defelt>	SeqOptElem
 
 %type <istmt>	insert_rest
@@ -569,6 +572,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_frame_clause frame_extent frame_bound
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
+%type <ival>	generated_when override_kind
 %type <partspec>	PartitionSpec OptPartitionSpec
 %type <str>			part_strategy
 %type <partelem>	part_elem
@@ -631,7 +635,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
 	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
-	GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
+	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
 
 	HANDLER HAVING HEADER_P HOLD HOUR_P
 
@@ -655,7 +659,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	NULLS_P NUMERIC
 
 	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OPTIONS OR
-	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
+	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
 	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
@@ -726,6 +730,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * same as if they weren't keywords).  We need to do this for PARTITION,
  * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
  * so that they can follow a_expr without creating postfix-operator problems;
+ * for GENERATED so that it can follow b_expr;
  * and for NULL so that it can follow b_expr in ColQualList without creating
  * postfix-operator problems.
  *
@@ -744,7 +749,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * blame any funny behavior of UNBOUNDED on the SQL standard, though.
  */
 %nonassoc	UNBOUNDED		/* ideally should have same precedence as IDENT */
-%nonassoc	IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
+%nonassoc	IDENT GENERATED NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %left		'+' '-'
 %left		'*' '/' '%'
@@ -2126,6 +2131,40 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
+			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					Constraint *c = makeNode(Constraint);
+
+					c->contype = CONSTR_IDENTITY;
+					c->generated_when = $6;
+					c->options = $9;
+					c->location = @5;
+
+					n->subtype = AT_AddIdentity;
+					n->name = $3;
+					n->def = (Node *) c;
+
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
+			| ALTER opt_column ColId alter_identity_column_option_list
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->def = (Node *) $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
+			| ALTER opt_column ColId DROP IDENTITY_P
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
@@ -2563,6 +2602,39 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_option_list:
+			alter_identity_column_option
+				{ $$ = list_make1($1); }
+			| alter_identity_column_option_list alter_identity_column_option
+				{ $$ = lappend($1, $2); }
+		;
+
+alter_identity_column_option:
+			RESTART
+				{
+					$$ = makeDefElem("restart", NULL, @1);
+				}
+			| RESTART opt_with NumericOnly
+				{
+					$$ = makeDefElem("restart", (Node *)$3, @1);
+				}
+			| SET SeqOptElem
+				{
+					if (strcmp($2->defname, "as") == 0 ||
+						strcmp($2->defname, "restart") == 0 ||
+						strcmp($2->defname, "owned_by") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("sequence option \"%s\" not supported here", $2->defname),
+								 parser_errposition(@2)));
+					$$ = $2;
+				}
+			| SET GENERATED generated_when
+				{
+					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
+				}
+		;
+
 ForValues:
 			/* a LIST partition */
 			FOR VALUES IN_P '(' partbound_datum_list ')'
@@ -3213,6 +3285,7 @@ columnDef:	ColId Typename create_generic_options ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ATTRIBUTE_IDENTITY_NONE;
 					n->collOid = InvalidOid;
 					n->fdwoptions = $3;
 					SplitColQualList($4, &n->constraints, &n->collClause,
@@ -3234,6 +3307,7 @@ columnOptions:	ColId WITH OPTIONS ColQualList
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ATTRIBUTE_IDENTITY_NONE;
 					n->collOid = InvalidOid;
 					SplitColQualList($4, &n->constraints, &n->collClause,
 									 yyscanner);
@@ -3345,6 +3419,15 @@ ColConstraintElem:
 					n->cooked_expr = NULL;
 					$$ = (Node *)n;
 				}
+			| GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					Constraint *n = makeNode(Constraint);
+					n->contype = CONSTR_IDENTITY;
+					n->generated_when = $2;
+					n->options = $5;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
 			| REFERENCES qualified_name opt_column_list key_match key_actions
 				{
 					Constraint *n = makeNode(Constraint);
@@ -3362,6 +3445,11 @@ ColConstraintElem:
 				}
 		;
 
+generated_when:
+			ALWAYS			{ $$ = ATTRIBUTE_IDENTITY_ALWAYS; }
+			| BY DEFAULT	{ $$ = ATTRIBUTE_IDENTITY_BY_DEFAULT; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -3428,6 +3516,7 @@ TableLikeOptionList:
 TableLikeOption:
 				DEFAULTS			{ $$ = CREATE_TABLE_LIKE_DEFAULTS; }
 				| CONSTRAINTS		{ $$ = CREATE_TABLE_LIKE_CONSTRAINTS; }
+				| IDENTITY_P		{ $$ = CREATE_TABLE_LIKE_IDENTITY; }
 				| INDEXES			{ $$ = CREATE_TABLE_LIKE_INDEXES; }
 				| STORAGE			{ $$ = CREATE_TABLE_LIKE_STORAGE; }
 				| COMMENTS			{ $$ = CREATE_TABLE_LIKE_COMMENTS; }
@@ -3936,6 +4025,10 @@ OptSeqOptList: SeqOptList							{ $$ = $1; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+OptParenthesizedSeqOptList: '(' SeqOptList ')'		{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
@@ -3980,6 +4073,11 @@ SeqOptElem: AS SimpleTypename
 				{
 					$$ = makeDefElem("owned_by", (Node *)$3, @1);
 				}
+			| SEQUENCE NAME_P any_name
+				{
+					/* not documented, only used by pg_dump */
+					$$ = makeDefElem("sequence_name", (Node *)$3, @1);
+				}
 			| START opt_with NumericOnly
 				{
 					$$ = makeDefElem("start", (Node *)$3, @1);
@@ -10309,12 +10407,26 @@ insert_rest:
 					$$->cols = NIL;
 					$$->selectStmt = $1;
 				}
+			| OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = NIL;
+					$$->override = $2;
+					$$->selectStmt = $4;
+				}
 			| '(' insert_column_list ')' SelectStmt
 				{
 					$$ = makeNode(InsertStmt);
 					$$->cols = $2;
 					$$->selectStmt = $4;
 				}
+			| '(' insert_column_list ')' OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = $2;
+					$$->override = $5;
+					$$->selectStmt = $7;
+				}
 			| DEFAULT VALUES
 				{
 					$$ = makeNode(InsertStmt);
@@ -10323,6 +10435,11 @@ insert_rest:
 				}
 		;
 
+override_kind:
+			USER		{ $$ = OVERRIDING_USER_VALUE; }
+			| SYSTEM_P	{ $$ = OVERRIDING_SYSTEM_VALUE; }
+		;
+
 insert_column_list:
 			insert_column_item
 					{ $$ = list_make1($1); }
@@ -11686,6 +11803,7 @@ TableFuncElement:	ColId Typename opt_collate_clause
 					n->storage = 0;
 					n->raw_default = NULL;
 					n->cooked_default = NULL;
+					n->identity = ATTRIBUTE_IDENTITY_NONE;
 					n->collClause = (CollateClause *) $3;
 					n->collOid = InvalidOid;
 					n->constraints = NIL;
@@ -14494,6 +14612,7 @@ unreserved_keyword:
 			| FORWARD
 			| FUNCTION
 			| FUNCTIONS
+			| GENERATED
 			| GLOBAL
 			| GRANTED
 			| HANDLER
@@ -14562,6 +14681,7 @@ unreserved_keyword:
 			| OPTIONS
 			| ORDINALITY
 			| OVER
+			| OVERRIDING
 			| OWNED
 			| OWNER
 			| PARALLEL
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 673276a9d3..58578fa0da 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -42,6 +42,7 @@
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
@@ -356,6 +357,130 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	return result;
 }
 
+static void
+generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
+						 Oid seqtypid, List *seqoptions, DependencyType deptype,
+						 char **snamespace_p, char **sname_p)
+{
+	ListCell   *option;
+	DefElem	   *nameEl = NULL;
+	Oid			snamespaceid;
+	char	   *snamespace;
+	char	   *sname;
+	CreateSeqStmt *seqstmt;
+	AlterSeqStmt *altseqstmt;
+	List	   *attnamelist;
+
+	/*
+	 * Determine namespace and name to use for the sequence.
+	 *
+	 * First, check if a sequence name was passed in as an option.  This is
+	 * used by pg_dump.  Else, generate a name.
+	 *
+	 * Although we use ChooseRelationName, it's not guaranteed that the
+	 * selected sequence name won't conflict; given sufficiently long
+	 * field names, two different serial columns in the same table could
+	 * be assigned the same sequence name, and we'd not notice since we
+	 * aren't creating the sequence quite yet.  In practice this seems
+	 * quite unlikely to be a problem, especially since few people would
+	 * need two serial columns in one table.
+	 */
+
+	foreach(option, seqoptions)
+	{
+		DefElem    *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			if (nameEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			nameEl = defel;
+		}
+	}
+
+	if (nameEl)
+	{
+		RangeVar *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));
+		snamespace = rv->schemaname;
+		sname = rv->relname;
+		seqoptions = list_delete_ptr(seqoptions, nameEl);
+	}
+	else
+	{
+		if (cxt->rel)
+			snamespaceid = RelationGetNamespace(cxt->rel);
+		else
+		{
+			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
+			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
+		}
+		snamespace = get_namespace_name(snamespaceid);
+		sname = ChooseRelationName(cxt->relation->relname,
+								   column->colname,
+								   "seq",
+								   snamespaceid);
+	}
+
+	ereport(DEBUG1,
+			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
+					cxt->stmtType, sname,
+					cxt->relation->relname, column->colname)));
+
+	/*
+	 * Build a CREATE SEQUENCE command to create the sequence object, and
+	 * add it to the list of things to be done before this CREATE/ALTER
+	 * TABLE.
+	 */
+	seqstmt = makeNode(CreateSeqStmt);
+	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->options = seqoptions;
+	/*
+	 * If a sequence data type was specified, add it to the options.  Prepend
+	 * to the list rather than append; in case a user supplied their own AS
+	 * clause, the "redundant options" error will point to their occurrence,
+	 * not our synthetic one.
+	 */
+	if (seqtypid)
+		seqstmt->options = lcons(makeDefElem("as", (Node *) makeTypeNameFromOid(seqtypid, -1), -1),
+								 seqstmt->options);
+
+	/*
+	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
+	 * by the table's owner.  The current user might be someone else
+	 * (perhaps a superuser, or someone who's only a member of the owning
+	 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
+	 * and sequence have exactly the same owning role.
+	 */
+	if (cxt->rel)
+		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
+	else
+		seqstmt->ownerId = InvalidOid;
+
+	cxt->blist = lappend(cxt->blist, seqstmt);
+
+	/*
+	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
+	 * as owned by this column, and add it to the list of things to be
+	 * done after this CREATE/ALTER TABLE.
+	 */
+	altseqstmt = makeNode(AlterSeqStmt);
+	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	attnamelist = list_make3(makeString(snamespace),
+							 makeString(cxt->relation->relname),
+							 makeString(column->colname));
+	altseqstmt->options = list_make2(makeDefElem("owned_by",
+												 (Node *) attnamelist, -1),
+									 makeDefElem("deptype",
+												 (Node *) makeInteger(deptype), -1));
+
+	cxt->alist = lappend(cxt->alist, altseqstmt);
+
+	*snamespace_p = snamespace;
+	*sname_p = sname;
+}
+
 /*
  * transformColumnDefinition -
  *		transform a single ColumnDef within CREATE TABLE
@@ -367,7 +492,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	bool		is_serial;
 	bool		saw_nullable;
 	bool		saw_default;
-	Constraint *constraint;
+	bool		saw_identity;
 	ListCell   *clist;
 
 	cxt->columns = lappend(cxt->columns, column);
@@ -422,83 +547,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	/* Special actions for SERIAL pseudo-types */
 	if (is_serial)
 	{
-		Oid			snamespaceid;
 		char	   *snamespace;
 		char	   *sname;
 		char	   *qstring;
 		A_Const    *snamenode;
 		TypeCast   *castnode;
 		FuncCall   *funccallnode;
-		CreateSeqStmt *seqstmt;
-		AlterSeqStmt *altseqstmt;
-		List	   *attnamelist;
-
-		/*
-		 * Determine namespace and name to use for the sequence.
-		 *
-		 * Although we use ChooseRelationName, it's not guaranteed that the
-		 * selected sequence name won't conflict; given sufficiently long
-		 * field names, two different serial columns in the same table could
-		 * be assigned the same sequence name, and we'd not notice since we
-		 * aren't creating the sequence quite yet.  In practice this seems
-		 * quite unlikely to be a problem, especially since few people would
-		 * need two serial columns in one table.
-		 */
-		if (cxt->rel)
-			snamespaceid = RelationGetNamespace(cxt->rel);
-		else
-		{
-			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
-			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
-		}
-		snamespace = get_namespace_name(snamespaceid);
-		sname = ChooseRelationName(cxt->relation->relname,
-								   column->colname,
-								   "seq",
-								   snamespaceid);
-
-		ereport(DEBUG1,
-				(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
-						cxt->stmtType, sname,
-						cxt->relation->relname, column->colname)));
-
-		/*
-		 * Build a CREATE SEQUENCE command to create the sequence object, and
-		 * add it to the list of things to be done before this CREATE/ALTER
-		 * TABLE.
-		 */
-		seqstmt = makeNode(CreateSeqStmt);
-		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(column->typeName->typeOid, -1), -1));
+		Constraint *constraint;
 
-		/*
-		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
-		 * by the table's owner.  The current user might be someone else
-		 * (perhaps a superuser, or someone who's only a member of the owning
-		 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
-		 * and sequence have exactly the same owning role.
-		 */
-		if (cxt->rel)
-			seqstmt->ownerId = cxt->rel->rd_rel->relowner;
-		else
-			seqstmt->ownerId = InvalidOid;
-
-		cxt->blist = lappend(cxt->blist, seqstmt);
-
-		/*
-		 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
-		 * as owned by this column, and add it to the list of things to be
-		 * done after this CREATE/ALTER TABLE.
-		 */
-		altseqstmt = makeNode(AlterSeqStmt);
-		altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		attnamelist = list_make3(makeString(snamespace),
-								 makeString(cxt->relation->relname),
-								 makeString(column->colname));
-		altseqstmt->options = list_make1(makeDefElem("owned_by",
-												  (Node *) attnamelist, -1));
-
-		cxt->alist = lappend(cxt->alist, altseqstmt);
+		generateSerialExtraStmts(cxt, column,
+								 column->typeName->typeOid, NIL, DEPENDENCY_AUTO,
+								 &snamespace, &sname);
 
 		/*
 		 * Create appropriate constraints for SERIAL.  We do this in full,
@@ -540,10 +599,11 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
 	saw_nullable = false;
 	saw_default = false;
+	saw_identity = false;
 
 	foreach(clist, column->constraints)
 	{
-		constraint = castNode(Constraint, lfirst(clist));
+		Constraint *constraint = castNode(Constraint, lfirst(clist));
 
 		switch (constraint->contype)
 		{
@@ -581,9 +641,44 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 												constraint->location)));
 				column->raw_default = constraint->raw_expr;
 				Assert(constraint->cooked_expr == NULL);
+				column->identity = ATTRIBUTE_IDENTITY_NONE;
 				saw_default = true;
 				break;
 
+			case CONSTR_IDENTITY:
+			{
+				char	   *snamespace;
+				char	   *sname;
+				Type		ctype;
+				Oid			typeOid;
+
+				ctype = typenameType(cxt->pstate, column->typeName, NULL);
+				typeOid = HeapTupleGetOid(ctype);
+				ReleaseSysCache(ctype);
+
+				if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+					ereport(ERROR,
+							(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+							 errmsg("identity column type must be smallint, integer, or bigint")));
+
+				if (saw_identity)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
+									column->colname, cxt->relation->relname),
+							 parser_errposition(cxt->pstate,
+												constraint->location)));
+
+				generateSerialExtraStmts(cxt, column,
+										 typeOid, constraint->options, DEPENDENCY_INTERNAL,
+										 &snamespace, &sname);
+
+				column->identity = constraint->generated_when;
+				saw_identity = true;
+				column->is_not_null = TRUE;
+				break;
+			}
+
 			case CONSTR_CHECK:
 				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
 				break;
@@ -660,6 +755,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 					 constraint->contype);
 				break;
 		}
+
+		if (saw_default && saw_identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
+							column->colname, cxt->relation->relname),
+					 parser_errposition(cxt->pstate,
+										constraint->location)));
 	}
 
 	/*
@@ -889,6 +992,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		def->storage = 0;
 		def->raw_default = NULL;
 		def->cooked_default = NULL;
+		def->identity = ATTRIBUTE_IDENTITY_NONE;
 		def->collClause = NULL;
 		def->collOid = attribute->attcollation;
 		def->constraints = NIL;
@@ -904,7 +1008,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 		/*
 		 * Copy default, if present and the default has been requested
 		 */
-		if (attribute->atthasdef &&
+		if (attribute->atthasdef && attribute->attidentity == ATTRIBUTE_IDENTITY_NONE &&
 			(table_like_clause->options & CREATE_TABLE_LIKE_DEFAULTS))
 		{
 			Node	   *this_default = NULL;
@@ -932,6 +1036,29 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			def->cooked_default = this_default;
 		}
 
+		/*
+		 * Copy identity if requested
+		 */
+		if (attribute->attidentity != ATTRIBUTE_IDENTITY_NONE &&
+			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
+		{
+			Oid         seq_relid;
+			List	   *seq_options;
+			char	   *snamespace;
+			char	   *sname;
+
+			/*
+			 * find sequence owned by old column; extract sequence parameters;
+			 * build new create sequence command
+			 */
+			seq_relid = getOwnedSequence(RelationGetRelid(relation), attribute->attnum);
+			seq_options = sequence_options(seq_relid);
+			generateSerialExtraStmts(cxt, def,
+									 InvalidOid, seq_options, DEPENDENCY_INTERNAL,
+									 &snamespace, &sname);
+			def->identity = attribute->attidentity;
+		}
+
 		/* Likewise, copy storage if requested */
 		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
 			def->storage = attribute->attstorage;
@@ -1106,6 +1233,7 @@ transformOfType(CreateStmtContext *cxt, TypeName *ofTypename)
 		n->storage = 0;
 		n->raw_default = NULL;
 		n->cooked_default = NULL;
+		n->identity = ATTRIBUTE_IDENTITY_NONE;
 		n->collClause = NULL;
 		n->collOid = attr->attcollation;
 		n->constraints = NIL;
@@ -2628,6 +2756,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 			case AT_AlterColumnType:
 				{
 					ColumnDef  *def = (ColumnDef *) cmd->def;
+					AttrNumber	attnum;
 
 					/*
 					 * For ALTER COLUMN TYPE, transform the USING clause if
@@ -2640,6 +2769,110 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 										  EXPR_KIND_ALTER_COL_TRANSFORM);
 					}
 
+					/*
+					 * For identity column, create ALTER SEQUENCE command to
+					 * change the data type of the sequence.
+					 */
+					attnum = get_attnum(relid, cmd->name);
+					/* if attribute not found, something will error about it later */
+					if (attnum != InvalidAttrNumber && get_attidentity(relid, attnum) != ATTRIBUTE_IDENTITY_NONE)
+					{
+						Oid			seq_relid = getOwnedSequence(relid, attnum);
+						Oid			typeOid = typenameTypeId(pstate, def->typeName);
+						AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
+
+						if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+							ereport(ERROR,
+									(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+									 errmsg("identity column type must be smallint, integer, or bigint")));
+
+						altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															get_rel_name(seq_relid),
+															-1);
+						altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
+						cxt.blist = lappend(cxt.blist, altseqstmt);
+					}
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_AddIdentity:
+				{
+					Constraint  *def = castNode(Constraint, cmd->def);
+					ColumnDef *newdef = makeNode(ColumnDef);
+					Oid			typeOid;
+					char	   *snamespace;
+					char	   *sname;
+
+					typeOid = get_atttype(relid, get_attnum(relid, cmd->name));
+					if (!(typeOid == INT2OID || typeOid == INT4OID || typeOid == INT8OID))
+						ereport(ERROR,
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("identity column type must be smallint, integer, or bigint")));
+
+					newdef->colname = cmd->name;
+					newdef->identity = def->generated_when;
+					cmd->def = (Node *) newdef;
+
+					generateSerialExtraStmts(&cxt, newdef,
+											 typeOid, def->options, DEPENDENCY_INTERNAL,
+											 &snamespace, &sname);
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_SetIdentity:
+				{
+					/*
+					 * Create an ALTER SEQUENCE statement for the internal
+					 * sequence of the identity column.
+					 */
+					ListCell   *lc;
+					List	   *newseqopts = NIL;
+					List	   *newdef = NIL;
+					List	   *seqlist;
+					AttrNumber	attnum;
+
+					/*
+					 * Split options into those handled by ALTER SEQUENCE and
+					 * those for ALTER TABLE proper.
+					 */
+					foreach(lc, castNode(List, cmd->def))
+					{
+						DefElem	   *def = castNode(DefElem, lfirst(lc));
+
+						if (strcmp(def->defname, "generated") == 0)
+							newdef = lappend(newdef, def);
+						else
+							newseqopts = lappend(newseqopts, def);
+					}
+
+					attnum = get_attnum(relid, cmd->name);
+
+					if (attnum)
+					{
+						seqlist = getOwnedSequences(relid, attnum);
+						if (seqlist)
+						{
+							AlterSeqStmt *seqstmt;
+							Oid			seq_relid;
+
+							seqstmt = makeNode(AlterSeqStmt);
+							seq_relid = linitial_oid(seqlist);
+							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															 get_rel_name(seq_relid), -1);
+							seqstmt->options = newseqopts;
+							seqstmt->missing_ok = false;
+
+							cxt.alist = lappend(cxt.alist, seqstmt);
+						}
+					}
+					/* If column was not found or was not an identity column, we
+					 * just let the ALTER TABLE command error out later. */
+
+					cmd->def = (Node *) newdef;
 					newcmds = lappend(newcmds, cmd);
 					break;
 				}
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 354e5d0462..3781326ea0 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -21,6 +21,7 @@
 #include "postgres.h"
 
 #include "access/sysattr.h"
+#include "catalog/dependency.h"
 #include "catalog/pg_type.h"
 #include "commands/trigger.h"
 #include "foreign/fdwapi.h"
@@ -61,6 +62,7 @@ static Query *rewriteRuleAction(Query *parsetree,
 static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static List *rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list);
@@ -709,6 +711,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 static List *
 rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list)
@@ -789,6 +792,7 @@ rewriteTargetListIU(List *targetList,
 	for (attrno = 1; attrno <= numattrs; attrno++)
 	{
 		TargetEntry *new_tle = new_tles[attrno - 1];
+		bool	apply_default;
 
 		att_tup = target_relation->rd_att->attrs[attrno - 1];
 
@@ -801,12 +805,51 @@ rewriteTargetListIU(List *targetList,
 		 * it's an INSERT and there's no tlist entry for the column, or the
 		 * tlist entry is a DEFAULT placeholder node.
 		 */
-		if ((new_tle == NULL && commandType == CMD_INSERT) ||
-			(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
+		apply_default = ((new_tle == NULL && commandType == CMD_INSERT) ||
+						 (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
+
+		if (commandType == CMD_INSERT)
+		{
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
+			{
+				if (override != OVERRIDING_SYSTEM_VALUE)
+					ereport(ERROR,
+							(errcode(ERRCODE_GENERATED_ALWAYS),
+							 errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
+							 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+									   NameStr(att_tup->attname)),
+							 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
+			}
+
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_BY_DEFAULT && override == OVERRIDING_USER_VALUE)
+				apply_default = true;
+		}
+
+		if (commandType == CMD_UPDATE)
+		{
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
+				ereport(ERROR,
+						(errcode(ERRCODE_GENERATED_ALWAYS),
+						 errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
+						 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+								   NameStr(att_tup->attname))));
+		}
+
+		if (apply_default)
 		{
 			Node	   *new_expr;
 
-			new_expr = build_column_default(target_relation, attrno);
+			if (att_tup->attidentity != ' ')
+			{
+				NextValueExpr *nve = makeNode(NextValueExpr);
+
+				nve->seqid = getOwnedSequence(RelationGetRelid(target_relation), attrno);
+				nve->typeId = att_tup->atttypid;
+
+				new_expr = (Node *) nve;
+			}
+			else
+				new_expr = build_column_default(target_relation, attrno);
 
 			/*
 			 * If there is no default (ie, default is effectively NULL), we
@@ -3232,6 +3275,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				/* Process the main targetlist ... */
 				parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
 													  parsetree->commandType,
+															parsetree->override,
 															rt_entry_relation,
 												   parsetree->resultRelation,
 															&attrnos);
@@ -3244,6 +3288,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->targetList =
 					rewriteTargetListIU(parsetree->targetList,
 										parsetree->commandType,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation, NULL);
 			}
@@ -3254,6 +3299,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->onConflict->onConflictSet =
 					rewriteTargetListIU(parsetree->onConflict->onConflictSet,
 										CMD_UPDATE,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation,
 										NULL);
@@ -3263,7 +3309,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 		{
 			parsetree->targetList =
 				rewriteTargetListIU(parsetree->targetList,
-									parsetree->commandType, rt_entry_relation,
+									parsetree->commandType,
+									parsetree->override,
+									rt_entry_relation,
 									parsetree->resultRelation, NULL);
 			rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
 		}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 5c823250bc..83838a4339 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5813,6 +5813,14 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (query->targetList)
 		appendStringInfoString(buf, ") ");
 
+	if (query->override)
+	{
+		if (query->override == OVERRIDING_SYSTEM_VALUE)
+			appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
+		else if (query->override == OVERRIDING_USER_VALUE)
+			appendStringInfoString(buf, "OVERRIDING USER VALUE ");
+	}
+
 	if (select_rte)
 	{
 		/* Add the SELECT */
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index b891f388e5..831a7f99a2 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -836,6 +836,27 @@ get_attnum(Oid relid, const char *attname)
 		return InvalidAttrNumber;
 }
 
+char
+get_attidentity(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		char			result;
+
+		result = att_tup->attidentity;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return 0;
+}
+
 /*
  * get_atttype
  *
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index ce55fc5277..778d80e3a2 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -3267,6 +3267,7 @@ RelationBuildLocalRelation(const char *relname,
 	has_not_null = false;
 	for (i = 0; i < natts; i++)
 	{
+		rel->rd_att->attrs[i]->attidentity = tupDesc->attrs[i]->attidentity;
 		rel->rd_att->attrs[i]->attnotnull = tupDesc->attrs[i]->attnotnull;
 		has_not_null |= tupDesc->attrs[i]->attnotnull;
 	}
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index b6e0e987a8..4f35471762 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -327,6 +327,7 @@ Section: Class 42 - Syntax Error or Access Rule Violation
 42P21    E    ERRCODE_COLLATION_MISMATCH                                     collation_mismatch
 42P22    E    ERRCODE_INDETERMINATE_COLLATION                                indeterminate_collation
 42809    E    ERRCODE_WRONG_OBJECT_TYPE                                      wrong_object_type
+428C9    E    ERRCODE_GENERATED_ALWAYS                                       generated_always
 
 # Note: for ERRCODE purposes, we divide namable objects into these categories:
 # databases, schemas, prepared statements, cursors, tables, columns,
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index e67171dccb..df7d0d8887 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -43,6 +43,7 @@
 #include "access/sysattr.h"
 #include "access/transam.h"
 #include "catalog/pg_am.h"
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_cast.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_default_acl.h"
@@ -1900,6 +1901,9 @@ dumpTableData_insert(Archive *fout, void *dcontext)
 						appendPQExpBufferStr(insertStmt, ") ");
 					}
 
+					if (tbinfo->needs_override)
+						appendPQExpBufferStr(insertStmt, "OVERRIDING SYSTEM VALUE ");
+
 					appendPQExpBufferStr(insertStmt, "VALUES (");
 				}
 			}
@@ -5422,6 +5426,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_toastreloptions;
 	int			i_reloftype;
 	int			i_relpages;
+	int			i_is_identity_sequence;
 	int			i_changed_acl;
 
 	/* Make sure we are in proper schema */
@@ -5499,6 +5504,7 @@ getTables(Archive *fout, int *numTables)
 						  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 						  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "
 						  "tc.reloptions AS toast_reloptions, "
+						  "c.relkind = '%c' AND EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND objsubid = 0 AND refclassid = 'pg_class'::regclass AND deptype = 'i') AS is_identity_sequence, "
 						  "EXISTS (SELECT 1 FROM pg_attribute at LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
 						  "AND pip.classoid = 'pg_class'::regclass "
@@ -5515,7 +5521,7 @@ getTables(Archive *fout, int *numTables)
 						  "(c.relkind = '%c' AND "
 						  "d.classid = c.tableoid AND d.objid = c.oid AND "
 						  "d.objsubid = 0 AND "
-						  "d.refclassid = c.tableoid AND d.deptype = 'a') "
+						  "d.refclassid = c.tableoid AND d.deptype IN ('a', 'i')) "
 					   "LEFT JOIN pg_class tc ON (c.reltoastrelid = tc.oid) "
 						  "LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
@@ -5528,6 +5534,7 @@ getTables(Archive *fout, int *numTables)
 						  initacl_subquery->data,
 						  initracl_subquery->data,
 						  username_subquery,
+						  RELKIND_SEQUENCE,
 						  attacl_subquery->data,
 						  attracl_subquery->data,
 						  attinitacl_subquery->data,
@@ -5950,6 +5957,7 @@ getTables(Archive *fout, int *numTables)
 	i_checkoption = PQfnumber(res, "checkoption");
 	i_toastreloptions = PQfnumber(res, "toast_reloptions");
 	i_reloftype = PQfnumber(res, "reloftype");
+	i_is_identity_sequence = PQfnumber(res, "is_identity_sequence");
 	i_changed_acl = PQfnumber(res, "changed_acl");
 
 	if (dopt->lockWaitTimeout)
@@ -6050,6 +6058,8 @@ getTables(Archive *fout, int *numTables)
 		tblinfo[i].dummy_view = false;	/* might get set during sort */
 		tblinfo[i].postponed_def = false;		/* might get set during sort */
 
+		tblinfo[i].is_identity_sequence = (strcmp(PQgetvalue(res, i, i_is_identity_sequence), "t") == 0);
+
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
 		 * in schema before we get around to dumping them.
@@ -7613,6 +7623,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	int			i_typstorage;
 	int			i_attnotnull;
 	int			i_atthasdef;
+	int			i_attidentity;
 	int			i_attisdropped;
 	int			i_attlen;
 	int			i_attalign;
@@ -7655,7 +7666,34 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 
 		resetPQExpBuffer(q);
 
-		if (fout->remoteVersion >= 90200)
+		if (fout->remoteVersion >= 100000)
+		{
+			/*
+			 * attidentity is new in version 10.
+			 */
+			appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
+							  "a.attstattarget, a.attstorage, t.typstorage, "
+							  "a.attnotnull, a.atthasdef, a.attisdropped, "
+							  "a.attlen, a.attalign, a.attislocal, "
+				  "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname, "
+						"array_to_string(a.attoptions, ', ') AS attoptions, "
+							  "CASE WHEN a.attcollation <> t.typcollation "
+						   "THEN a.attcollation ELSE 0 END AS attcollation, "
+							  "a.attidentity, "
+							  "pg_catalog.array_to_string(ARRAY("
+							  "SELECT pg_catalog.quote_ident(option_name) || "
+							  "' ' || pg_catalog.quote_literal(option_value) "
+						"FROM pg_catalog.pg_options_to_table(attfdwoptions) "
+							  "ORDER BY option_name"
+							  "), E',\n    ') AS attfdwoptions "
+			 "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
+							  "ON a.atttypid = t.oid "
+							  "WHERE a.attrelid = '%u'::pg_catalog.oid "
+							  "AND a.attnum > 0::pg_catalog.int2 "
+							  "ORDER BY a.attrelid, a.attnum",
+							  tbinfo->dobj.catId.oid);
+		}
+		else if (fout->remoteVersion >= 90200)
 		{
 			/*
 			 * attfdwoptions is new in 9.2.
@@ -7754,6 +7792,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		i_typstorage = PQfnumber(res, "typstorage");
 		i_attnotnull = PQfnumber(res, "attnotnull");
 		i_atthasdef = PQfnumber(res, "atthasdef");
+		i_attidentity = PQfnumber(res, "attidentity");
 		i_attisdropped = PQfnumber(res, "attisdropped");
 		i_attlen = PQfnumber(res, "attlen");
 		i_attalign = PQfnumber(res, "attalign");
@@ -7769,6 +7808,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		tbinfo->attstattarget = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attstorage = (char *) pg_malloc(ntups * sizeof(char));
 		tbinfo->typstorage = (char *) pg_malloc(ntups * sizeof(char));
+		tbinfo->attidentity = (char *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attisdropped = (bool *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attlen = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attalign = (char *) pg_malloc(ntups * sizeof(char));
@@ -7793,6 +7833,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, j, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
+			tbinfo->attidentity[j] = *(PQgetvalue(res, j, i_attidentity));
+			tbinfo->needs_override = tbinfo->needs_override || (tbinfo->attidentity[j] == ATTRIBUTE_IDENTITY_ALWAYS);
 			tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
 			tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
 			tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
@@ -16069,10 +16111,13 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
-					  fmtId(tbinfo->dobj.namespace->dobj.name));
-	appendPQExpBuffer(delqry, "%s;\n",
-					  fmtId(tbinfo->dobj.name));
+	if (!tbinfo->is_identity_sequence)
+	{
+		appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+		appendPQExpBuffer(delqry, "%s;\n",
+						  fmtId(tbinfo->dobj.name));
+	}
 
 	resetPQExpBuffer(query);
 
@@ -16084,11 +16129,30 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 												tbinfo->dobj.catId.oid);
 	}
 
-	appendPQExpBuffer(query,
-					  "CREATE SEQUENCE %s\n",
-					  fmtId(tbinfo->dobj.name));
+	if (tbinfo->is_identity_sequence)
+	{
+		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+
+		appendPQExpBuffer(query,
+						  "ALTER TABLE %s ",
+						  fmtId(owning_tab->dobj.name));
+		appendPQExpBuffer(query,
+						  "ALTER COLUMN %s ADD GENERATED ",
+						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
+		if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_ALWAYS)
+			appendPQExpBuffer(query, "ALWAYS");
+		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
+			appendPQExpBuffer(query, "BY DEFAULT");
+		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+						  fmtId(tbinfo->dobj.name));
+	}
+	else
+		appendPQExpBuffer(query,
+						  "CREATE SEQUENCE %s\n",
+						  fmtId(tbinfo->dobj.name));
 
-	if (strcmp(seqtype, "bigint") != 0)
+	if (strcmp(seqtype, "bigint") != 0 &&
+		!tbinfo->is_identity_sequence)
 		appendPQExpBuffer(query, "    AS %s\n", seqtype);
 
 	if (fout->remoteVersion >= 80400)
@@ -16110,7 +16174,10 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "    CACHE %s%s",
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
-	appendPQExpBufferStr(query, ";\n");
+	if (tbinfo->is_identity_sequence)
+		appendPQExpBufferStr(query, "\n);\n");
+	else
+		appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
@@ -16143,7 +16210,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	 * We need not schema-qualify the table reference because both sequence
 	 * and table must be in the same schema.
 	 */
-	if (OidIsValid(tbinfo->owning_tab))
+	if (OidIsValid(tbinfo->owning_tab) && !tbinfo->is_identity_sequence)
 	{
 		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
 
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index a466527ec6..f5ea2f7a6f 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -287,6 +287,7 @@ typedef struct _tableInfo
 	/* these two are set only if table is a sequence owned by a column: */
 	Oid			owning_tab;		/* OID of table owning sequence */
 	int			owning_col;		/* attr # of column owning sequence */
+	bool		is_identity_sequence;
 	int			relpages;		/* table's size in pages (from pg_class) */
 
 	bool		interesting;	/* true if need to collect more data */
@@ -305,6 +306,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	char	   *attidentity;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
 	char	   *attalign;		/* attribute align, used by binary_upgrade */
 	bool	   *attislocal;		/* true if attr has local definition */
@@ -316,6 +318,7 @@ typedef struct _tableInfo
 	struct _attrDefInfo **attrdefs;		/* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
 	char	   *partkeydef;		/* partition key definition */
+	bool		needs_override;	/* has GENERATED ALWAYS AS IDENTITY */
 
 	/*
 	 * Stuff computed only for dumpable tables.
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 61a3e2a848..085954732d 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -14,6 +14,7 @@
 
 #include <ctype.h>
 
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_default_acl.h"
 #include "fe_utils/string_utils.h"
@@ -1590,6 +1591,10 @@ describeOneTableDetails(const char *schemaname,
 							 "   WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation");
 	else
 		appendPQExpBufferStr(&buf, "\n  NULL AS attcollation");
+	if (pset.sversion >= 100000)
+		appendPQExpBufferStr(&buf, ", a.attidentity");
+	else
+		appendPQExpBufferStr(&buf, ", NULL AS attidentity");
 	if (tableinfo.relkind == RELKIND_INDEX)
 		appendPQExpBufferStr(&buf, ",\n  pg_catalog.pg_get_indexdef(a.attrelid, a.attnum, TRUE) AS indexdef");
 	else
@@ -1776,12 +1781,24 @@ describeOneTableDetails(const char *schemaname,
 		/* Collation, Nullable, Default */
 		if (show_column_details)
 		{
+			char   *identity;
+			char   *default_str = "";
+
 			printTableAddCell(&cont, PQgetvalue(res, i, 5), false, false);
 
 			printTableAddCell(&cont, strcmp(PQgetvalue(res, i, 3), "t") == 0 ? "not null" : "", false, false);
 
-			/* (note: above we cut off the 'default' string at 128) */
-			printTableAddCell(&cont, PQgetvalue(res, i, 2), false, false);
+			identity = PQgetvalue(res, i, 6);
+
+			if (identity[0] == ATTRIBUTE_IDENTITY_NONE)
+				/* (note: above we cut off the 'default' string at 128) */
+				default_str = PQgetvalue(res, i, 2);
+			else if (identity[0] == ATTRIBUTE_IDENTITY_ALWAYS)
+				default_str = "generated always as identity";
+			else if (identity[0] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
+				default_str = "generated by default as identity";
+
+			printTableAddCell(&cont, default_str, false, false);
 		}
 
 		/* Value: for sequences only */
@@ -1790,16 +1807,16 @@ describeOneTableDetails(const char *schemaname,
 
 		/* Expression for index column */
 		if (tableinfo.relkind == RELKIND_INDEX)
-			printTableAddCell(&cont, PQgetvalue(res, i, 6), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
 
 		/* FDW options for foreign table column, only for 9.2 or later */
 		if (tableinfo.relkind == RELKIND_FOREIGN_TABLE && pset.sversion >= 90200)
-			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 8), false, false);
 
 		/* Storage and Description */
 		if (verbose)
 		{
-			int			firstvcol = 8;
+			int			firstvcol = 9;
 			char	   *storage = PQgetvalue(res, i, firstvcol);
 
 			/* these strings are literal in our syntax, so not translated. */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index f7494065de..6ad9dc9df8 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1895,7 +1895,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> */
 	else if (Matches6("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny) ||
 			 Matches5("ALTER", "TABLE", MatchAny, "ALTER", MatchAny))
-		COMPLETE_WITH_LIST4("TYPE", "SET", "RESET", "DROP");
+		COMPLETE_WITH_LIST5("TYPE", "SET", "RESET", "ADD", "DROP");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
@@ -1911,7 +1911,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> DROP */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "DROP") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "DROP"))
-		COMPLETE_WITH_LIST2("DEFAULT", "NOT NULL");
+		COMPLETE_WITH_LIST3("DEFAULT", "IDENTITY", "NOT NULL");
 	else if (Matches4("ALTER", "TABLE", MatchAny, "CLUSTER"))
 		COMPLETE_WITH_CONST("ON");
 	else if (Matches5("ALTER", "TABLE", MatchAny, "CLUSTER", "ON"))
@@ -2920,17 +2920,25 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * Complete INSERT INTO <table> with "(" or "VALUES" or "SELECT" or
-	 * "TABLE" or "DEFAULT VALUES"
+	 * "TABLE" or "DEFAULT VALUES" or "OVERRIDING"
 	 */
 	else if (TailMatches3("INSERT", "INTO", MatchAny))
-		COMPLETE_WITH_LIST5("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES");
+		COMPLETE_WITH_LIST6("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES", "OVERRIDING");
 
 	/*
 	 * Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" or
-	 * "TABLE"
+	 * "TABLE" or "OVERRIDING"
 	 */
 	else if (TailMatches4("INSERT", "INTO", MatchAny, MatchAny) &&
 			 ends_with(prev_wd, ')'))
+		COMPLETE_WITH_LIST4("SELECT", "TABLE", "VALUES", "OVERRIDING");
+
+	/* Complete OVERRIDING */
+	else if (TailMatches1("OVERRIDING"))
+		COMPLETE_WITH_LIST2("SYSTEM VALUE", "USER VALUE");
+
+	/* Complete after OVERRIDING clause */
+	else if (TailMatches3("OVERRIDING", MatchAny, "VALUE"))
 		COMPLETE_WITH_LIST3("SELECT", "TABLE", "VALUES");
 
 	/* Insert an open parenthesis after "VALUES" */
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 10759c7c58..c5044b4af9 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -237,11 +237,9 @@ extern long changeDependencyFor(Oid classId, Oid objectId,
 
 extern Oid	getExtensionOfObject(Oid classId, Oid objectId);
 
-extern bool sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId);
-
-extern void markSequenceUnowned(Oid seqId);
-
-extern List *getOwnedSequences(Oid relid);
+extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId);
+extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
+extern Oid getOwnedSequence(Oid relid, AttrNumber attnum);
 
 extern Oid	get_constraint_index(Oid constraintId);
 
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index e861f4c589..0deb5c86c8 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -133,6 +133,9 @@ CATALOG(pg_attribute,1249) BKI_BOOTSTRAP BKI_WITHOUT_OIDS BKI_ROWTYPE_OID(75) BK
 	/* Has DEFAULT value or not */
 	bool		atthasdef;
 
+	/* One of the ATTRIBUTE_IDENTITY_* constants below */
+	char		attidentity;
+
 	/* Is dropped (ie, logically invisible) or not */
 	bool		attisdropped;
 
@@ -188,7 +191,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
-#define Natts_pg_attribute				21
+#define Natts_pg_attribute				22
 #define Anum_pg_attribute_attrelid		1
 #define Anum_pg_attribute_attname		2
 #define Anum_pg_attribute_atttypid		3
@@ -203,13 +206,14 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 #define Anum_pg_attribute_attalign		12
 #define Anum_pg_attribute_attnotnull	13
 #define Anum_pg_attribute_atthasdef		14
-#define Anum_pg_attribute_attisdropped	15
-#define Anum_pg_attribute_attislocal	16
-#define Anum_pg_attribute_attinhcount	17
-#define Anum_pg_attribute_attcollation	18
-#define Anum_pg_attribute_attacl		19
-#define Anum_pg_attribute_attoptions	20
-#define Anum_pg_attribute_attfdwoptions 21
+#define Anum_pg_attribute_attidentity	15
+#define Anum_pg_attribute_attisdropped	16
+#define Anum_pg_attribute_attislocal	17
+#define Anum_pg_attribute_attinhcount	18
+#define Anum_pg_attribute_attcollation	19
+#define Anum_pg_attribute_attacl		20
+#define Anum_pg_attribute_attoptions	21
+#define Anum_pg_attribute_attfdwoptions 22
 
 
 /* ----------------
@@ -220,4 +224,9 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
+
+#define		  ATTRIBUTE_IDENTITY_NONE		' '
+#define		  ATTRIBUTE_IDENTITY_ALWAYS		'a'
+#define		  ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
+
 #endif   /* PG_ATTRIBUTE_H */
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index d1d493ee05..5a288830e8 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -149,7 +149,7 @@ typedef FormData_pg_class *Form_pg_class;
  */
 DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 21 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
 DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 29 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 49a77c42fc..304586e48e 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -51,7 +51,9 @@ typedef struct xl_seq_rec
 	/* SEQUENCE TUPLE DATA FOLLOWS AT THE END */
 } xl_seq_rec;
 
+extern int64 nextval_internal(Oid relid, bool check_permissions);
 extern Datum nextval(PG_FUNCTION_ARGS);
+extern List *sequence_options(Oid relid);
 
 extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
 extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 2bc7a5df11..1da74e148e 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -188,6 +188,7 @@ typedef enum NodeTag
 	T_FromExpr,
 	T_OnConflictExpr,
 	T_IntoClause,
+	T_NextValueExpr,
 
 	/*
 	 * TAGS FOR EXPRESSION STATE NODES (execnodes.h)
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index a15df229a4..2d5a5074c0 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -27,6 +27,13 @@
 #include "nodes/primnodes.h"
 #include "nodes/value.h"
 
+typedef enum OverridingKind
+{
+	OVERRIDING_NOT_SET = 0,
+	OVERRIDING_USER_VALUE,
+	OVERRIDING_SYSTEM_VALUE
+} OverridingKind;
+
 /* Possible sources of a Query */
 typedef enum QuerySource
 {
@@ -130,6 +137,8 @@ typedef struct Query
 
 	List	   *targetList;		/* target list (of TargetEntry) */
 
+	OverridingKind override;	/* OVERRIDING clause */
+
 	OnConflictExpr *onConflict; /* ON CONFLICT DO [NOTHING | UPDATE] */
 
 	List	   *returningList;	/* return-values list (of TargetEntry) */
@@ -637,6 +646,7 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	char		identity;		/* attidentity setting */
 	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
@@ -658,9 +668,10 @@ typedef enum TableLikeOption
 {
 	CREATE_TABLE_LIKE_DEFAULTS = 1 << 0,
 	CREATE_TABLE_LIKE_CONSTRAINTS = 1 << 1,
-	CREATE_TABLE_LIKE_INDEXES = 1 << 2,
-	CREATE_TABLE_LIKE_STORAGE = 1 << 3,
-	CREATE_TABLE_LIKE_COMMENTS = 1 << 4,
+	CREATE_TABLE_LIKE_IDENTITY = 1 << 2,
+	CREATE_TABLE_LIKE_INDEXES = 1 << 3,
+	CREATE_TABLE_LIKE_STORAGE = 1 << 4,
+	CREATE_TABLE_LIKE_COMMENTS = 1 << 5,
 	CREATE_TABLE_LIKE_ALL = PG_INT32_MAX
 } TableLikeOption;
 
@@ -1399,6 +1410,7 @@ typedef struct InsertStmt
 	OnConflictClause *onConflictClause; /* ON CONFLICT clause */
 	List	   *returningList;	/* list of expressions to return */
 	WithClause *withClause;		/* WITH clause */
+	OverridingKind override;	/* OVERRIDING clause */
 } InsertStmt;
 
 /* ----------------------
@@ -1708,7 +1720,10 @@ typedef enum AlterTableType
 	AT_NoForceRowSecurity,		/* NO FORCE ROW SECURITY */
 	AT_GenericOptions,			/* OPTIONS (...) */
 	AT_AttachPartition,			/* ATTACH PARTITION */
-	AT_DetachPartition			/* DETACH PARTITION */
+	AT_DetachPartition,			/* DETACH PARTITION */
+	AT_AddIdentity,				/* ADD IDENTITY */
+	AT_SetIdentity,				/* SET identity column options */
+	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
@@ -1984,6 +1999,7 @@ typedef enum ConstrType			/* types of constraints */
 								 * expect it */
 	CONSTR_NOTNULL,
 	CONSTR_DEFAULT,
+	CONSTR_IDENTITY,
 	CONSTR_CHECK,
 	CONSTR_PRIMARY,
 	CONSTR_UNIQUE,
@@ -2022,6 +2038,7 @@ typedef struct Constraint
 	bool		is_no_inherit;	/* is constraint non-inheritable? */
 	Node	   *raw_expr;		/* expr, as untransformed parse tree */
 	char	   *cooked_expr;	/* expr, as nodeToString representation */
+	char		generated_when;
 
 	/* Fields used for unique constraints (UNIQUE and PRIMARY KEY): */
 	List	   *keys;			/* String nodes naming referenced column(s) */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index d57b4fab3d..b87fe84545 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1292,6 +1292,20 @@ typedef struct InferenceElem
 	Oid			inferopclass;	/* OID of att opclass, or InvalidOid */
 } InferenceElem;
 
+/*
+ * NextValueExpr - get next value from sequence
+ *
+ * This has the same effect as calling the nextval() function, but it does not
+ * check permissions on the sequence.  This is used for identity columns,
+ * where the sequence is an implicit dependency without its own permissions.
+ */
+typedef struct NextValueExpr
+{
+	Expr		xpr;
+	Oid			seqid;
+	Oid			typeId;
+} NextValueExpr;
+
 /*--------------------
  * TargetEntry -
  *	   a target entry (used in query target lists)
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 28c4dab258..086420871b 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -174,6 +174,7 @@ PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
 PG_KEYWORD("full", FULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("function", FUNCTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("functions", FUNCTIONS, UNRESERVED_KEYWORD)
+PG_KEYWORD("generated", GENERATED, UNRESERVED_KEYWORD)
 PG_KEYWORD("global", GLOBAL, UNRESERVED_KEYWORD)
 PG_KEYWORD("grant", GRANT, RESERVED_KEYWORD)
 PG_KEYWORD("granted", GRANTED, UNRESERVED_KEYWORD)
@@ -286,6 +287,7 @@ PG_KEYWORD("outer", OUTER_P, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("over", OVER, UNRESERVED_KEYWORD)
 PG_KEYWORD("overlaps", OVERLAPS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("overlay", OVERLAY, COL_NAME_KEYWORD)
+PG_KEYWORD("overriding", OVERRIDING, UNRESERVED_KEYWORD)
 PG_KEYWORD("owned", OWNED, UNRESERVED_KEYWORD)
 PG_KEYWORD("owner", OWNER, UNRESERVED_KEYWORD)
 PG_KEYWORD("parallel", PARALLEL, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index b6d1fca2fa..88629d99aa 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -64,6 +64,7 @@ extern Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 extern char *get_attname(Oid relid, AttrNumber attnum);
 extern char *get_relid_attribute_name(Oid relid, AttrNumber attnum);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
+extern char	get_attidentity(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index a25b221703..3f405c94ce 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -66,6 +66,53 @@ SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y
 (2 rows)
 
 DROP TABLE inhg;
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+                     Table "public.test_like_id_1"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+ a | b  
+---+----
+ 1 | b1
+(1 row)
+
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+           Table "public.test_like_id_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           | not null | 
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, b2).
+SELECT * FROM test_like_id_2;  -- identity was not copied
+ a | b 
+---+---
+(0 rows)
+
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+                     Table "public.test_like_id_3"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+ a | b  
+---+----
+ 1 | b3
+(1 row)
+
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
new file mode 100644
index 0000000000..7df46cf71f
--- /dev/null
+++ b/src/test/regress/expected/identity.out
@@ -0,0 +1,314 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest3" is already an identity column
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+ table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
+------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
+ itest1     | a           |                | NO          | YES         | BY DEFAULT          | 1              | 1                  | 2147483647          | 1                | NO
+ itest1     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest2     | a           |                | NO          | YES         | ALWAYS              | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest2     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest3     | a           |                | NO          | YES         | BY DEFAULT          | 7              | 5                  | 32767               | 1                | NO
+ itest3     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+(6 rows)
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+ sequence_name 
+---------------
+(0 rows)
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ERROR:  column "a" of relation "itest4" is an identity column
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ERROR:  column "a" of relation "itest4" is already an identity column
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ERROR:  identity column type must be smallint, integer, or bigint
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+ERROR:  identity column type must be smallint, integer, or bigint
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+ERROR:  multiple identity specifications for column "a" of table "itest_err_2"
+LINE 1: ...E itest_err_2 (a int generated always as identity generated ...
+                                                             ^
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_3"
+LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau...
+                                                  ^
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_4"
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest1;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest2;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest3;
+ a  | b 
+----+---
+  7 | 
+ 12 | 
+(2 rows)
+
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+-- OVERRIDING tests
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+SELECT * FROM itest1;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+(3 rows)
+
+-- UPDATE tests
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+  a  |  b  
+-----+-----
+  10 | xyz
+   3 | xyz
+ 101 | 
+   4 | 
+(4 rows)
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+ERROR:  column "a" can only be updated to DEFAULT
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+ 10 | xyz
+  3 | 
+(3 rows)
+
+-- DROP IDENTITY tests
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is not an identity column
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, ).
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+   | 
+(3 rows)
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+ERROR:  relation "itest4_a_seq" does not exist
+LINE 1: SELECT sequence_name FROM itest4_a_seq;
+                                  ^
+-- test views
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+SELECT * FROM itestv10;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itestv11;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv10;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv11;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 11 | xyz
+(3 rows)
+
+-- various ALTER COLUMN tests
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+ERROR:  column "a" of relation "itest1" is an identity column
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ERROR:  column "a" of relation "itest5" already has a default value
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+ seqtypid 
+----------
+ integer
+(1 row)
+
+\d itest3
+                           Table "public.itest3"
+ Column |  Type   | Collation | Nullable |             Default              
+--------+---------+-----------+----------+----------------------------------
+ a      | integer |           | not null | generated by default as identity
+ b      | text    |           |          | 
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+ERROR:  identity column type must be smallint, integer, or bigint
+-- ALTER COLUMN ... SET
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+  a  | b 
+-----+---
+   1 | 
+ 100 | 
+ 102 | 
+(3 rows)
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+ table_name | column_name | is_identity | identity_generation 
+------------+-------------+-------------+---------------------
+ itest6     | a           | YES         | BY DEFAULT
+ itest6     | b           | NO          | 
+(2 rows)
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+ERROR:  column "b" of relation "itest6" is not an identity column
+-- prohibited direct modification of sequence
+ALTER SEQUENCE itest6_a_seq OWNED BY NONE;
+ERROR:  cannot change ownership of identity sequence
+DETAIL:  Sequence "itest6_a_seq" is linked to table "itest6".
+-- inheritance
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+(1 row)
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+NOTICE:  merging column "a" with inherited definition
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+ a 
+---
+ 1
+(1 row)
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  cannot recursively add identity column to table that has child tables
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+ table_name | column_name | is_nullable | is_identity | identity_generation 
+------------+-------------+-------------+-------------+---------------------
+ itest7     | a           | NO          | YES         | ALWAYS
+ itest7a    | a           | NO          | NO          | 
+ itest7a    | b           | YES         | NO          | 
+ itest7b    | a           | YES         | NO          | 
+ itest7c    | a           | NO          | YES         | ALWAYS
+ itest7d    | a           | NO          | YES         | ALWAYS
+ itest7e    | a           | NO          | NO          | 
+(7 rows)
+
+-- These ALTER TABLE variants will not recurse.
+ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT;
+ALTER TABLE itest7 ALTER COLUMN a RESTART;
+ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY;
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+ a | b 
+---+---
+ 1 | 
+(1 row)
+
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/expected/sequence.out b/src/test/regress/expected/sequence.out
index f339489151..469c082ad1 100644
--- a/src/test/regress/expected/sequence.out
+++ b/src/test/regress/expected/sequence.out
@@ -20,8 +20,8 @@ ERROR:  CACHE (0) must be greater than zero
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
 ERROR:  invalid OWNED BY option
 HINT:  Specify OWNED BY table.column or OWNED BY NONE.
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
-ERROR:  referenced relation "pg_tables" is not a table or foreign table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
+ERROR:  referenced relation "pg_class_oid_index" is not a table or foreign table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 ERROR:  sequence must be in same schema as table it is linked to
 CREATE TABLE sequence_test_table (a int);
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index 81612d8c88..b652562f5b 100644
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -393,6 +393,36 @@ SELECT * FROM truncate_a;
   2 |  34
 (2 rows)
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
+TRUNCATE truncate_b;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 46
+ 47
+(2 rows)
+
+TRUNCATE truncate_b RESTART IDENTITY;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 38743d98c3..bfc17705ea 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -111,6 +111,11 @@ test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combo
 # ----------
 test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml
 
+# ----------
+# Another group of parallel tests
+# ----------
+test: identity
+
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger
 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index d9f64c2873..f451e3a422 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -169,6 +169,7 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
+test: identity
 test: polymorphism
 test: rowtypes
 test: returning
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 900ca804cb..557040bbe7 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -37,6 +37,20 @@ CREATE TABLE inhg (x text, LIKE inhx INCLUDING CONSTRAINTS, y text); /* Copies c
 SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y */
 DROP TABLE inhg;
 
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+SELECT * FROM test_like_id_2;  -- identity was not copied
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
+
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
new file mode 100644
index 0000000000..efcd2aa1cc
--- /dev/null
+++ b/src/test/regress/sql/identity.sql
@@ -0,0 +1,187 @@
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+
+SELECT * FROM itest1;
+SELECT * FROM itest2;
+SELECT * FROM itest3;
+SELECT * FROM itest4;
+
+
+-- OVERRIDING tests
+
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest1;
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest2;
+
+
+-- UPDATE tests
+
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+
+
+-- DROP IDENTITY tests
+
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+
+
+-- test views
+
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+
+SELECT * FROM itestv10;
+SELECT * FROM itestv11;
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv10;
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv11;
+
+
+-- various ALTER COLUMN tests
+
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+\d itest3
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+
+
+-- ALTER COLUMN ... SET
+
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+
+
+-- prohibited direct modification of sequence
+
+ALTER SEQUENCE itest6_a_seq OWNED BY NONE;
+
+
+-- inheritance
+
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+
+-- These ALTER TABLE variants will not recurse.
+ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT;
+ALTER TABLE itest7 ALTER COLUMN a RESTART;
+ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY;
+
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
index 0fbd255967..18fa6ae5e9 100644
--- a/src/test/regress/sql/sequence.sql
+++ b/src/test/regress/sql/sequence.sql
@@ -13,7 +13,7 @@ CREATE SEQUENCE sequence_testx CACHE 0;
 
 -- OWNED BY errors
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 CREATE TABLE sequence_test_table (a int);
 CREATE SEQUENCE sequence_testx OWNED BY sequence_test_table.b;  -- wrong column
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index d61eea1a42..9d3d8de54a 100644
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -202,6 +202,24 @@ CREATE TABLE truncate_a (id serial,
 INSERT INTO truncate_a DEFAULT VALUES;
 SELECT * FROM truncate_a;
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b RESTART IDENTITY;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
-- 
2.12.0

From 1b46020f06b39b9c3d3f5178bed517120f34f1a6 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 28 Feb 2017 21:09:02 -0500
Subject: [PATCH v6] Identity columns

This is the SQL standard-conforming variant of PostgreSQL's serial
columns.  It also fixes a few usability issues that serial columns
have:

- CREATE TABLE / LIKE copies default but refers to same sequence
- cannot add/drop serialness with ALTER TABLE
- dropping default does not drop sequence
- need to grant separate privileges to sequence
- slight weirdnesses because serial is some kind of special macro
---
 doc/src/sgml/catalogs.sgml                      |  11 +
 doc/src/sgml/information_schema.sgml            |  11 +-
 doc/src/sgml/ref/alter_table.sgml               |  42 ++-
 doc/src/sgml/ref/copy.sgml                      |   7 +
 doc/src/sgml/ref/create_table.sgml              |  65 ++++-
 doc/src/sgml/ref/insert.sgml                    |  41 +++
 src/backend/access/common/tupdesc.c             |   6 +
 src/backend/catalog/dependency.c                |   7 +
 src/backend/catalog/genbki.pl                   |   7 +-
 src/backend/catalog/heap.c                      |  15 +-
 src/backend/catalog/index.c                     |   1 +
 src/backend/catalog/information_schema.sql      |  17 +-
 src/backend/catalog/pg_depend.c                 |  52 ++--
 src/backend/catalog/sql_features.txt            |  12 +-
 src/backend/commands/sequence.c                 | 101 +++++--
 src/backend/commands/tablecmds.c                | 295 ++++++++++++++++++-
 src/backend/executor/execExpr.c                 |  11 +
 src/backend/executor/execExprInterp.c           |  10 +
 src/backend/nodes/copyfuncs.c                   |  23 ++
 src/backend/nodes/equalfuncs.c                  |  18 ++
 src/backend/nodes/nodeFuncs.c                   |  11 +
 src/backend/nodes/outfuncs.c                    |   9 +
 src/backend/nodes/readfuncs.c                   |   1 +
 src/backend/parser/analyze.c                    |   2 +
 src/backend/parser/gram.y                       | 133 ++++++++-
 src/backend/parser/parse_utilcmd.c              | 360 +++++++++++++++++++-----
 src/backend/rewrite/rewriteHandler.c            |  56 +++-
 src/backend/utils/adt/ruleutils.c               |   8 +
 src/backend/utils/cache/lsyscache.c             |  32 +++
 src/backend/utils/cache/relcache.c              |   1 +
 src/backend/utils/errcodes.txt                  |   1 +
 src/bin/pg_dump/pg_dump.c                       |  91 +++++-
 src/bin/pg_dump/pg_dump.h                       |   3 +
 src/bin/psql/describe.c                         |  27 +-
 src/bin/psql/tab-complete.c                     |  18 +-
 src/include/catalog/dependency.h                |   8 +-
 src/include/catalog/pg_attribute.h              |  24 +-
 src/include/catalog/pg_class.h                  |   2 +-
 src/include/commands/sequence.h                 |   2 +
 src/include/executor/execExpr.h                 |   7 +
 src/include/nodes/nodes.h                       |   1 +
 src/include/nodes/parsenodes.h                  |  27 +-
 src/include/nodes/primnodes.h                   |  14 +
 src/include/parser/kwlist.h                     |   2 +
 src/include/utils/lsyscache.h                   |   1 +
 src/test/regress/expected/create_table_like.out |  47 ++++
 src/test/regress/expected/identity.out          | 322 +++++++++++++++++++++
 src/test/regress/expected/sequence.out          |   4 +-
 src/test/regress/expected/truncate.out          |  30 ++
 src/test/regress/parallel_schedule              |   5 +
 src/test/regress/serial_schedule                |   1 +
 src/test/regress/sql/create_table_like.sql      |  14 +
 src/test/regress/sql/identity.sql               | 192 +++++++++++++
 src/test/regress/sql/sequence.sql               |   2 +-
 src/test/regress/sql/truncate.sql               |  18 ++
 55 files changed, 2030 insertions(+), 198 deletions(-)
 create mode 100644 src/test/regress/expected/identity.out
 create mode 100644 src/test/regress/sql/identity.sql

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index ac39c639ed..b352585bc0 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -1130,6 +1130,17 @@ <title><structname>pg_attribute</> Columns</title>
      </row>
 
      <row>
+      <entry><structfield>attidentity</structfield></entry>
+      <entry><type>char</type></entry>
+      <entry></entry>
+      <entry>
+       If a zero byte (<literal>''</literal>), then not an identity column.
+       Otherwise, <literal>a</literal> = generated
+       always, <literal>d</literal> = generated by default.
+      </entry>
+     </row>
+
+     <row>
       <entry><structfield>attisdropped</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index a3a19ce8ce..02f7927436 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -1583,13 +1583,20 @@ <title><literal>columns</literal> Columns</title>
      <row>
       <entry><literal>is_identity</literal></entry>
       <entry><type>yes_or_no</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>YES</literal>,
+       else <literal>NO</literal>.
+      </entry>
      </row>
 
      <row>
       <entry><literal>identity_generation</literal></entry>
       <entry><type>character_data</type></entry>
-      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
+      <entry>
+       If the column is an identity column, then <literal>ALWAYS</literal>
+       or <literal>BY DEFAULT</literal>, reflecting the definition of the
+       column.
+      </entry>
      </row>
 
      <row>
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 7829f378bb..93b1ad17a3 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -46,6 +46,9 @@
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESTART [ [ WITH ] <replaceable class="parameter">restart</replaceable> ] } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY [ IF EXISTS ]
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> RESET ( <replaceable class="PARAMETER">attribute_option</replaceable> [, ... ] )
@@ -188,6 +191,38 @@ <title>Description</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
+    <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
+    <term><literal>DROP IDENTITY [ IF EXISTS ]</literal></term>
+    <listitem>
+     <para>
+      These forms change whether a column is an identity column or change the
+      generation attribute of an existing identity column.
+      See <xref linkend="sql-createtable"> for details.
+     </para>
+
+     <para>
+      If <literal>DROP IDENTITY IF EXISTS</literal> is specified and the
+      column is not an identity column, no error is thrown.  In this case a
+      notice is issued instead.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>SET <replaceable>sequence_option</replaceable></literal></term>
+    <term><literal>RESTART</literal></term>
+    <listitem>
+     <para>
+      These forms alter the sequence that underlies an existing identity
+      column.  <replaceable>sequence_option</replaceable> is an option
+      supported by <xref linkend="sql-altersequence"> such
+      as <literal>INCREMENT BY</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>SET STATISTICS</literal></term>
     <listitem>
      <para>
@@ -1160,8 +1195,11 @@ <title>Notes</title>
    </para>
 
    <para>
-    The <literal>TRIGGER</>, <literal>CLUSTER</>, <literal>OWNER</>,
-    and <literal>TABLESPACE</> actions never recurse to descendant tables;
+    The actions for identity columns (<literal>ADD
+    GENERATED</literal>, <literal>SET</literal> etc., <literal>DROP
+    IDENTITY</literal>), as well as the actions
+    <literal>TRIGGER</>, <literal>CLUSTER</>, <literal>OWNER</>,
+    and <literal>TABLESPACE</> never recurse to descendant tables;
     that is, they always act as though <literal>ONLY</> were specified.
     Adding a constraint recurses only for <literal>CHECK</> constraints
     that are not marked <literal>NO INHERIT</>.
diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index 7ff62f2a82..215efcd69d 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -480,6 +480,13 @@ <title>Notes</title>
    </para>
 
    <para>
+    For identity columns, the <command>COPY FROM</command> command will always
+    write the column values provided in the input data, like
+    the <command>INPUT</command> option <literal>OVERRIDING SYSTEM
+    VALUE</literal>.
+   </para>
+
+   <para>
     <command>COPY</command> input and output is affected by
     <varname>DateStyle</varname>. To ensure portability to other
     <productname>PostgreSQL</productname> installations that might use
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 283d53e203..809ad66bb9 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -62,6 +62,7 @@
   NULL |
   CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
   DEFAULT <replaceable>default_expr</replaceable> |
+  GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ] |
   UNIQUE <replaceable class="PARAMETER">index_parameters</replaceable> |
   PRIMARY KEY <replaceable class="PARAMETER">index_parameters</replaceable> |
   REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
@@ -81,7 +82,7 @@
 
 <phrase>and <replaceable class="PARAMETER">like_option</replaceable> is:</phrase>
 
-{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
+{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | IDENTITY | INDEXES | STORAGE | COMMENTS | ALL }
 
 <phrase>and <replaceable class="PARAMETER">partition_bound_spec</replaceable> is:</phrase>
 
@@ -412,6 +413,11 @@ <title>Parameters</title>
       Column <literal>STORAGE</> settings are also copied from parent tables.
      </para>
 
+     <para>
+      If a column in the parent table is an identity column, that property is
+      not inherited.  A column in the child table can be declared identity
+      column if desired.
+     </para>
     </listitem>
    </varlistentry>
 
@@ -481,6 +487,12 @@ <title>Parameters</title>
       the original and new tables.
      </para>
      <para>
+      Any identity specifications of copied column definitions will only be
+      copied if <literal>INCLUDING IDENTITY</literal> is specified.  A new
+      sequence is created for each identity column of the new table, separate
+      from the sequences associated with the old table.
+     </para>
+     <para>
       Not-null constraints are always copied to the new table.
       <literal>CHECK</literal> constraints will be copied only if
       <literal>INCLUDING CONSTRAINTS</literal> is specified.
@@ -512,7 +524,7 @@ <title>Parameters</title>
      </para>
      <para>
       <literal>INCLUDING ALL</literal> is an abbreviated form of
-      <literal>INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
+      <literal>INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING CONSTRAINTS INCLUDING INDEXES INCLUDING STORAGE INCLUDING COMMENTS</literal>.
      </para>
      <para>
       Note that unlike <literal>INHERITS</literal>, columns and
@@ -627,6 +639,37 @@ <title>Parameters</title>
    </varlistentry>
 
    <varlistentry>
+    <term><literal>GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]</literal></term>
+    <listitem>
+     <para>
+      This clause creates the column as an <firstterm>identity
+      column</firstterm>.  It will have an implicit sequence attached to it
+      and the column in new rows will automatically have values from the
+      sequence assigned to it.
+     </para>
+
+     <para>
+      The clauses <literal>ALWAYS</literal> and <literal>BY DEFAULT</literal>
+      determine how the sequence value is given precedence over a
+      user-specified value in an <command>INSERT</command> statement.
+      If <literal>ALWAYS</literal> is specified, a user-specified value is
+      only accepted if the <command>INSERT</command> statement
+      specifies <literal>OVERRIDING SYSTEM VALUE</literal>.  If <literal>BY
+      DEFAULT</literal> is specified, then the user-specified value takes
+      precedence.  See <xref linkend="sql-insert"> for details.  (In
+      the <command>COPY</command> command, user-specified values are always
+      used regardless of this setting.)
+     </para>
+
+     <para>
+      The optional <replaceable>sequence_options</replaceable> clause can be
+      used to override the options of the sequence.
+      See <xref linkend="sql-createsequence"> for details.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
     <term><literal>UNIQUE</> (column constraint)</term>
     <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
 
@@ -1259,7 +1302,7 @@ <title>Notes</title>
 
     <para>
      Using OIDs in new applications is not recommended: where
-     possible, using a <literal>SERIAL</literal> or other sequence
+     possible, using an identity column or other sequence
      generator as the table's primary key is preferred. However, if
      your application does make use of OIDs to identify specific
      rows of a table, it is recommended to create a unique constraint
@@ -1319,7 +1362,7 @@ <title>Examples</title>
 );
 
 CREATE TABLE distributors (
-     did    integer PRIMARY KEY DEFAULT nextval('serial'),
+     did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
      name   varchar(40) NOT NULL CHECK (name &lt;&gt; '')
 );
 </programlisting>
@@ -1734,6 +1777,20 @@ <title>Zero-column Tables</title>
   </refsect2>
 
   <refsect2>
+   <title>Multiple Identity Columns</title>
+
+   <para>
+    <productname>PostgreSQL</productname> allows a table to have more than one
+    identity column.  The standard specifies that a table can have at most one
+    identity column.  This is relaxed mainly to give more flexibility for
+    doing schema changes or migrations.  Note that
+    the <command>INSERT</command> command supports only one override clause
+    that applies to the entire statement, so having multiple identity columns
+    with different behaviors is not well supported.
+   </para>
+  </refsect2>
+
+  <refsect2>
    <title><literal>LIKE</> Clause</title>
 
    <para>
diff --git a/doc/src/sgml/ref/insert.sgml b/doc/src/sgml/ref/insert.sgml
index 521216b5d5..95aa77b907 100644
--- a/doc/src/sgml/ref/insert.sgml
+++ b/doc/src/sgml/ref/insert.sgml
@@ -23,6 +23,7 @@
 <synopsis>
 [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ]
 INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replaceable class="parameter">alias</replaceable> ] [ ( <replaceable class="PARAMETER">column_name</replaceable> [, ...] ) ]
+    [ OVERRIDING { SYSTEM | USER} VALUE ]
     { DEFAULT VALUES | VALUES ( { <replaceable class="PARAMETER">expression</replaceable> | DEFAULT } [, ...] ) [, ...] | <replaceable class="PARAMETER">query</replaceable> }
     [ ON CONFLICT [ <replaceable class="parameter">conflict_target</replaceable> ] <replaceable class="parameter">conflict_action</replaceable> ]
     [ RETURNING * | <replaceable class="parameter">output_expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ]
@@ -202,10 +203,43 @@ <title id="sql-inserting-params-title">Inserting</title>
      </varlistentry>
 
      <varlistentry>
+      <term><literal>OVERRIDING SYSTEM VALUE</literal></term>
+      <listitem>
+       <para>
+        Without this clause, it is an error to specify an explicit value
+        (other than <literal>DEFAULT</literal>) for an identity column defined
+        as <literal>GENERATED ALWAYS</literal>.  This clause overrides that
+        restriction.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><literal>OVERRIDING USER VALUE</literal></term>
+      <listitem>
+       <para>
+        If this clause is specified, then any values supplied for identity
+        columns defined as <literal>GENERATED BY DEFAULT</literal> are ignored
+        and the default sequence-generated values are applied.
+       </para>
+
+       <para>
+        This clause is useful for example when copying values between tables.
+        Writing <literal>INSERT INTO tbl2 OVERRIDING USER VALUE SELECT * FROM
+        tbl1</literal> will copy from <literal>tbl1</literal> all columns that
+        are not identity columns in <literal>tbl2</literal> but will continue
+        the sequence counters for any identity columns.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><literal>DEFAULT VALUES</literal></term>
       <listitem>
        <para>
         All columns will be filled with their default values.
+        (An <literal>OVERRIDING</literal> clause is not permitted in this
+        form.)
        </para>
       </listitem>
      </varlistentry>
@@ -711,6 +745,13 @@ <title>Compatibility</title>
   </para>
 
   <para>
+   The SQL standard specifies that <literal>OVERRIDING SYSTEM VALUE</literal>
+   can only be specified if an identity column that is generated always
+   exists.  PostgreSQL allows the clause in any case and ignores it if it is
+   not applicable.
+  </para>
+
+  <para>
    Possible limitations of the <replaceable
    class="PARAMETER">query</replaceable> clause are documented under
    <xref linkend="sql-select">.
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index 4e2ebe1ae7..9fd7b4e019 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -150,6 +150,7 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
 		desc->attrs[i]->attnotnull = false;
 		desc->attrs[i]->atthasdef = false;
+		desc->attrs[i]->attidentity = '\0';
 	}
 
 	desc->tdtypeid = tupdesc->tdtypeid;
@@ -257,6 +258,7 @@ TupleDescCopyEntry(TupleDesc dst, AttrNumber dstAttno,
 	/* since we're not copying constraints or defaults, clear these */
 	dst->attrs[dstAttno - 1]->attnotnull = false;
 	dst->attrs[dstAttno - 1]->atthasdef = false;
+	dst->attrs[dstAttno - 1]->attidentity = '\0';
 }
 
 /*
@@ -401,6 +403,8 @@ equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
 			return false;
 		if (attr1->atthasdef != attr2->atthasdef)
 			return false;
+		if (attr1->attidentity != attr2->attidentity)
+			return false;
 		if (attr1->attisdropped != attr2->attisdropped)
 			return false;
 		if (attr1->attislocal != attr2->attislocal)
@@ -534,6 +538,7 @@ TupleDescInitEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = '\0';
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
@@ -591,6 +596,7 @@ TupleDescInitBuiltinEntry(TupleDesc desc,
 
 	att->attnotnull = false;
 	att->atthasdef = false;
+	att->attidentity = '\0';
 	att->attisdropped = false;
 	att->attislocal = true;
 	att->attinhcount = 0;
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index ee27cae7df..cdf453562f 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -1929,6 +1929,13 @@ find_expr_references_walker(Node *node,
 						   context->addrs);
 		/* fall through to examine arguments */
 	}
+	else if (IsA(node, NextValueExpr))
+	{
+		NextValueExpr  *nve = (NextValueExpr *) node;
+
+		add_object_address(OCLASS_CLASS, nve->seqid, 0,
+						   context->addrs);
+	}
 
 	return expression_tree_walker(node, find_expr_references_walker,
 								  (void *) context);
diff --git a/src/backend/catalog/genbki.pl b/src/backend/catalog/genbki.pl
index f9ecb02548..6e9d57aa8d 100644
--- a/src/backend/catalog/genbki.pl
+++ b/src/backend/catalog/genbki.pl
@@ -409,6 +409,7 @@ sub emit_pgattr_row
 		attcacheoff   => '-1',
 		atttypmod     => '-1',
 		atthasdef     => 'f',
+		attidentity   => '',
 		attisdropped  => 'f',
 		attislocal    => 't',
 		attinhcount   => '0',
@@ -424,7 +425,7 @@ sub bki_insert
 	my $row        = shift;
 	my @attnames   = @_;
 	my $oid        = $row->{oid} ? "OID = $row->{oid} " : '';
-	my $bki_values = join ' ', map $row->{$_}, @attnames;
+	my $bki_values = join ' ', map { $_ eq '' ? '""' : $_ } map $row->{$_}, @attnames;
 	printf $bki "insert %s( %s)\n", $oid, $bki_values;
 }
 
@@ -435,10 +436,14 @@ sub emit_schemapg_row
 	my $row        = shift;
 	my @bool_attrs = @_;
 
+	# Replace empty string by zero char constant
+	$row->{attidentity} ||= '\0';
+
 	# Supply appropriate quoting for these fields.
 	$row->{attname}    = q|{"| . $row->{attname} . q|"}|;
 	$row->{attstorage} = q|'| . $row->{attstorage} . q|'|;
 	$row->{attalign}   = q|'| . $row->{attalign} . q|'|;
+	$row->{attidentity} = q|'| . $row->{attidentity} . q|'|;
 
 	# We don't emit initializers for the variable length fields at all.
 	# Only the fixed-size portions of the descriptors are ever used.
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index eee5e2f6ca..fcc717038d 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -144,37 +144,37 @@ static List *insert_ordered_unique_oid(List *list, Oid datum);
 static FormData_pg_attribute a1 = {
 	0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
 	SelfItemPointerAttributeNumber, 0, -1, -1,
-	false, 'p', 's', true, false, false, true, 0
+	false, 'p', 's', true, false, '\0', false, true, 0
 };
 
 static FormData_pg_attribute a2 = {
 	0, {"oid"}, OIDOID, 0, sizeof(Oid),
 	ObjectIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 static FormData_pg_attribute a3 = {
 	0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
 	MinTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 static FormData_pg_attribute a4 = {
 	0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
 	MinCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 static FormData_pg_attribute a5 = {
 	0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
 	MaxTransactionIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 static FormData_pg_attribute a6 = {
 	0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
 	MaxCommandIdAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 /*
@@ -186,7 +186,7 @@ static FormData_pg_attribute a6 = {
 static FormData_pg_attribute a7 = {
 	0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
 	TableOidAttributeNumber, 0, -1, -1,
-	true, 'p', 'i', true, false, false, true, 0
+	true, 'p', 'i', true, false, '\0', false, true, 0
 };
 
 static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};
@@ -620,6 +620,7 @@ InsertPgAttributeTuple(Relation pg_attribute_rel,
 	values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
 	values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
 	values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
+	values[Anum_pg_attribute_attidentity - 1] = CharGetDatum(new_attribute->attidentity);
 	values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
 	values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
 	values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 1eb163f539..2328b92b4e 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -353,6 +353,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			to->attcacheoff = -1;
 			to->attnotnull = false;
 			to->atthasdef = false;
+			to->attidentity = '\0';
 			to->attislocal = true;
 			to->attinhcount = 0;
 			to->attcollation = collationObjectId[i];
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index fa2a88fc5c..2185734b48 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -728,13 +728,13 @@ CREATE VIEW columns AS
            CAST(a.attnum AS sql_identifier) AS dtd_identifier,
            CAST('NO' AS yes_or_no) AS is_self_referencing,
 
-           CAST('NO' AS yes_or_no) AS is_identity,
-           CAST(null AS character_data) AS identity_generation,
-           CAST(null AS character_data) AS identity_start,
-           CAST(null AS character_data) AS identity_increment,
-           CAST(null AS character_data) AS identity_maximum,
-           CAST(null AS character_data) AS identity_minimum,
-           CAST(null AS yes_or_no) AS identity_cycle,
+           CAST(CASE WHEN a.attidentity IN ('a', 'd') THEN 'YES' ELSE 'NO' END AS yes_or_no) AS is_identity,
+           CAST(CASE a.attidentity WHEN 'a' THEN 'ALWAYS' WHEN 'd' THEN 'BY DEFAULT' END AS character_data) AS identity_generation,
+           CAST(seq.seqstart AS character_data) AS identity_start,
+           CAST(seq.seqincrement AS character_data) AS identity_increment,
+           CAST(seq.seqmax AS character_data) AS identity_maximum,
+           CAST(seq.seqmin AS character_data) AS identity_minimum,
+           CAST(CASE WHEN seq.seqcycle THEN 'YES' ELSE 'NO' END AS yes_or_no) AS identity_cycle,
 
            CAST('NEVER' AS character_data) AS is_generated,
            CAST(null AS character_data) AS generation_expression,
@@ -751,6 +751,8 @@ CREATE VIEW columns AS
            ON (t.typtype = 'd' AND t.typbasetype = bt.oid)
          LEFT JOIN (pg_collation co JOIN pg_namespace nco ON (co.collnamespace = nco.oid))
            ON a.attcollation = co.oid AND (nco.nspname, co.collname) <> ('pg_catalog', 'default')
+         LEFT JOIN (pg_depend dep JOIN pg_sequence seq ON (dep.classid = 'pg_class'::regclass AND dep.objid = seq.seqrelid AND dep.deptype = 'i'))
+           ON (dep.refclassid = 'pg_class'::regclass AND dep.refobjid = c.oid AND dep.refobjsubid = a.attnum)
 
     WHERE (NOT pg_is_other_temp_schema(nc.oid))
 
@@ -1545,6 +1547,7 @@ CREATE VIEW sequences AS
     FROM pg_namespace nc, pg_class c, pg_sequence s
     WHERE c.relnamespace = nc.oid
           AND c.relkind = 'S'
+          AND NOT EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND deptype = 'i')
           AND (NOT pg_is_other_temp_schema(nc.oid))
           AND c.oid = s.seqrelid
           AND (pg_has_role(c.relowner, 'USAGE')
diff --git a/src/backend/catalog/pg_depend.c b/src/backend/catalog/pg_depend.c
index d0ee851215..aae879e355 100644
--- a/src/backend/catalog/pg_depend.c
+++ b/src/backend/catalog/pg_depend.c
@@ -488,7 +488,7 @@ getExtensionOfObject(Oid classId, Oid objectId)
 /*
  * Detect whether a sequence is marked as "owned" by a column
  *
- * An ownership marker is an AUTO dependency from the sequence to the
+ * An ownership marker is an AUTO or INTERNAL dependency from the sequence to the
  * column.  If we find one, store the identity of the owning column
  * into *tableId and *colId and return TRUE; else return FALSE.
  *
@@ -497,7 +497,7 @@ getExtensionOfObject(Oid classId, Oid objectId)
  * not happen, though.
  */
 bool
-sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
+sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId)
 {
 	bool		ret = false;
 	Relation	depRel;
@@ -524,7 +524,7 @@ sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
 		Form_pg_depend depform = (Form_pg_depend) GETSTRUCT(tup);
 
 		if (depform->refclassid == RelationRelationId &&
-			depform->deptype == DEPENDENCY_AUTO)
+			depform->deptype == deptype)
 		{
 			*tableId = depform->refobjid;
 			*colId = depform->refobjsubid;
@@ -541,27 +541,15 @@ sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId)
 }
 
 /*
- * Remove any existing "owned" markers for the specified sequence.
- *
- * Note: we don't provide a special function to install an "owned"
- * marker; just use recordDependencyOn().
- */
-void
-markSequenceUnowned(Oid seqId)
-{
-	deleteDependencyRecordsForClass(RelationRelationId, seqId,
-									RelationRelationId, DEPENDENCY_AUTO);
-}
-
-/*
- * Collect a list of OIDs of all sequences owned by the specified relation.
+ * Collect a list of OIDs of all sequences owned by the specified relation,
+ * and column if specified.
  */
 List *
-getOwnedSequences(Oid relid)
+getOwnedSequences(Oid relid, AttrNumber attnum)
 {
 	List	   *result = NIL;
 	Relation	depRel;
-	ScanKeyData key[2];
+	ScanKeyData key[3];
 	SysScanDesc scan;
 	HeapTuple	tup;
 
@@ -575,23 +563,28 @@ getOwnedSequences(Oid relid)
 				Anum_pg_depend_refobjid,
 				BTEqualStrategyNumber, F_OIDEQ,
 				ObjectIdGetDatum(relid));
+	if (attnum)
+		ScanKeyInit(&key[2],
+					Anum_pg_depend_refobjsubid,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(attnum));
 
 	scan = systable_beginscan(depRel, DependReferenceIndexId, true,
-							  NULL, 2, key);
+							  NULL, attnum ? 3 : 2, key);
 
 	while (HeapTupleIsValid(tup = systable_getnext(scan)))
 	{
 		Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
 
 		/*
-		 * We assume any auto dependency of a sequence on a column must be
+		 * We assume any auto or internal dependency of a sequence on a column must be
 		 * what we are looking for.  (We need the relkind test because indexes
 		 * can also have auto dependencies on columns.)
 		 */
 		if (deprec->classid == RelationRelationId &&
 			deprec->objsubid == 0 &&
 			deprec->refobjsubid != 0 &&
-			deprec->deptype == DEPENDENCY_AUTO &&
+			(deprec->deptype == DEPENDENCY_AUTO || deprec->deptype == DEPENDENCY_INTERNAL) &&
 			get_rel_relkind(deprec->objid) == RELKIND_SEQUENCE)
 		{
 			result = lappend_oid(result, deprec->objid);
@@ -605,6 +598,21 @@ getOwnedSequences(Oid relid)
 	return result;
 }
 
+/*
+ * Get owned sequence, error if not exactly one.
+ */
+Oid
+getOwnedSequence(Oid relid, AttrNumber attnum)
+{
+	List	   *seqlist = getOwnedSequences(relid, attnum);
+
+	if (list_length(seqlist) > 1)
+		elog(ERROR, "more than one owned sequence found");
+	else if (list_length(seqlist) < 1)
+		elog(ERROR, "no owned sequence found");
+	else
+		return linitial_oid(seqlist);
+}
 
 /*
  * get_constraint_index
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 8956ba9304..2821b9b702 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -200,7 +200,7 @@ F181	Multiple module support			NO
 F191	Referential delete actions			YES	
 F200	TRUNCATE TABLE statement			YES	
 F201	CAST function			YES	
-F202	TRUNCATE TABLE: identity column restart option			NO	
+F202	TRUNCATE TABLE: identity column restart option			YES	
 F221	Explicit defaults			YES	
 F222	INSERT statement: DEFAULT VALUES clause			YES	
 F231	Privilege tables			YES	
@@ -241,9 +241,9 @@ F381	Extended schema manipulation	02	ALTER TABLE statement: ADD CONSTRAINT claus
 F381	Extended schema manipulation	03	ALTER TABLE statement: DROP CONSTRAINT clause	YES	
 F382	Alter column data type			YES	
 F383	Set column not null clause			YES	
-F384	Drop identity property clause			NO	
+F384	Drop identity property clause			YES	
 F385	Drop column generation expression clause			NO	
-F386	Set identity column generation clause			NO	
+F386	Set identity column generation clause			YES	
 F391	Long identifiers			YES	
 F392	Unicode escapes in identifiers			YES	
 F393	Unicode escapes in literals			YES	
@@ -420,11 +420,11 @@ T152	DISTINCT predicate with negation			YES
 T171	LIKE clause in table definition			YES	
 T172	AS subquery clause in table definition			YES	
 T173	Extended LIKE clause in table definition			YES	
-T174	Identity columns			NO	
+T174	Identity columns			YES	
 T175	Generated columns			NO	
 T176	Sequence generator support			NO	
-T177	Sequence generator support: simple restart option			NO	
-T178	Identity columns:  simple restart option			NO	
+T177	Sequence generator support: simple restart option			YES	
+T178	Identity columns:  simple restart option			YES	
 T180	System-versioned tables			NO	
 T181	Application-time period tables			NO	
 T191	Referential action RESTRICT			YES	
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index d547db714e..e443755f0a 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -93,17 +93,17 @@ static HTAB *seqhashtab = NULL; /* hash table for SeqTable items */
 static SeqTableData *last_used_seq = NULL;
 
 static void fill_seq_with_data(Relation rel, HeapTuple tuple);
-static int64 nextval_internal(Oid relid);
 static Relation open_share_lock(SeqTable seq);
 static void create_seq_hashtable(void);
 static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
 static Form_pg_sequence_data read_seq_tuple(Relation rel,
 			   Buffer *buf, HeapTuple seqdatatuple);
-static void init_params(ParseState *pstate, List *options, bool isInit,
+static void init_params(ParseState *pstate, List *options, bool for_identity,
+						bool isInit,
 						Form_pg_sequence seqform,
 						Form_pg_sequence_data seqdataform, List **owned_by);
 static void do_setval(Oid relid, int64 next, bool iscalled);
-static void process_owned_by(Relation seqrel, List *owned_by);
+static void process_owned_by(Relation seqrel, List *owned_by, bool for_identity);
 
 
 /*
@@ -153,7 +153,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 	}
 
 	/* Check and set all option values */
-	init_params(pstate, seq->options, true, &seqform, &seqdataform, &owned_by);
+	init_params(pstate, seq->options, seq->for_identity, true, &seqform, &seqdataform, &owned_by);
 
 	/*
 	 * Create relation (and fill value[] and null[] for the tuple)
@@ -219,7 +219,7 @@ DefineSequence(ParseState *pstate, CreateSeqStmt *seq)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(rel, owned_by);
+		process_owned_by(rel, owned_by, seq->for_identity);
 
 	heap_close(rel, NoLock);
 
@@ -455,7 +455,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 	seqform = (Form_pg_sequence) GETSTRUCT(tuple);
 
 	/* Check and set new values */
-	init_params(pstate, stmt->options, false, seqform, &newseqdata, &owned_by);
+	init_params(pstate, stmt->options, stmt->for_identity, false, seqform, &newseqdata, &owned_by);
 
 	/* Clear local cache so that we don't think we have cached numbers */
 	/* Note that we do not change the currval() state */
@@ -498,7 +498,7 @@ AlterSequence(ParseState *pstate, AlterSeqStmt *stmt)
 
 	/* process OWNED BY if given */
 	if (owned_by)
-		process_owned_by(seqrel, owned_by);
+		process_owned_by(seqrel, owned_by, stmt->for_identity);
 
 	InvokeObjectPostAlterHook(RelationRelationId, relid, 0);
 
@@ -554,7 +554,7 @@ nextval(PG_FUNCTION_ARGS)
 	 */
 	relid = RangeVarGetRelid(sequence, NoLock, false);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
 Datum
@@ -562,11 +562,11 @@ nextval_oid(PG_FUNCTION_ARGS)
 {
 	Oid			relid = PG_GETARG_OID(0);
 
-	PG_RETURN_INT64(nextval_internal(relid));
+	PG_RETURN_INT64(nextval_internal(relid, true));
 }
 
-static int64
-nextval_internal(Oid relid)
+int64
+nextval_internal(Oid relid, bool check_permissions)
 {
 	SeqTable	elm;
 	Relation	seqrel;
@@ -592,7 +592,8 @@ nextval_internal(Oid relid)
 	/* open and AccessShareLock sequence */
 	init_sequence(relid, &elm, &seqrel);
 
-	if (pg_class_aclcheck(elm->relid, GetUserId(),
+	if (check_permissions &&
+		pg_class_aclcheck(elm->relid, GetUserId(),
 						  ACL_USAGE | ACL_UPDATE) != ACLCHECK_OK)
 		ereport(ERROR,
 				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@@ -1219,7 +1220,8 @@ read_seq_tuple(Relation rel, Buffer *buf, HeapTuple seqdatatuple)
  * otherwise, do not change existing options that aren't explicitly overridden.
  */
 static void
-init_params(ParseState *pstate, List *options, bool isInit,
+init_params(ParseState *pstate, List *options, bool for_identity,
+			bool isInit,
 			Form_pg_sequence seqform,
 			Form_pg_sequence_data seqdataform, List **owned_by)
 {
@@ -1320,6 +1322,18 @@ init_params(ParseState *pstate, List *options, bool isInit,
 						 parser_errposition(pstate, defel->location)));
 			*owned_by = defGetQualifiedName(defel);
 		}
+		else if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			/*
+			 * The parser allows this, but it is only for identity columns, in
+			 * which case it is filtered out in parse_utilcmd.c.  We only get
+			 * here if someone puts it into a CREATE SEQUENCE.
+			 */
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("invalid sequence option SEQUENCE NAME"),
+					 parser_errposition(pstate, defel->location)));
+		}
 		else
 			elog(ERROR, "option \"%s\" not recognized",
 				 defel->defname);
@@ -1341,7 +1355,9 @@ init_params(ParseState *pstate, List *options, bool isInit,
 			seqform->seqtypid != INT8OID)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-					 errmsg("sequence type must be smallint, integer, or bigint")));
+					 for_identity
+					 ? errmsg("identity column type must be smallint, integer, or bigint")
+					 : errmsg("sequence type must be smallint, integer, or bigint")));
 	}
 	else if (isInit)
 		seqform->seqtypid = INT8OID;
@@ -1565,12 +1581,15 @@ init_params(ParseState *pstate, List *options, bool isInit,
  * as the sequence.
  */
 static void
-process_owned_by(Relation seqrel, List *owned_by)
+process_owned_by(Relation seqrel, List *owned_by, bool for_identity)
 {
+	DependencyType deptype;
 	int			nnames;
 	Relation	tablerel;
 	AttrNumber	attnum;
 
+	deptype = for_identity ? DEPENDENCY_INTERNAL : DEPENDENCY_AUTO;
+
 	nnames = list_length(owned_by);
 	Assert(nnames > 0);
 	if (nnames == 1)
@@ -1601,6 +1620,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		/* Must be a regular or foreign table */
 		if (!(tablerel->rd_rel->relkind == RELKIND_RELATION ||
 			  tablerel->rd_rel->relkind == RELKIND_FOREIGN_TABLE ||
+			  tablerel->rd_rel->relkind == RELKIND_VIEW ||
 			  tablerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
 			ereport(ERROR,
 					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
@@ -1627,10 +1647,28 @@ process_owned_by(Relation seqrel, List *owned_by)
 	}
 
 	/*
-	 * OK, we are ready to update pg_depend.  First remove any existing AUTO
+	 * Catch user explicitly running OWNED BY on identity sequence.
+	 */
+	if (deptype == DEPENDENCY_AUTO)
+	{
+		Oid			tableId;
+		int32		colId;
+
+		if (sequenceIsOwned(RelationGetRelid(seqrel), DEPENDENCY_INTERNAL, &tableId, &colId))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot change ownership of identity sequence"),
+					 errdetail("Sequence \"%s\" is linked to table \"%s\".",
+							   RelationGetRelationName(seqrel),
+							   get_rel_name(tableId))));
+	}
+
+	/*
+	 * OK, we are ready to update pg_depend.  First remove any existing
 	 * dependencies for the sequence, then optionally add a new one.
 	 */
-	markSequenceUnowned(RelationGetRelid(seqrel));
+	deleteDependencyRecordsForClass(RelationRelationId, RelationGetRelid(seqrel),
+									RelationRelationId, deptype);
 
 	if (tablerel)
 	{
@@ -1643,7 +1681,7 @@ process_owned_by(Relation seqrel, List *owned_by)
 		depobject.classId = RelationRelationId;
 		depobject.objectId = RelationGetRelid(seqrel);
 		depobject.objectSubId = 0;
-		recordDependencyOn(&depobject, &refobject, DEPENDENCY_AUTO);
+		recordDependencyOn(&depobject, &refobject, deptype);
 	}
 
 	/* Done, but hold lock until commit */
@@ -1653,6 +1691,33 @@ process_owned_by(Relation seqrel, List *owned_by)
 
 
 /*
+ * Return sequence parameters in a list of the form created by the parser.
+ */
+List *
+sequence_options(Oid relid)
+{
+	HeapTuple	pgstuple;
+	Form_pg_sequence pgsform;
+	List	   *options = NIL;
+
+	pgstuple = SearchSysCache1(SEQRELID, relid);
+	if (!HeapTupleIsValid(pgstuple))
+		elog(ERROR, "cache lookup failed for sequence %u", relid);
+	pgsform = (Form_pg_sequence) GETSTRUCT(pgstuple);
+
+	options = lappend(options, makeDefElem("cache", (Node *) makeInteger(pgsform->seqcache), -1));
+	options = lappend(options, makeDefElem("cycle", (Node *) makeInteger(pgsform->seqcycle), -1));
+	options = lappend(options, makeDefElem("increment", (Node *) makeInteger(pgsform->seqincrement), -1));
+	options = lappend(options, makeDefElem("maxvalue", (Node *) makeInteger(pgsform->seqmax), -1));
+	options = lappend(options, makeDefElem("minvalue", (Node *) makeInteger(pgsform->seqmin), -1));
+	options = lappend(options, makeDefElem("start", (Node *) makeInteger(pgsform->seqstart), -1));
+
+	ReleaseSysCache(pgstuple);
+
+	return options;
+}
+
+/*
  * Return sequence parameters (formerly for use by information schema)
  */
 Datum
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 4cf2efb2ad..0f40df33a5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -361,6 +361,11 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
+static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
+					Node *def, LOCKMODE lockmode);
+static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
 static ObjectAddress ATExecSetStatistics(Relation rel, const char *colName,
@@ -696,6 +701,9 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			cookedDefaults = lappend(cookedDefaults, cooked);
 			descriptor->attrs[attnum - 1]->atthasdef = true;
 		}
+
+		if (colDef->identity)
+			descriptor->attrs[attnum - 1]->attidentity = colDef->identity;
 	}
 
 	/*
@@ -1281,7 +1289,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 		foreach(cell, rels)
 		{
 			Relation	rel = (Relation) lfirst(cell);
-			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel));
+			List	   *seqlist = getOwnedSequences(RelationGetRelid(rel), 0);
 			ListCell   *seqcell;
 
 			foreach(seqcell, seqlist)
@@ -2078,6 +2086,12 @@ MergeAttributes(List *schema, List *supers, char relpersistence,
 									   get_collation_name(defcollid),
 									   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;
+
 				/* Copy storage parameter */
 				if (def->storage == 0)
 					def->storage = newdef->storage;
@@ -3217,6 +3231,9 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
+			case AT_AddIdentity:
+			case AT_DropIdentity:
+			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -3447,6 +3464,18 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
+		case AT_AddIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_ADD_CONSTR;
+			break;
+		case AT_DropIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_DROP;
+			break;
+		case AT_SetIdentity:
+			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
+			pass = AT_PASS_COL_ATTRS;
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			ATSimplePermissions(rel, ATT_TABLE | ATT_FOREIGN_TABLE);
 			ATPrepDropNotNull(rel, recurse, recursing);
@@ -3772,6 +3801,15 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
+		case AT_AddIdentity:
+			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_SetIdentity:
+			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			break;
+		case AT_DropIdentity:
+			address = ATExecDropIdentity(rel, cmd->name, cmd->missing_ok, lockmode);
+			break;
 		case AT_DropNotNull:	/* ALTER COLUMN DROP NOT NULL */
 			address = ATExecDropNotNull(rel, cmd->name, lockmode);
 			break;
@@ -5120,6 +5158,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		elog(ERROR, "cache lookup failed for relation %u", myrelid);
 	relkind = ((Form_pg_class) GETSTRUCT(reltup))->relkind;
 
+	/*
+	 * Cannot add identity column if table has children, because identity does
+	 * not inherit.  (Adding column and identity separately will work.)
+	 */
+	if (colDef->identity &&
+		recurse &&
+		find_inheritance_children(myrelid, NoLock) != NIL)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+				 errmsg("cannot recursively add identity column to table that has child tables")));
+
 	/* skip if the name already exists and if_not_exists is true */
 	if (!check_for_column_name_collision(rel, colDef->colname, if_not_exists))
 	{
@@ -5172,6 +5221,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	attribute.attalign = tform->typalign;
 	attribute.attnotnull = colDef->is_not_null;
 	attribute.atthasdef = false;
+	attribute.attidentity = colDef->identity;
 	attribute.attisdropped = false;
 	attribute.attislocal = colDef->is_local;
 	attribute.attinhcount = colDef->inhcount;
@@ -5539,6 +5589,12 @@ ATExecDropNotNull(Relation rel, const char *colName, LOCKMODE lockmode)
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel))));
+
 	/*
 	 * Check that the attribute is not in a primary key
 	 *
@@ -5755,6 +5811,13 @@ ATExecColumnDefault(Relation rel, const char *colName,
 				 errmsg("cannot alter system column \"%s\"",
 						colName)));
 
+	if (get_attidentity(RelationGetRelid(rel), attnum))
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("column \"%s\" of relation \"%s\" is an identity column",
+						colName, RelationGetRelationName(rel)),
+				 newDefault ? 0 : errhint("Use ALTER TABLE ... ALTER COLUMN ... DROP IDENTITY instead.")));
+
 	/*
 	 * Remove any old default for the column.  We use RESTRICT here for
 	 * safety, but at present we do not expect anything to depend on the
@@ -5790,6 +5853,224 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
+ * ALTER TABLE ALTER COLUMN ADD IDENTITY
+ *
+ * Return the address of the affected column.
+ */
+static ObjectAddress
+ATExecAddIdentity(Relation rel, const char *colName,
+				  Node *def, LOCKMODE lockmode)
+{
+	Relation	attrelation;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	ObjectAddress address;
+	ColumnDef  *cdef = castNode(ColumnDef, def);
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	/* Can't alter a system attribute */
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	/*
+	 * Creating a column as identity implies NOT NULL, so adding the identity
+	 * to an existing column that is not NOT NULL would create a state that
+	 * cannot be reproduced without contortions.
+	 */
+	if (!attTup->attnotnull)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->attidentity)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is already an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (attTup->atthasdef)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+						colName, RelationGetRelationName(rel))));
+
+	attTup->attidentity = cdef->identity;
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+{
+	ListCell   *option;
+	DefElem	   *generatedEl = NULL;
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+
+	foreach(option, castNode(List, def))
+	{
+		DefElem	   *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "generated") == 0)
+		{
+			if (generatedEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			generatedEl = defel;
+		}
+		else
+			elog(ERROR, "option \"%s\" not recognized",
+				 defel->defname);
+	}
+
+	/*
+	 * Even if there is nothing to change here, we run all the checks.  There
+	 * will be a subsequent ALTER SEQUENCE that relies on everything being
+	 * there.
+	 */
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (!attTup->attidentity)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+						colName, RelationGetRelationName(rel))));
+
+	if (generatedEl)
+	{
+		attTup->attidentity = defGetInt32(generatedEl);
+		CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+		InvokeObjectPostAlterHook(RelationRelationId,
+								  RelationGetRelid(rel),
+								  attTup->attnum);
+		ObjectAddressSubSet(address, RelationRelationId,
+							RelationGetRelid(rel), attnum);
+	}
+
+	heap_freetuple(tuple);
+	heap_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+static ObjectAddress
+ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode)
+{
+	HeapTuple	tuple;
+	Form_pg_attribute attTup;
+	AttrNumber	attnum;
+	Relation	attrelation;
+	ObjectAddress address;
+	Oid			seqid;
+	ObjectAddress seqaddress;
+
+	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
+	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						colName, RelationGetRelationName(rel))));
+
+	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
+	attnum = attTup->attnum;
+
+	if (attnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("cannot alter system column \"%s\"",
+						colName)));
+
+	if (!attTup->attidentity)
+	{
+		if (!missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+							colName, RelationGetRelationName(rel))));
+		else
+		{
+			ereport(NOTICE,
+					(errmsg("column \"%s\" of relation \"%s\" is not an identity column, skipping",
+							colName, RelationGetRelationName(rel))));
+			heap_freetuple(tuple);
+			heap_close(attrelation, RowExclusiveLock);
+			return InvalidObjectAddress;
+		}
+	}
+
+	attTup->attidentity = '\0';
+	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
+
+	InvokeObjectPostAlterHook(RelationRelationId,
+							  RelationGetRelid(rel),
+							  attTup->attnum);
+	ObjectAddressSubSet(address, RelationRelationId,
+						RelationGetRelid(rel), attnum);
+	heap_freetuple(tuple);
+
+	heap_close(attrelation, RowExclusiveLock);
+
+	/* drop the internal sequence */
+	seqid = getOwnedSequence(RelationGetRelid(rel), attnum);
+	deleteDependencyRecordsForClass(RelationRelationId, seqid,
+									RelationRelationId, DEPENDENCY_INTERNAL);
+	CommandCounterIncrement();
+	seqaddress.classId = RelationRelationId;
+	seqaddress.objectId = seqid;
+	seqaddress.objectSubId = 0;
+	performDeletion(&seqaddress, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
+
+	return address;
+}
+
+/*
  * ALTER TABLE ALTER COLUMN SET STATISTICS
  */
 static void
@@ -9535,7 +9816,8 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lock
 				Oid			tableId;
 				int32		colId;
 
-				if (sequenceIsOwned(relationOid, &tableId, &colId))
+				if (sequenceIsOwned(relationOid, DEPENDENCY_AUTO, &tableId, &colId) ||
+					sequenceIsOwned(relationOid, DEPENDENCY_INTERNAL, &tableId, &colId))
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 							 errmsg("cannot change owner of sequence \"%s\"",
@@ -9806,7 +10088,7 @@ change_owner_recurse_to_sequences(Oid relationOid, Oid newOwnerId, LOCKMODE lock
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;
 
 		/* Use relation_open just in case it's an index */
@@ -12111,7 +12393,8 @@ AlterTableNamespace(AlterObjectSchemaStmt *stmt, Oid *oldschema)
 		Oid			tableId;
 		int32		colId;
 
-		if (sequenceIsOwned(relid, &tableId, &colId))
+		if (sequenceIsOwned(relid, DEPENDENCY_AUTO, &tableId, &colId) ||
+			sequenceIsOwned(relid, DEPENDENCY_INTERNAL, &tableId, &colId))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("cannot move an owned sequence into another schema"),
@@ -12294,7 +12577,7 @@ AlterIndexNamespaces(Relation classRel, Relation rel,
 }
 
 /*
- * Move all SERIAL-column sequences of the specified relation to another
+ * Move all identity and SERIAL-column sequences of the specified relation to another
  * namespace.
  *
  * Note: we assume adequate permission checking was done by the caller,
@@ -12338,7 +12621,7 @@ AlterSeqNamespaces(Relation classRel, Relation rel,
 		if (depForm->refobjsubid == 0 ||
 			depForm->classid != RelationRelationId ||
 			depForm->objsubid != 0 ||
-			depForm->deptype != DEPENDENCY_AUTO)
+			!(depForm->deptype == DEPENDENCY_AUTO || depForm->deptype == DEPENDENCY_INTERNAL))
 			continue;
 
 		/* Use relation_open just in case it's an index */
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index 5a84742d14..d35ea7664d 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -1993,6 +1993,17 @@ ExecInitExprRec(Expr *node, PlanState *parent, ExprState *state,
 				break;
 			}
 
+		case T_NextValueExpr:
+			{
+				NextValueExpr *nve = (NextValueExpr *) node;
+
+				scratch.opcode = EEOP_NEXTVALUEEXPR;
+				scratch.d.nextvalueexpr.seqid = nve->seqid;
+
+				ExprEvalPushStep(state, &scratch);
+				break;
+			}
+
 		default:
 			elog(ERROR, "unrecognized node type: %d",
 				 (int) nodeTag(node));
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 4fbb5c1e74..5935b9ef75 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -60,6 +60,7 @@
 
 #include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
+#include "commands/sequence.h"
 #include "executor/execExpr.h"
 #include "executor/nodeSubplan.h"
 #include "funcapi.h"
@@ -337,6 +338,7 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 		&&CASE_EEOP_NULLIF,
 		&&CASE_EEOP_SQLVALUEFUNCTION,
 		&&CASE_EEOP_CURRENTOFEXPR,
+		&&CASE_EEOP_NEXTVALUEEXPR,
 		&&CASE_EEOP_ARRAYEXPR,
 		&&CASE_EEOP_ARRAYCOERCE,
 		&&CASE_EEOP_ROW,
@@ -1228,6 +1230,14 @@ ExecInterpExpr(ExprState *state, ExprContext *econtext, bool *isnull)
 			EEO_NEXT();
 		}
 
+		EEO_CASE(EEOP_NEXTVALUEEXPR)
+		{
+			*op->resvalue = Int64GetDatum(nextval_internal(op->d.nextvalueexpr.seqid, false));
+			*op->resnull = false;
+
+			EEO_NEXT();
+		}
+
 		EEO_CASE(EEOP_ARRAYEXPR)
 		{
 			/* too complex for an inline implementation */
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 1c88d601bd..b31fe146e4 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1982,6 +1982,20 @@ _copyCurrentOfExpr(const CurrentOfExpr *from)
 	return newnode;
 }
 
+ /*
+  * _copyNextValueExpr
+  */
+static NextValueExpr *
+_copyNextValueExpr(const NextValueExpr *from)
+{
+	NextValueExpr *newnode = makeNode(NextValueExpr);
+
+	COPY_SCALAR_FIELD(seqid);
+	COPY_SCALAR_FIELD(typeId);
+
+	return newnode;
+}
+
 /*
  * _copyInferenceElem
  */
@@ -2768,6 +2782,7 @@ _copyColumnDef(const ColumnDef *from)
 	COPY_SCALAR_FIELD(storage);
 	COPY_NODE_FIELD(raw_default);
 	COPY_NODE_FIELD(cooked_default);
+	COPY_SCALAR_FIELD(identity);
 	COPY_NODE_FIELD(collClause);
 	COPY_SCALAR_FIELD(collOid);
 	COPY_NODE_FIELD(constraints);
@@ -2790,6 +2805,7 @@ _copyConstraint(const Constraint *from)
 	COPY_SCALAR_FIELD(is_no_inherit);
 	COPY_NODE_FIELD(raw_expr);
 	COPY_STRING_FIELD(cooked_expr);
+	COPY_SCALAR_FIELD(generated_when);
 	COPY_NODE_FIELD(keys);
 	COPY_NODE_FIELD(exclusions);
 	COPY_NODE_FIELD(options);
@@ -2898,6 +2914,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
 	COPY_NODE_FIELD(targetList);
+	COPY_SCALAR_FIELD(override);
 	COPY_NODE_FIELD(onConflict);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(groupClause);
@@ -2941,6 +2958,7 @@ _copyInsertStmt(const InsertStmt *from)
 	COPY_NODE_FIELD(onConflictClause);
 	COPY_NODE_FIELD(returningList);
 	COPY_NODE_FIELD(withClause);
+	COPY_SCALAR_FIELD(override);
 
 	return newnode;
 }
@@ -3789,6 +3807,7 @@ _copyCreateSeqStmt(const CreateSeqStmt *from)
 	COPY_NODE_FIELD(sequence);
 	COPY_NODE_FIELD(options);
 	COPY_SCALAR_FIELD(ownerId);
+	COPY_SCALAR_FIELD(for_identity);
 	COPY_SCALAR_FIELD(if_not_exists);
 
 	return newnode;
@@ -3801,6 +3820,7 @@ _copyAlterSeqStmt(const AlterSeqStmt *from)
 
 	COPY_NODE_FIELD(sequence);
 	COPY_NODE_FIELD(options);
+	COPY_SCALAR_FIELD(for_identity);
 	COPY_SCALAR_FIELD(missing_ok);
 
 	return newnode;
@@ -4902,6 +4922,9 @@ copyObjectImpl(const void *from)
 		case T_CurrentOfExpr:
 			retval = _copyCurrentOfExpr(from);
 			break;
+		case T_NextValueExpr:
+			retval = _copyNextValueExpr(from);
+			break;
 		case T_InferenceElem:
 			retval = _copyInferenceElem(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 5941b7a2bf..46573ae767 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -734,6 +734,15 @@ _equalCurrentOfExpr(const CurrentOfExpr *a, const CurrentOfExpr *b)
 }
 
 static bool
+_equalNextValueExpr(const NextValueExpr *a, const NextValueExpr *b)
+{
+	COMPARE_SCALAR_FIELD(seqid);
+	COMPARE_SCALAR_FIELD(typeId);
+
+	return true;
+}
+
+static bool
 _equalInferenceElem(const InferenceElem *a, const InferenceElem *b)
 {
 	COMPARE_NODE_FIELD(expr);
@@ -963,6 +972,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
 	COMPARE_NODE_FIELD(targetList);
+	COMPARE_SCALAR_FIELD(override);
 	COMPARE_NODE_FIELD(onConflict);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(groupClause);
@@ -1002,6 +1012,7 @@ _equalInsertStmt(const InsertStmt *a, const InsertStmt *b)
 	COMPARE_NODE_FIELD(onConflictClause);
 	COMPARE_NODE_FIELD(returningList);
 	COMPARE_NODE_FIELD(withClause);
+	COMPARE_SCALAR_FIELD(override);
 
 	return true;
 }
@@ -1713,6 +1724,7 @@ _equalCreateSeqStmt(const CreateSeqStmt *a, const CreateSeqStmt *b)
 	COMPARE_NODE_FIELD(sequence);
 	COMPARE_NODE_FIELD(options);
 	COMPARE_SCALAR_FIELD(ownerId);
+	COMPARE_SCALAR_FIELD(for_identity);
 	COMPARE_SCALAR_FIELD(if_not_exists);
 
 	return true;
@@ -1723,6 +1735,7 @@ _equalAlterSeqStmt(const AlterSeqStmt *a, const AlterSeqStmt *b)
 {
 	COMPARE_NODE_FIELD(sequence);
 	COMPARE_NODE_FIELD(options);
+	COMPARE_SCALAR_FIELD(for_identity);
 	COMPARE_SCALAR_FIELD(missing_ok);
 
 	return true;
@@ -2530,6 +2543,7 @@ _equalColumnDef(const ColumnDef *a, const ColumnDef *b)
 	COMPARE_SCALAR_FIELD(storage);
 	COMPARE_NODE_FIELD(raw_default);
 	COMPARE_NODE_FIELD(cooked_default);
+	COMPARE_SCALAR_FIELD(identity);
 	COMPARE_NODE_FIELD(collClause);
 	COMPARE_SCALAR_FIELD(collOid);
 	COMPARE_NODE_FIELD(constraints);
@@ -2550,6 +2564,7 @@ _equalConstraint(const Constraint *a, const Constraint *b)
 	COMPARE_SCALAR_FIELD(is_no_inherit);
 	COMPARE_NODE_FIELD(raw_expr);
 	COMPARE_STRING_FIELD(cooked_expr);
+	COMPARE_SCALAR_FIELD(generated_when);
 	COMPARE_NODE_FIELD(keys);
 	COMPARE_NODE_FIELD(exclusions);
 	COMPARE_NODE_FIELD(options);
@@ -3099,6 +3114,9 @@ equal(const void *a, const void *b)
 		case T_CurrentOfExpr:
 			retval = _equalCurrentOfExpr(a, b);
 			break;
+		case T_NextValueExpr:
+			retval = _equalNextValueExpr(a, b);
+			break;
 		case T_InferenceElem:
 			retval = _equalInferenceElem(a, b);
 			break;
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 6e52eb7231..31714fd466 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -246,6 +246,9 @@ exprType(const Node *expr)
 		case T_CurrentOfExpr:
 			type = BOOLOID;
 			break;
+		case T_NextValueExpr:
+			type = ((const NextValueExpr *) expr)->typeId;
+			break;
 		case T_InferenceElem:
 			{
 				const InferenceElem *n = (const InferenceElem *) expr;
@@ -919,6 +922,9 @@ exprCollation(const Node *expr)
 		case T_CurrentOfExpr:
 			coll = InvalidOid;	/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			coll = InvalidOid;	/* result is always an integer type */
+			break;
 		case T_InferenceElem:
 			coll = exprCollation((Node *) ((const InferenceElem *) expr)->expr);
 			break;
@@ -1122,6 +1128,9 @@ exprSetCollation(Node *expr, Oid collation)
 		case T_CurrentOfExpr:
 			Assert(!OidIsValid(collation));		/* result is always boolean */
 			break;
+		case T_NextValueExpr:
+			Assert(!OidIsValid(collation));		/* result is always an integer type */
+			break;
 		default:
 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(expr));
 			break;
@@ -1881,6 +1890,7 @@ expression_tree_walker(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
@@ -2475,6 +2485,7 @@ expression_tree_mutator(Node *node,
 		case T_CaseTestExpr:
 		case T_SetToDefault:
 		case T_CurrentOfExpr:
+		case T_NextValueExpr:
 		case T_SQLValueFunction:
 		case T_RangeTblRef:
 		case T_SortGroupClause:
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index bbb63a4bfa..8785fb5432 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -2751,6 +2751,7 @@ _outColumnDef(StringInfo str, const ColumnDef *node)
 	WRITE_CHAR_FIELD(storage);
 	WRITE_NODE_FIELD(raw_default);
 	WRITE_NODE_FIELD(cooked_default);
+	WRITE_CHAR_FIELD(identity);
 	WRITE_NODE_FIELD(collClause);
 	WRITE_OID_FIELD(collOid);
 	WRITE_NODE_FIELD(constraints);
@@ -2856,6 +2857,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
 	WRITE_NODE_FIELD(targetList);
+	WRITE_ENUM_FIELD(override, OverridingKind);
 	WRITE_NODE_FIELD(onConflict);
 	WRITE_NODE_FIELD(returningList);
 	WRITE_NODE_FIELD(groupClause);
@@ -3386,6 +3388,13 @@ _outConstraint(StringInfo str, const Constraint *node)
 			WRITE_STRING_FIELD(cooked_expr);
 			break;
 
+		case CONSTR_IDENTITY:
+			appendStringInfoString(str, "IDENTITY");
+			WRITE_NODE_FIELD(raw_expr);
+			WRITE_STRING_FIELD(cooked_expr);
+			WRITE_CHAR_FIELD(generated_when);
+			break;
+
 		case CONSTR_CHECK:
 			appendStringInfoString(str, "CHECK");
 			WRITE_BOOL_FIELD(is_no_inherit);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 474f221a75..d3ca083780 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -247,6 +247,7 @@ _readQuery(void)
 	READ_NODE_FIELD(rtable);
 	READ_NODE_FIELD(jointree);
 	READ_NODE_FIELD(targetList);
+	READ_ENUM_FIELD(override, OverridingKind);
 	READ_NODE_FIELD(onConflict);
 	READ_NODE_FIELD(returningList);
 	READ_NODE_FIELD(groupClause);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index f6025225be..118bbb231d 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -484,6 +484,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
 	}
 
+	qry->override = stmt->override;
+
 	isOnConflictUpdate = (stmt->onConflictClause &&
 						stmt->onConflictClause->action == ONCONFLICT_UPDATE);
 
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 9d53a29ad2..8643cd4524 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -292,6 +292,8 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity partition_cmd
 %type <list>	alter_table_cmds alter_type_cmds
+%type <list>    alter_identity_column_option_list
+%type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
 
@@ -449,7 +451,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				select_offset_value2 opt_select_fetch_first_value
 %type <ival>	row_or_rows first_or_next
 
-%type <list>	OptSeqOptList SeqOptList
+%type <list>	OptSeqOptList SeqOptList OptParenthesizedSeqOptList
 %type <defelt>	SeqOptElem
 
 %type <istmt>	insert_rest
@@ -569,6 +571,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				opt_frame_clause frame_extent frame_bound
 %type <str>		opt_existing_window_name
 %type <boolean> opt_if_not_exists
+%type <ival>	generated_when override_kind
 %type <partspec>	PartitionSpec OptPartitionSpec
 %type <str>			part_strategy
 %type <partelem>	part_elem
@@ -631,7 +634,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	FALSE_P FAMILY FETCH FILTER FIRST_P FLOAT_P FOLLOWING FOR
 	FORCE FOREIGN FORWARD FREEZE FROM FULL FUNCTION FUNCTIONS
 
-	GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
+	GENERATED GLOBAL GRANT GRANTED GREATEST GROUP_P GROUPING
 
 	HANDLER HAVING HEADER_P HOLD HOUR_P
 
@@ -655,7 +658,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	NULLS_P NUMERIC
 
 	OBJECT_P OF OFF OFFSET OIDS OLD ON ONLY OPERATOR OPTION OPTIONS OR
-	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OWNED OWNER
+	ORDER ORDINALITY OUT_P OUTER_P OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
 	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
@@ -726,6 +729,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * same as if they weren't keywords).  We need to do this for PARTITION,
  * RANGE, ROWS to support opt_existing_window_name; and for RANGE, ROWS
  * so that they can follow a_expr without creating postfix-operator problems;
+ * for GENERATED so that it can follow b_expr;
  * and for NULL so that it can follow b_expr in ColQualList without creating
  * postfix-operator problems.
  *
@@ -744,7 +748,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
  * blame any funny behavior of UNBOUNDED on the SQL standard, though.
  */
 %nonassoc	UNBOUNDED		/* ideally should have same precedence as IDENT */
-%nonassoc	IDENT NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
+%nonassoc	IDENT GENERATED NULL_P PARTITION RANGE ROWS PRECEDING FOLLOWING CUBE ROLLUP
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
 %left		'+' '-'
 %left		'*' '/' '%'
@@ -2128,6 +2132,49 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
+			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					Constraint *c = makeNode(Constraint);
+
+					c->contype = CONSTR_IDENTITY;
+					c->generated_when = $6;
+					c->options = $9;
+					c->location = @5;
+
+					n->subtype = AT_AddIdentity;
+					n->name = $3;
+					n->def = (Node *) c;
+
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
+			| ALTER opt_column ColId alter_identity_column_option_list
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->def = (Node *) $4;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
+			| ALTER opt_column ColId DROP IDENTITY_P
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY IF EXISTS */
+			| ALTER opt_column ColId DROP IDENTITY_P IF_P EXISTS
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropIdentity;
+					n->name = $3;
+					n->missing_ok = true;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> DROP [COLUMN] IF EXISTS <colname> [RESTRICT|CASCADE] */
 			| DROP opt_column IF_P EXISTS ColId opt_drop_behavior
 				{
@@ -2565,6 +2612,39 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_option_list:
+			alter_identity_column_option
+				{ $$ = list_make1($1); }
+			| alter_identity_column_option_list alter_identity_column_option
+				{ $$ = lappend($1, $2); }
+		;
+
+alter_identity_column_option:
+			RESTART
+				{
+					$$ = makeDefElem("restart", NULL, @1);
+				}
+			| RESTART opt_with NumericOnly
+				{
+					$$ = makeDefElem("restart", (Node *)$3, @1);
+				}
+			| SET SeqOptElem
+				{
+					if (strcmp($2->defname, "as") == 0 ||
+						strcmp($2->defname, "restart") == 0 ||
+						strcmp($2->defname, "owned_by") == 0)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("sequence option \"%s\" not supported here", $2->defname),
+								 parser_errposition(@2)));
+					$$ = $2;
+				}
+			| SET GENERATED generated_when
+				{
+					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
+				}
+		;
+
 ForValues:
 			/* a LIST partition */
 			FOR VALUES IN_P '(' partbound_datum_list ')'
@@ -3347,6 +3427,15 @@ ColConstraintElem:
 					n->cooked_expr = NULL;
 					$$ = (Node *)n;
 				}
+			| GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
+				{
+					Constraint *n = makeNode(Constraint);
+					n->contype = CONSTR_IDENTITY;
+					n->generated_when = $2;
+					n->options = $5;
+					n->location = @1;
+					$$ = (Node *)n;
+				}
 			| REFERENCES qualified_name opt_column_list key_match key_actions
 				{
 					Constraint *n = makeNode(Constraint);
@@ -3364,6 +3453,11 @@ ColConstraintElem:
 				}
 		;
 
+generated_when:
+			ALWAYS			{ $$ = ATTRIBUTE_IDENTITY_ALWAYS; }
+			| BY DEFAULT	{ $$ = ATTRIBUTE_IDENTITY_BY_DEFAULT; }
+		;
+
 /*
  * ConstraintAttr represents constraint attributes, which we parse as if
  * they were independent constraint clauses, in order to avoid shift/reduce
@@ -3430,6 +3524,7 @@ TableLikeOptionList:
 TableLikeOption:
 				DEFAULTS			{ $$ = CREATE_TABLE_LIKE_DEFAULTS; }
 				| CONSTRAINTS		{ $$ = CREATE_TABLE_LIKE_CONSTRAINTS; }
+				| IDENTITY_P		{ $$ = CREATE_TABLE_LIKE_IDENTITY; }
 				| INDEXES			{ $$ = CREATE_TABLE_LIKE_INDEXES; }
 				| STORAGE			{ $$ = CREATE_TABLE_LIKE_STORAGE; }
 				| COMMENTS			{ $$ = CREATE_TABLE_LIKE_COMMENTS; }
@@ -3967,6 +4062,10 @@ OptSeqOptList: SeqOptList							{ $$ = $1; }
 			| /*EMPTY*/								{ $$ = NIL; }
 		;
 
+OptParenthesizedSeqOptList: '(' SeqOptList ')'		{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 SeqOptList: SeqOptElem								{ $$ = list_make1($1); }
 			| SeqOptList SeqOptElem					{ $$ = lappend($1, $2); }
 		;
@@ -4011,6 +4110,11 @@ SeqOptElem: AS SimpleTypename
 				{
 					$$ = makeDefElem("owned_by", (Node *)$3, @1);
 				}
+			| SEQUENCE NAME_P any_name
+				{
+					/* not documented, only used by pg_dump */
+					$$ = makeDefElem("sequence_name", (Node *)$3, @1);
+				}
 			| START opt_with NumericOnly
 				{
 					$$ = makeDefElem("start", (Node *)$3, @1);
@@ -10412,12 +10516,26 @@ insert_rest:
 					$$->cols = NIL;
 					$$->selectStmt = $1;
 				}
+			| OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = NIL;
+					$$->override = $2;
+					$$->selectStmt = $4;
+				}
 			| '(' insert_column_list ')' SelectStmt
 				{
 					$$ = makeNode(InsertStmt);
 					$$->cols = $2;
 					$$->selectStmt = $4;
 				}
+			| '(' insert_column_list ')' OVERRIDING override_kind VALUE_P SelectStmt
+				{
+					$$ = makeNode(InsertStmt);
+					$$->cols = $2;
+					$$->override = $5;
+					$$->selectStmt = $7;
+				}
 			| DEFAULT VALUES
 				{
 					$$ = makeNode(InsertStmt);
@@ -10426,6 +10544,11 @@ insert_rest:
 				}
 		;
 
+override_kind:
+			USER		{ $$ = OVERRIDING_USER_VALUE; }
+			| SYSTEM_P	{ $$ = OVERRIDING_SYSTEM_VALUE; }
+		;
+
 insert_column_list:
 			insert_column_item
 					{ $$ = list_make1($1); }
@@ -14597,6 +14720,7 @@ unreserved_keyword:
 			| FORWARD
 			| FUNCTION
 			| FUNCTIONS
+			| GENERATED
 			| GLOBAL
 			| GRANTED
 			| HANDLER
@@ -14666,6 +14790,7 @@ unreserved_keyword:
 			| OPTIONS
 			| ORDINALITY
 			| OVER
+			| OVERRIDING
 			| OWNED
 			| OWNER
 			| PARALLEL
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 1ae43dc25d..926699608b 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -42,6 +42,7 @@
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
 #include "commands/defrem.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
@@ -356,6 +357,132 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	return result;
 }
 
+static void
+generateSerialExtraStmts(CreateStmtContext *cxt, ColumnDef *column,
+						 Oid seqtypid, List *seqoptions, bool for_identity,
+						 char **snamespace_p, char **sname_p)
+{
+	ListCell   *option;
+	DefElem	   *nameEl = NULL;
+	Oid			snamespaceid;
+	char	   *snamespace;
+	char	   *sname;
+	CreateSeqStmt *seqstmt;
+	AlterSeqStmt *altseqstmt;
+	List	   *attnamelist;
+
+	/*
+	 * Determine namespace and name to use for the sequence.
+	 *
+	 * First, check if a sequence name was passed in as an option.  This is
+	 * used by pg_dump.  Else, generate a name.
+	 *
+	 * Although we use ChooseRelationName, it's not guaranteed that the
+	 * selected sequence name won't conflict; given sufficiently long
+	 * field names, two different serial columns in the same table could
+	 * be assigned the same sequence name, and we'd not notice since we
+	 * aren't creating the sequence quite yet.  In practice this seems
+	 * quite unlikely to be a problem, especially since few people would
+	 * need two serial columns in one table.
+	 */
+
+	foreach(option, seqoptions)
+	{
+		DefElem    *defel = castNode(DefElem, lfirst(option));
+
+		if (strcmp(defel->defname, "sequence_name") == 0)
+		{
+			if (nameEl)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			nameEl = defel;
+		}
+	}
+
+	if (nameEl)
+	{
+		RangeVar *rv = makeRangeVarFromNameList(castNode(List, nameEl->arg));
+		snamespace = rv->schemaname;
+		sname = rv->relname;
+		seqoptions = list_delete_ptr(seqoptions, nameEl);
+	}
+	else
+	{
+		if (cxt->rel)
+			snamespaceid = RelationGetNamespace(cxt->rel);
+		else
+		{
+			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
+			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
+		}
+		snamespace = get_namespace_name(snamespaceid);
+		sname = ChooseRelationName(cxt->relation->relname,
+								   column->colname,
+								   "seq",
+								   snamespaceid);
+	}
+
+	ereport(DEBUG1,
+			(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
+					cxt->stmtType, sname,
+					cxt->relation->relname, column->colname)));
+
+	/*
+	 * Build a CREATE SEQUENCE command to create the sequence object, and
+	 * add it to the list of things to be done before this CREATE/ALTER
+	 * TABLE.
+	 */
+	seqstmt = makeNode(CreateSeqStmt);
+	seqstmt->for_identity = for_identity;
+	seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	seqstmt->options = seqoptions;
+	/*
+	 * If a sequence data type was specified, add it to the options.  Prepend
+	 * to the list rather than append; in case a user supplied their own AS
+	 * clause, the "redundant options" error will point to their occurrence,
+	 * not our synthetic one.
+	 */
+	if (seqtypid)
+		seqstmt->options = lcons(makeDefElem("as", (Node *) makeTypeNameFromOid(seqtypid, -1), -1),
+								 seqstmt->options);
+
+	/*
+	 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
+	 * by the table's owner.  The current user might be someone else
+	 * (perhaps a superuser, or someone who's only a member of the owning
+	 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
+	 * and sequence have exactly the same owning role.
+	 */
+	if (cxt->rel)
+		seqstmt->ownerId = cxt->rel->rd_rel->relowner;
+	else
+		seqstmt->ownerId = InvalidOid;
+
+	cxt->blist = lappend(cxt->blist, seqstmt);
+
+	/*
+	 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
+	 * as owned by this column, and add it to the list of things to be
+	 * done after this CREATE/ALTER TABLE.
+	 */
+	altseqstmt = makeNode(AlterSeqStmt);
+	altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
+	attnamelist = list_make3(makeString(snamespace),
+							 makeString(cxt->relation->relname),
+							 makeString(column->colname));
+	altseqstmt->options = list_make1(makeDefElem("owned_by",
+												 (Node *) attnamelist, -1));
+	altseqstmt->for_identity = for_identity;
+
+	cxt->alist = lappend(cxt->alist, altseqstmt);
+
+	if (snamespace_p)
+		*snamespace_p = snamespace;
+	if (sname_p)
+		*sname_p = sname;
+}
+
 /*
  * transformColumnDefinition -
  *		transform a single ColumnDef within CREATE TABLE
@@ -367,7 +494,7 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	bool		is_serial;
 	bool		saw_nullable;
 	bool		saw_default;
-	Constraint *constraint;
+	bool		saw_identity;
 	ListCell   *clist;
 
 	cxt->columns = lappend(cxt->columns, column);
@@ -422,83 +549,17 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	/* Special actions for SERIAL pseudo-types */
 	if (is_serial)
 	{
-		Oid			snamespaceid;
 		char	   *snamespace;
 		char	   *sname;
 		char	   *qstring;
 		A_Const    *snamenode;
 		TypeCast   *castnode;
 		FuncCall   *funccallnode;
-		CreateSeqStmt *seqstmt;
-		AlterSeqStmt *altseqstmt;
-		List	   *attnamelist;
+		Constraint *constraint;
 
-		/*
-		 * Determine namespace and name to use for the sequence.
-		 *
-		 * Although we use ChooseRelationName, it's not guaranteed that the
-		 * selected sequence name won't conflict; given sufficiently long
-		 * field names, two different serial columns in the same table could
-		 * be assigned the same sequence name, and we'd not notice since we
-		 * aren't creating the sequence quite yet.  In practice this seems
-		 * quite unlikely to be a problem, especially since few people would
-		 * need two serial columns in one table.
-		 */
-		if (cxt->rel)
-			snamespaceid = RelationGetNamespace(cxt->rel);
-		else
-		{
-			snamespaceid = RangeVarGetCreationNamespace(cxt->relation);
-			RangeVarAdjustRelationPersistence(cxt->relation, snamespaceid);
-		}
-		snamespace = get_namespace_name(snamespaceid);
-		sname = ChooseRelationName(cxt->relation->relname,
-								   column->colname,
-								   "seq",
-								   snamespaceid);
-
-		ereport(DEBUG1,
-				(errmsg("%s will create implicit sequence \"%s\" for serial column \"%s.%s\"",
-						cxt->stmtType, sname,
-						cxt->relation->relname, column->colname)));
-
-		/*
-		 * Build a CREATE SEQUENCE command to create the sequence object, and
-		 * add it to the list of things to be done before this CREATE/ALTER
-		 * TABLE.
-		 */
-		seqstmt = makeNode(CreateSeqStmt);
-		seqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		seqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(column->typeName->typeOid, -1), -1));
-
-		/*
-		 * If this is ALTER ADD COLUMN, make sure the sequence will be owned
-		 * by the table's owner.  The current user might be someone else
-		 * (perhaps a superuser, or someone who's only a member of the owning
-		 * role), but the SEQUENCE OWNED BY mechanisms will bleat unless table
-		 * and sequence have exactly the same owning role.
-		 */
-		if (cxt->rel)
-			seqstmt->ownerId = cxt->rel->rd_rel->relowner;
-		else
-			seqstmt->ownerId = InvalidOid;
-
-		cxt->blist = lappend(cxt->blist, seqstmt);
-
-		/*
-		 * Build an ALTER SEQUENCE ... OWNED BY command to mark the sequence
-		 * as owned by this column, and add it to the list of things to be
-		 * done after this CREATE/ALTER TABLE.
-		 */
-		altseqstmt = makeNode(AlterSeqStmt);
-		altseqstmt->sequence = makeRangeVar(snamespace, sname, -1);
-		attnamelist = list_make3(makeString(snamespace),
-								 makeString(cxt->relation->relname),
-								 makeString(column->colname));
-		altseqstmt->options = list_make1(makeDefElem("owned_by",
-												  (Node *) attnamelist, -1));
-
-		cxt->alist = lappend(cxt->alist, altseqstmt);
+		generateSerialExtraStmts(cxt, column,
+								 column->typeName->typeOid, NIL, false,
+								 &snamespace, &sname);
 
 		/*
 		 * Create appropriate constraints for SERIAL.  We do this in full,
@@ -540,10 +601,11 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 
 	saw_nullable = false;
 	saw_default = false;
+	saw_identity = false;
 
 	foreach(clist, column->constraints)
 	{
-		constraint = castNode(Constraint, lfirst(clist));
+		Constraint *constraint = castNode(Constraint, lfirst(clist));
 
 		switch (constraint->contype)
 		{
@@ -584,6 +646,33 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 				saw_default = true;
 				break;
 
+			case CONSTR_IDENTITY:
+			{
+				Type		ctype;
+				Oid			typeOid;
+
+				ctype = typenameType(cxt->pstate, column->typeName, NULL);
+				typeOid = HeapTupleGetOid(ctype);
+				ReleaseSysCache(ctype);
+
+				if (saw_identity)
+					ereport(ERROR,
+							(errcode(ERRCODE_SYNTAX_ERROR),
+							 errmsg("multiple identity specifications for column \"%s\" of table \"%s\"",
+									column->colname, cxt->relation->relname),
+							 parser_errposition(cxt->pstate,
+												constraint->location)));
+
+				generateSerialExtraStmts(cxt, column,
+										 typeOid, constraint->options, true,
+										 NULL, NULL);
+
+				column->identity = constraint->generated_when;
+				saw_identity = true;
+				column->is_not_null = TRUE;
+				break;
+			}
+
 			case CONSTR_CHECK:
 				cxt->ckconstraints = lappend(cxt->ckconstraints, constraint);
 				break;
@@ -660,6 +749,14 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 					 constraint->contype);
 				break;
 		}
+
+		if (saw_default && saw_identity)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("both default and identity specified for column \"%s\" of table \"%s\"",
+							column->colname, cxt->relation->relname),
+					 parser_errposition(cxt->pstate,
+										constraint->location)));
 	}
 
 	/*
@@ -932,6 +1029,27 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 			def->cooked_default = this_default;
 		}
 
+		/*
+		 * Copy identity if requested
+		 */
+		if (attribute->attidentity &&
+			(table_like_clause->options & CREATE_TABLE_LIKE_IDENTITY))
+		{
+			Oid         seq_relid;
+			List	   *seq_options;
+
+			/*
+			 * find sequence owned by old column; extract sequence parameters;
+			 * build new create sequence command
+			 */
+			seq_relid = getOwnedSequence(RelationGetRelid(relation), attribute->attnum);
+			seq_options = sequence_options(seq_relid);
+			generateSerialExtraStmts(cxt, def,
+									 InvalidOid, seq_options, true,
+									 NULL, NULL);
+			def->identity = attribute->attidentity;
+		}
+
 		/* Likewise, copy storage if requested */
 		if (table_like_clause->options & CREATE_TABLE_LIKE_STORAGE)
 			def->storage = attribute->attstorage;
@@ -2628,6 +2746,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 			case AT_AlterColumnType:
 				{
 					ColumnDef  *def = (ColumnDef *) cmd->def;
+					AttrNumber	attnum;
 
 					/*
 					 * For ALTER COLUMN TYPE, transform the USING clause if
@@ -2640,6 +2759,103 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 										  EXPR_KIND_ALTER_COL_TRANSFORM);
 					}
 
+					/*
+					 * For identity column, create ALTER SEQUENCE command to
+					 * change the data type of the sequence.
+					 */
+					attnum = get_attnum(relid, cmd->name);
+					/* if attribute not found, something will error about it later */
+					if (attnum != InvalidAttrNumber && get_attidentity(relid, attnum))
+					{
+						Oid			seq_relid = getOwnedSequence(relid, attnum);
+						Oid			typeOid = typenameTypeId(pstate, def->typeName);
+						AlterSeqStmt *altseqstmt = makeNode(AlterSeqStmt);
+
+						altseqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															get_rel_name(seq_relid),
+															-1);
+						altseqstmt->options = list_make1(makeDefElem("as", (Node *) makeTypeNameFromOid(typeOid, -1), -1));
+						altseqstmt->for_identity = true;
+						cxt.blist = lappend(cxt.blist, altseqstmt);
+					}
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_AddIdentity:
+				{
+					Constraint  *def = castNode(Constraint, cmd->def);
+					ColumnDef *newdef = makeNode(ColumnDef);
+					AttrNumber	attnum;
+
+					newdef->colname = cmd->name;
+					newdef->identity = def->generated_when;
+					cmd->def = (Node *) newdef;
+
+					attnum = get_attnum(relid, cmd->name);
+					/* if attribute not found, something will error about it later */
+					if (attnum != InvalidAttrNumber)
+						generateSerialExtraStmts(&cxt, newdef,
+												 get_atttype(relid, attnum),
+												 def->options, true,
+												 NULL, NULL);
+
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
+			case AT_SetIdentity:
+				{
+					/*
+					 * Create an ALTER SEQUENCE statement for the internal
+					 * sequence of the identity column.
+					 */
+					ListCell   *lc;
+					List	   *newseqopts = NIL;
+					List	   *newdef = NIL;
+					List	   *seqlist;
+					AttrNumber	attnum;
+
+					/*
+					 * Split options into those handled by ALTER SEQUENCE and
+					 * those for ALTER TABLE proper.
+					 */
+					foreach(lc, castNode(List, cmd->def))
+					{
+						DefElem	   *def = castNode(DefElem, lfirst(lc));
+
+						if (strcmp(def->defname, "generated") == 0)
+							newdef = lappend(newdef, def);
+						else
+							newseqopts = lappend(newseqopts, def);
+					}
+
+					attnum = get_attnum(relid, cmd->name);
+
+					if (attnum)
+					{
+						seqlist = getOwnedSequences(relid, attnum);
+						if (seqlist)
+						{
+							AlterSeqStmt *seqstmt;
+							Oid			seq_relid;
+
+							seqstmt = makeNode(AlterSeqStmt);
+							seq_relid = linitial_oid(seqlist);
+							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+															 get_rel_name(seq_relid), -1);
+							seqstmt->options = newseqopts;
+							seqstmt->for_identity = true;
+							seqstmt->missing_ok = false;
+
+							cxt.alist = lappend(cxt.alist, seqstmt);
+						}
+					}
+					/* If column was not found or was not an identity column, we
+					 * just let the ALTER TABLE command error out later. */
+
+					cmd->def = (Node *) newdef;
 					newcmds = lappend(newcmds, cmd);
 					break;
 				}
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 424be0c768..cb860ec4e5 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -21,6 +21,7 @@
 #include "postgres.h"
 
 #include "access/sysattr.h"
+#include "catalog/dependency.h"
 #include "catalog/pg_type.h"
 #include "commands/trigger.h"
 #include "foreign/fdwapi.h"
@@ -61,6 +62,7 @@ static Query *rewriteRuleAction(Query *parsetree,
 static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static List *rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list);
@@ -709,6 +711,7 @@ adjustJoinTreeList(Query *parsetree, bool removert, int rt_index)
 static List *
 rewriteTargetListIU(List *targetList,
 					CmdType commandType,
+					OverridingKind override,
 					Relation target_relation,
 					int result_rti,
 					List **attrno_list)
@@ -789,6 +792,7 @@ rewriteTargetListIU(List *targetList,
 	for (attrno = 1; attrno <= numattrs; attrno++)
 	{
 		TargetEntry *new_tle = new_tles[attrno - 1];
+		bool	apply_default;
 
 		att_tup = target_relation->rd_att->attrs[attrno - 1];
 
@@ -801,12 +805,51 @@ rewriteTargetListIU(List *targetList,
 		 * it's an INSERT and there's no tlist entry for the column, or the
 		 * tlist entry is a DEFAULT placeholder node.
 		 */
-		if ((new_tle == NULL && commandType == CMD_INSERT) ||
-			(new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)))
+		apply_default = ((new_tle == NULL && commandType == CMD_INSERT) ||
+						 (new_tle && new_tle->expr && IsA(new_tle->expr, SetToDefault)));
+
+		if (commandType == CMD_INSERT)
+		{
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
+			{
+				if (override != OVERRIDING_SYSTEM_VALUE)
+					ereport(ERROR,
+							(errcode(ERRCODE_GENERATED_ALWAYS),
+							 errmsg("cannot insert into column \"%s\"", NameStr(att_tup->attname)),
+							 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+									   NameStr(att_tup->attname)),
+							 errhint("Use OVERRIDING SYSTEM VALUE to override.")));
+			}
+
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_BY_DEFAULT && override == OVERRIDING_USER_VALUE)
+				apply_default = true;
+		}
+
+		if (commandType == CMD_UPDATE)
+		{
+			if (att_tup->attidentity == ATTRIBUTE_IDENTITY_ALWAYS && !apply_default)
+				ereport(ERROR,
+						(errcode(ERRCODE_GENERATED_ALWAYS),
+						 errmsg("column \"%s\" can only be updated to DEFAULT", NameStr(att_tup->attname)),
+						 errdetail("Column \"%s\" is an identity column defined as GENERATED ALWAYS.",
+								   NameStr(att_tup->attname))));
+		}
+
+		if (apply_default)
 		{
 			Node	   *new_expr;
 
-			new_expr = build_column_default(target_relation, attrno);
+			if (att_tup->attidentity)
+			{
+				NextValueExpr *nve = makeNode(NextValueExpr);
+
+				nve->seqid = getOwnedSequence(RelationGetRelid(target_relation), attrno);
+				nve->typeId = att_tup->atttypid;
+
+				new_expr = (Node *) nve;
+			}
+			else
+				new_expr = build_column_default(target_relation, attrno);
 
 			/*
 			 * If there is no default (ie, default is effectively NULL), we
@@ -3232,6 +3275,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				/* Process the main targetlist ... */
 				parsetree->targetList = rewriteTargetListIU(parsetree->targetList,
 													  parsetree->commandType,
+															parsetree->override,
 															rt_entry_relation,
 												   parsetree->resultRelation,
 															&attrnos);
@@ -3244,6 +3288,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->targetList =
 					rewriteTargetListIU(parsetree->targetList,
 										parsetree->commandType,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation, NULL);
 			}
@@ -3254,6 +3299,7 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 				parsetree->onConflict->onConflictSet =
 					rewriteTargetListIU(parsetree->onConflict->onConflictSet,
 										CMD_UPDATE,
+										parsetree->override,
 										rt_entry_relation,
 										parsetree->resultRelation,
 										NULL);
@@ -3263,7 +3309,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
 		{
 			parsetree->targetList =
 				rewriteTargetListIU(parsetree->targetList,
-									parsetree->commandType, rt_entry_relation,
+									parsetree->commandType,
+									parsetree->override,
+									rt_entry_relation,
 									parsetree->resultRelation, NULL);
 			rewriteTargetListUD(parsetree, rt_entry, rt_entry_relation);
 		}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index c2681ced2a..f87551fe79 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5884,6 +5884,14 @@ get_insert_query_def(Query *query, deparse_context *context)
 	if (query->targetList)
 		appendStringInfoString(buf, ") ");
 
+	if (query->override)
+	{
+		if (query->override == OVERRIDING_SYSTEM_VALUE)
+			appendStringInfoString(buf, "OVERRIDING SYSTEM VALUE ");
+		else if (query->override == OVERRIDING_USER_VALUE)
+			appendStringInfoString(buf, "OVERRIDING USER VALUE ");
+	}
+
 	if (select_rte)
 	{
 		/* Add the SELECT */
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index b891f388e5..0667ef5a81 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -837,6 +837,38 @@ get_attnum(Oid relid, const char *attname)
 }
 
 /*
+ * get_attidentity
+ *
+ *		Given the relation id and the attribute name,
+ *		return the "attidentity" field from the attribute relation.
+ *
+ *		Returns '\0' if not found.
+ *
+ *		Since no identity is represented by '\0', this can also be used as a
+ *		Boolean test.
+ */
+char
+get_attidentity(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+		char			result;
+
+		result = att_tup->attidentity;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return '\0';
+}
+
+/*
  * get_atttype
  *
  *		Given the relation OID and the attribute number with the relation,
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index bc220989a1..24ffea8f40 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -3268,6 +3268,7 @@ RelationBuildLocalRelation(const char *relname,
 	has_not_null = false;
 	for (i = 0; i < natts; i++)
 	{
+		rel->rd_att->attrs[i]->attidentity = tupDesc->attrs[i]->attidentity;
 		rel->rd_att->attrs[i]->attnotnull = tupDesc->attrs[i]->attnotnull;
 		has_not_null |= tupDesc->attrs[i]->attnotnull;
 	}
diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt
index b6e0e987a8..4f35471762 100644
--- a/src/backend/utils/errcodes.txt
+++ b/src/backend/utils/errcodes.txt
@@ -327,6 +327,7 @@ Section: Class 42 - Syntax Error or Access Rule Violation
 42P21    E    ERRCODE_COLLATION_MISMATCH                                     collation_mismatch
 42P22    E    ERRCODE_INDETERMINATE_COLLATION                                indeterminate_collation
 42809    E    ERRCODE_WRONG_OBJECT_TYPE                                      wrong_object_type
+428C9    E    ERRCODE_GENERATED_ALWAYS                                       generated_always
 
 # Note: for ERRCODE purposes, we divide namable objects into these categories:
 # databases, schemas, prepared statements, cursors, tables, columns,
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 262f5539bc..f9c93cc9a0 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -43,6 +43,7 @@
 #include "access/sysattr.h"
 #include "access/transam.h"
 #include "catalog/pg_am.h"
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_cast.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_default_acl.h"
@@ -1925,6 +1926,9 @@ dumpTableData_insert(Archive *fout, void *dcontext)
 						appendPQExpBufferStr(insertStmt, ") ");
 					}
 
+					if (tbinfo->needs_override)
+						appendPQExpBufferStr(insertStmt, "OVERRIDING SYSTEM VALUE ");
+
 					appendPQExpBufferStr(insertStmt, "VALUES (");
 				}
 			}
@@ -5451,6 +5455,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_toastreloptions;
 	int			i_reloftype;
 	int			i_relpages;
+	int			i_is_identity_sequence;
 	int			i_changed_acl;
 
 	/* Make sure we are in proper schema */
@@ -5528,6 +5533,7 @@ getTables(Archive *fout, int *numTables)
 						  "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text "
 						  "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "
 						  "tc.reloptions AS toast_reloptions, "
+						  "c.relkind = '%c' AND EXISTS (SELECT 1 FROM pg_depend WHERE classid = 'pg_class'::regclass AND objid = c.oid AND objsubid = 0 AND refclassid = 'pg_class'::regclass AND deptype = 'i') AS is_identity_sequence, "
 						  "EXISTS (SELECT 1 FROM pg_attribute at LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
 						  "AND pip.classoid = 'pg_class'::regclass "
@@ -5544,7 +5550,7 @@ getTables(Archive *fout, int *numTables)
 						  "(c.relkind = '%c' AND "
 						  "d.classid = c.tableoid AND d.objid = c.oid AND "
 						  "d.objsubid = 0 AND "
-						  "d.refclassid = c.tableoid AND d.deptype = 'a') "
+						  "d.refclassid = c.tableoid AND d.deptype IN ('a', 'i')) "
 					   "LEFT JOIN pg_class tc ON (c.reltoastrelid = tc.oid) "
 						  "LEFT JOIN pg_init_privs pip ON "
 						  "(c.oid = pip.objoid "
@@ -5557,6 +5563,7 @@ getTables(Archive *fout, int *numTables)
 						  initacl_subquery->data,
 						  initracl_subquery->data,
 						  username_subquery,
+						  RELKIND_SEQUENCE,
 						  attacl_subquery->data,
 						  attracl_subquery->data,
 						  attinitacl_subquery->data,
@@ -5979,6 +5986,7 @@ getTables(Archive *fout, int *numTables)
 	i_checkoption = PQfnumber(res, "checkoption");
 	i_toastreloptions = PQfnumber(res, "toast_reloptions");
 	i_reloftype = PQfnumber(res, "reloftype");
+	i_is_identity_sequence = PQfnumber(res, "is_identity_sequence");
 	i_changed_acl = PQfnumber(res, "changed_acl");
 
 	if (dopt->lockWaitTimeout)
@@ -6079,6 +6087,8 @@ getTables(Archive *fout, int *numTables)
 		tblinfo[i].dummy_view = false;	/* might get set during sort */
 		tblinfo[i].postponed_def = false;		/* might get set during sort */
 
+		tblinfo[i].is_identity_sequence = (strcmp(PQgetvalue(res, i, i_is_identity_sequence), "t") == 0);
+
 		/*
 		 * Read-lock target tables to make sure they aren't DROPPED or altered
 		 * in schema before we get around to dumping them.
@@ -7735,6 +7745,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	int			i_typstorage;
 	int			i_attnotnull;
 	int			i_atthasdef;
+	int			i_attidentity;
 	int			i_attisdropped;
 	int			i_attlen;
 	int			i_attalign;
@@ -7777,7 +7788,34 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 
 		resetPQExpBuffer(q);
 
-		if (fout->remoteVersion >= 90200)
+		if (fout->remoteVersion >= 100000)
+		{
+			/*
+			 * attidentity is new in version 10.
+			 */
+			appendPQExpBuffer(q, "SELECT a.attnum, a.attname, a.atttypmod, "
+							  "a.attstattarget, a.attstorage, t.typstorage, "
+							  "a.attnotnull, a.atthasdef, a.attisdropped, "
+							  "a.attlen, a.attalign, a.attislocal, "
+				  "pg_catalog.format_type(t.oid,a.atttypmod) AS atttypname, "
+						"array_to_string(a.attoptions, ', ') AS attoptions, "
+							  "CASE WHEN a.attcollation <> t.typcollation "
+						   "THEN a.attcollation ELSE 0 END AS attcollation, "
+							  "a.attidentity, "
+							  "pg_catalog.array_to_string(ARRAY("
+							  "SELECT pg_catalog.quote_ident(option_name) || "
+							  "' ' || pg_catalog.quote_literal(option_value) "
+						"FROM pg_catalog.pg_options_to_table(attfdwoptions) "
+							  "ORDER BY option_name"
+							  "), E',\n    ') AS attfdwoptions "
+			 "FROM pg_catalog.pg_attribute a LEFT JOIN pg_catalog.pg_type t "
+							  "ON a.atttypid = t.oid "
+							  "WHERE a.attrelid = '%u'::pg_catalog.oid "
+							  "AND a.attnum > 0::pg_catalog.int2 "
+							  "ORDER BY a.attrelid, a.attnum",
+							  tbinfo->dobj.catId.oid);
+		}
+		else if (fout->remoteVersion >= 90200)
 		{
 			/*
 			 * attfdwoptions is new in 9.2.
@@ -7876,6 +7914,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		i_typstorage = PQfnumber(res, "typstorage");
 		i_attnotnull = PQfnumber(res, "attnotnull");
 		i_atthasdef = PQfnumber(res, "atthasdef");
+		i_attidentity = PQfnumber(res, "attidentity");
 		i_attisdropped = PQfnumber(res, "attisdropped");
 		i_attlen = PQfnumber(res, "attlen");
 		i_attalign = PQfnumber(res, "attalign");
@@ -7891,6 +7930,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		tbinfo->attstattarget = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attstorage = (char *) pg_malloc(ntups * sizeof(char));
 		tbinfo->typstorage = (char *) pg_malloc(ntups * sizeof(char));
+		tbinfo->attidentity = (char *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attisdropped = (bool *) pg_malloc(ntups * sizeof(bool));
 		tbinfo->attlen = (int *) pg_malloc(ntups * sizeof(int));
 		tbinfo->attalign = (char *) pg_malloc(ntups * sizeof(char));
@@ -7915,6 +7955,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			tbinfo->attstattarget[j] = atoi(PQgetvalue(res, j, i_attstattarget));
 			tbinfo->attstorage[j] = *(PQgetvalue(res, j, i_attstorage));
 			tbinfo->typstorage[j] = *(PQgetvalue(res, j, i_typstorage));
+			tbinfo->attidentity[j] = *(PQgetvalue(res, j, i_attidentity));
+			tbinfo->needs_override = tbinfo->needs_override || (tbinfo->attidentity[j] == ATTRIBUTE_IDENTITY_ALWAYS);
 			tbinfo->attisdropped[j] = (PQgetvalue(res, j, i_attisdropped)[0] == 't');
 			tbinfo->attlen[j] = atoi(PQgetvalue(res, j, i_attlen));
 			tbinfo->attalign[j] = *(PQgetvalue(res, j, i_attalign));
@@ -16307,10 +16349,13 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	/*
 	 * DROP must be fully qualified in case same name appears in pg_catalog
 	 */
-	appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
-					  fmtId(tbinfo->dobj.namespace->dobj.name));
-	appendPQExpBuffer(delqry, "%s;\n",
-					  fmtId(tbinfo->dobj.name));
+	if (!tbinfo->is_identity_sequence)
+	{
+		appendPQExpBuffer(delqry, "DROP SEQUENCE %s.",
+						  fmtId(tbinfo->dobj.namespace->dobj.name));
+		appendPQExpBuffer(delqry, "%s;\n",
+						  fmtId(tbinfo->dobj.name));
+	}
 
 	resetPQExpBuffer(query);
 
@@ -16322,11 +16367,30 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 												tbinfo->dobj.catId.oid);
 	}
 
-	appendPQExpBuffer(query,
-					  "CREATE SEQUENCE %s\n",
-					  fmtId(tbinfo->dobj.name));
+	if (tbinfo->is_identity_sequence)
+	{
+		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
+
+		appendPQExpBuffer(query,
+						  "ALTER TABLE %s ",
+						  fmtId(owning_tab->dobj.name));
+		appendPQExpBuffer(query,
+						  "ALTER COLUMN %s ADD GENERATED ",
+						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
+		if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_ALWAYS)
+			appendPQExpBuffer(query, "ALWAYS");
+		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
+			appendPQExpBuffer(query, "BY DEFAULT");
+		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+						  fmtId(tbinfo->dobj.name));
+	}
+	else
+		appendPQExpBuffer(query,
+						  "CREATE SEQUENCE %s\n",
+						  fmtId(tbinfo->dobj.name));
 
-	if (strcmp(seqtype, "bigint") != 0)
+	if (strcmp(seqtype, "bigint") != 0 &&
+		!tbinfo->is_identity_sequence)
 		appendPQExpBuffer(query, "    AS %s\n", seqtype);
 
 	if (fout->remoteVersion >= 80400)
@@ -16348,7 +16412,10 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 					  "    CACHE %s%s",
 					  cache, (cycled ? "\n    CYCLE" : ""));
 
-	appendPQExpBufferStr(query, ";\n");
+	if (tbinfo->is_identity_sequence)
+		appendPQExpBufferStr(query, "\n);\n");
+	else
+		appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
@@ -16381,7 +16448,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	 * We need not schema-qualify the table reference because both sequence
 	 * and table must be in the same schema.
 	 */
-	if (OidIsValid(tbinfo->owning_tab))
+	if (OidIsValid(tbinfo->owning_tab) && !tbinfo->is_identity_sequence)
 	{
 		TableInfo  *owning_tab = findTableByOid(tbinfo->owning_tab);
 
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index cb22f63bd6..61097e6d99 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -288,6 +288,7 @@ typedef struct _tableInfo
 	/* these two are set only if table is a sequence owned by a column: */
 	Oid			owning_tab;		/* OID of table owning sequence */
 	int			owning_col;		/* attr # of column owning sequence */
+	bool		is_identity_sequence;
 	int			relpages;		/* table's size in pages (from pg_class) */
 
 	bool		interesting;	/* true if need to collect more data */
@@ -306,6 +307,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	char	   *attidentity;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
 	char	   *attalign;		/* attribute align, used by binary_upgrade */
 	bool	   *attislocal;		/* true if attr has local definition */
@@ -317,6 +319,7 @@ typedef struct _tableInfo
 	struct _attrDefInfo **attrdefs;		/* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
 	char	   *partkeydef;		/* partition key definition */
+	bool		needs_override;	/* has GENERATED ALWAYS AS IDENTITY */
 
 	/*
 	 * Stuff computed only for dumpable tables.
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index b0f3e5e347..d70845bba6 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -14,6 +14,7 @@
 
 #include <ctype.h>
 
+#include "catalog/pg_attribute.h"
 #include "catalog/pg_class.h"
 #include "catalog/pg_default_acl.h"
 #include "fe_utils/string_utils.h"
@@ -1592,6 +1593,10 @@ describeOneTableDetails(const char *schemaname,
 							 "   WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation");
 	else
 		appendPQExpBufferStr(&buf, "\n  NULL AS attcollation");
+	if (pset.sversion >= 100000)
+		appendPQExpBufferStr(&buf, ", a.attidentity");
+	else
+		appendPQExpBufferStr(&buf, ", ''::\"char\" AS attidentity");
 	if (tableinfo.relkind == RELKIND_INDEX)
 		appendPQExpBufferStr(&buf, ",\n  pg_catalog.pg_get_indexdef(a.attrelid, a.attnum, TRUE) AS indexdef");
 	else
@@ -1778,12 +1783,24 @@ describeOneTableDetails(const char *schemaname,
 		/* Collation, Nullable, Default */
 		if (show_column_details)
 		{
+			char   *identity;
+			char   *default_str = "";
+
 			printTableAddCell(&cont, PQgetvalue(res, i, 5), false, false);
 
 			printTableAddCell(&cont, strcmp(PQgetvalue(res, i, 3), "t") == 0 ? "not null" : "", false, false);
 
-			/* (note: above we cut off the 'default' string at 128) */
-			printTableAddCell(&cont, PQgetvalue(res, i, 2), false, false);
+			identity = PQgetvalue(res, i, 6);
+
+			if (!identity[0])
+				/* (note: above we cut off the 'default' string at 128) */
+				default_str = PQgetvalue(res, i, 2);
+			else if (identity[0] == ATTRIBUTE_IDENTITY_ALWAYS)
+				default_str = "generated always as identity";
+			else if (identity[0] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
+				default_str = "generated by default as identity";
+
+			printTableAddCell(&cont, default_str, false, false);
 		}
 
 		/* Value: for sequences only */
@@ -1792,16 +1809,16 @@ describeOneTableDetails(const char *schemaname,
 
 		/* Expression for index column */
 		if (tableinfo.relkind == RELKIND_INDEX)
-			printTableAddCell(&cont, PQgetvalue(res, i, 6), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
 
 		/* FDW options for foreign table column, only for 9.2 or later */
 		if (tableinfo.relkind == RELKIND_FOREIGN_TABLE && pset.sversion >= 90200)
-			printTableAddCell(&cont, PQgetvalue(res, i, 7), false, false);
+			printTableAddCell(&cont, PQgetvalue(res, i, 8), false, false);
 
 		/* Storage and Description */
 		if (verbose)
 		{
-			int			firstvcol = 8;
+			int			firstvcol = 9;
 			char	   *storage = PQgetvalue(res, i, firstvcol);
 
 			/* these strings are literal in our syntax, so not translated. */
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index dc2794d48a..b2a70df200 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -1895,7 +1895,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> */
 	else if (Matches6("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny) ||
 			 Matches5("ALTER", "TABLE", MatchAny, "ALTER", MatchAny))
-		COMPLETE_WITH_LIST4("TYPE", "SET", "RESET", "DROP");
+		COMPLETE_WITH_LIST5("TYPE", "SET", "RESET", "ADD", "DROP");
 	/* ALTER TABLE ALTER [COLUMN] <foo> SET */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "SET") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "SET"))
@@ -1911,7 +1911,7 @@ psql_completion(const char *text, int start, int end)
 	/* ALTER TABLE ALTER [COLUMN] <foo> DROP */
 	else if (Matches7("ALTER", "TABLE", MatchAny, "ALTER", "COLUMN", MatchAny, "DROP") ||
 			 Matches6("ALTER", "TABLE", MatchAny, "ALTER", MatchAny, "DROP"))
-		COMPLETE_WITH_LIST2("DEFAULT", "NOT NULL");
+		COMPLETE_WITH_LIST3("DEFAULT", "IDENTITY", "NOT NULL");
 	else if (Matches4("ALTER", "TABLE", MatchAny, "CLUSTER"))
 		COMPLETE_WITH_CONST("ON");
 	else if (Matches5("ALTER", "TABLE", MatchAny, "CLUSTER", "ON"))
@@ -2920,17 +2920,25 @@ psql_completion(const char *text, int start, int end)
 
 	/*
 	 * Complete INSERT INTO <table> with "(" or "VALUES" or "SELECT" or
-	 * "TABLE" or "DEFAULT VALUES"
+	 * "TABLE" or "DEFAULT VALUES" or "OVERRIDING"
 	 */
 	else if (TailMatches3("INSERT", "INTO", MatchAny))
-		COMPLETE_WITH_LIST5("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES");
+		COMPLETE_WITH_LIST6("(", "DEFAULT VALUES", "SELECT", "TABLE", "VALUES", "OVERRIDING");
 
 	/*
 	 * Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" or
-	 * "TABLE"
+	 * "TABLE" or "OVERRIDING"
 	 */
 	else if (TailMatches4("INSERT", "INTO", MatchAny, MatchAny) &&
 			 ends_with(prev_wd, ')'))
+		COMPLETE_WITH_LIST4("SELECT", "TABLE", "VALUES", "OVERRIDING");
+
+	/* Complete OVERRIDING */
+	else if (TailMatches1("OVERRIDING"))
+		COMPLETE_WITH_LIST2("SYSTEM VALUE", "USER VALUE");
+
+	/* Complete after OVERRIDING clause */
+	else if (TailMatches3("OVERRIDING", MatchAny, "VALUE"))
 		COMPLETE_WITH_LIST3("SELECT", "TABLE", "VALUES");
 
 	/* Insert an open parenthesis after "VALUES" */
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 9effbce2f1..33361ffce9 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -238,11 +238,9 @@ extern long changeDependencyFor(Oid classId, Oid objectId,
 
 extern Oid	getExtensionOfObject(Oid classId, Oid objectId);
 
-extern bool sequenceIsOwned(Oid seqId, Oid *tableId, int32 *colId);
-
-extern void markSequenceUnowned(Oid seqId);
-
-extern List *getOwnedSequences(Oid relid);
+extern bool sequenceIsOwned(Oid seqId, char deptype, Oid *tableId, int32 *colId);
+extern List *getOwnedSequences(Oid relid, AttrNumber attnum);
+extern Oid getOwnedSequence(Oid relid, AttrNumber attnum);
 
 extern Oid	get_constraint_index(Oid constraintId);
 
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index e861f4c589..753d45f2d1 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -133,6 +133,9 @@ CATALOG(pg_attribute,1249) BKI_BOOTSTRAP BKI_WITHOUT_OIDS BKI_ROWTYPE_OID(75) BK
 	/* Has DEFAULT value or not */
 	bool		atthasdef;
 
+	/* One of the ATTRIBUTE_IDENTITY_* constants below, or '\0' */
+	char		attidentity;
+
 	/* Is dropped (ie, logically invisible) or not */
 	bool		attisdropped;
 
@@ -188,7 +191,7 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
-#define Natts_pg_attribute				21
+#define Natts_pg_attribute				22
 #define Anum_pg_attribute_attrelid		1
 #define Anum_pg_attribute_attname		2
 #define Anum_pg_attribute_atttypid		3
@@ -203,13 +206,14 @@ typedef FormData_pg_attribute *Form_pg_attribute;
 #define Anum_pg_attribute_attalign		12
 #define Anum_pg_attribute_attnotnull	13
 #define Anum_pg_attribute_atthasdef		14
-#define Anum_pg_attribute_attisdropped	15
-#define Anum_pg_attribute_attislocal	16
-#define Anum_pg_attribute_attinhcount	17
-#define Anum_pg_attribute_attcollation	18
-#define Anum_pg_attribute_attacl		19
-#define Anum_pg_attribute_attoptions	20
-#define Anum_pg_attribute_attfdwoptions 21
+#define Anum_pg_attribute_attidentity	15
+#define Anum_pg_attribute_attisdropped	16
+#define Anum_pg_attribute_attislocal	17
+#define Anum_pg_attribute_attinhcount	18
+#define Anum_pg_attribute_attcollation	19
+#define Anum_pg_attribute_attacl		20
+#define Anum_pg_attribute_attoptions	21
+#define Anum_pg_attribute_attfdwoptions 22
 
 
 /* ----------------
@@ -220,4 +224,8 @@ typedef FormData_pg_attribute *Form_pg_attribute;
  * ----------------
  */
 
+
+#define		  ATTRIBUTE_IDENTITY_ALWAYS		'a'
+#define		  ATTRIBUTE_IDENTITY_BY_DEFAULT 'd'
+
 #endif   /* PG_ATTRIBUTE_H */
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index d1d493ee05..5a288830e8 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -149,7 +149,7 @@ typedef FormData_pg_class *Form_pg_class;
  */
 DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 21 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
 DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 29 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
diff --git a/src/include/commands/sequence.h b/src/include/commands/sequence.h
index 49a77c42fc..304586e48e 100644
--- a/src/include/commands/sequence.h
+++ b/src/include/commands/sequence.h
@@ -51,7 +51,9 @@ typedef struct xl_seq_rec
 	/* SEQUENCE TUPLE DATA FOLLOWS AT THE END */
 } xl_seq_rec;
 
+extern int64 nextval_internal(Oid relid, bool check_permissions);
 extern Datum nextval(PG_FUNCTION_ARGS);
+extern List *sequence_options(Oid relid);
 
 extern ObjectAddress DefineSequence(ParseState *pstate, CreateSeqStmt *stmt);
 extern ObjectAddress AlterSequence(ParseState *pstate, AlterSeqStmt *stmt);
diff --git a/src/include/executor/execExpr.h b/src/include/executor/execExpr.h
index a665388232..8d32c6fb80 100644
--- a/src/include/executor/execExpr.h
+++ b/src/include/executor/execExpr.h
@@ -144,6 +144,7 @@ typedef enum ExprEvalOp
 	EEOP_NULLIF,
 	EEOP_SQLVALUEFUNCTION,
 	EEOP_CURRENTOFEXPR,
+	EEOP_NEXTVALUEEXPR,
 	EEOP_ARRAYEXPR,
 	EEOP_ARRAYCOERCE,
 	EEOP_ROW,
@@ -361,6 +362,12 @@ typedef struct ExprEvalStep
 			SQLValueFunction *svf;
 		}			sqlvaluefunction;
 
+		/* for EEOP_NEXTVALUEXPR */
+		struct
+		{
+			Oid			seqid;
+		}			nextvalueexpr;
+
 		/* for EEOP_ARRAYEXPR */
 		struct
 		{
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 963ce45ae3..672c5abad7 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -188,6 +188,7 @@ typedef enum NodeTag
 	T_FromExpr,
 	T_OnConflictExpr,
 	T_IntoClause,
+	T_NextValueExpr,
 
 	/*
 	 * TAGS FOR EXPRESSION STATE NODES (execnodes.h)
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 3a71dd5b37..ed95be4a8f 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -27,6 +27,13 @@
 #include "nodes/primnodes.h"
 #include "nodes/value.h"
 
+typedef enum OverridingKind
+{
+	OVERRIDING_NOT_SET = 0,
+	OVERRIDING_USER_VALUE,
+	OVERRIDING_SYSTEM_VALUE
+} OverridingKind;
+
 /* Possible sources of a Query */
 typedef enum QuerySource
 {
@@ -130,6 +137,8 @@ typedef struct Query
 
 	List	   *targetList;		/* target list (of TargetEntry) */
 
+	OverridingKind override;	/* OVERRIDING clause */
+
 	OnConflictExpr *onConflict; /* ON CONFLICT DO [NOTHING | UPDATE] */
 
 	List	   *returningList;	/* return-values list (of TargetEntry) */
@@ -637,6 +646,7 @@ typedef struct ColumnDef
 	char		storage;		/* attstorage setting, or 0 for default */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
 	Node	   *cooked_default; /* default value (transformed expr tree) */
+	char		identity;		/* attidentity setting */
 	CollateClause *collClause;	/* untransformed COLLATE spec, if any */
 	Oid			collOid;		/* collation OID (InvalidOid if not set) */
 	List	   *constraints;	/* other constraints on column */
@@ -658,9 +668,10 @@ typedef enum TableLikeOption
 {
 	CREATE_TABLE_LIKE_DEFAULTS = 1 << 0,
 	CREATE_TABLE_LIKE_CONSTRAINTS = 1 << 1,
-	CREATE_TABLE_LIKE_INDEXES = 1 << 2,
-	CREATE_TABLE_LIKE_STORAGE = 1 << 3,
-	CREATE_TABLE_LIKE_COMMENTS = 1 << 4,
+	CREATE_TABLE_LIKE_IDENTITY = 1 << 2,
+	CREATE_TABLE_LIKE_INDEXES = 1 << 3,
+	CREATE_TABLE_LIKE_STORAGE = 1 << 4,
+	CREATE_TABLE_LIKE_COMMENTS = 1 << 5,
 	CREATE_TABLE_LIKE_ALL = PG_INT32_MAX
 } TableLikeOption;
 
@@ -1399,6 +1410,7 @@ typedef struct InsertStmt
 	OnConflictClause *onConflictClause; /* ON CONFLICT clause */
 	List	   *returningList;	/* list of expressions to return */
 	WithClause *withClause;		/* WITH clause */
+	OverridingKind override;	/* OVERRIDING clause */
 } InsertStmt;
 
 /* ----------------------
@@ -1709,7 +1721,10 @@ typedef enum AlterTableType
 	AT_NoForceRowSecurity,		/* NO FORCE ROW SECURITY */
 	AT_GenericOptions,			/* OPTIONS (...) */
 	AT_AttachPartition,			/* ATTACH PARTITION */
-	AT_DetachPartition			/* DETACH PARTITION */
+	AT_DetachPartition,			/* DETACH PARTITION */
+	AT_AddIdentity,				/* ADD IDENTITY */
+	AT_SetIdentity,				/* SET identity column options */
+	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
 
 typedef struct ReplicaIdentityStmt
@@ -1996,6 +2011,7 @@ typedef enum ConstrType			/* types of constraints */
 								 * expect it */
 	CONSTR_NOTNULL,
 	CONSTR_DEFAULT,
+	CONSTR_IDENTITY,
 	CONSTR_CHECK,
 	CONSTR_PRIMARY,
 	CONSTR_UNIQUE,
@@ -2034,6 +2050,7 @@ typedef struct Constraint
 	bool		is_no_inherit;	/* is constraint non-inheritable? */
 	Node	   *raw_expr;		/* expr, as untransformed parse tree */
 	char	   *cooked_expr;	/* expr, as nodeToString representation */
+	char		generated_when;
 
 	/* Fields used for unique constraints (UNIQUE and PRIMARY KEY): */
 	List	   *keys;			/* String nodes naming referenced column(s) */
@@ -2412,6 +2429,7 @@ typedef struct CreateSeqStmt
 	RangeVar   *sequence;		/* the sequence to create */
 	List	   *options;
 	Oid			ownerId;		/* ID of owner, or InvalidOid for default */
+	bool		for_identity;
 	bool		if_not_exists;	/* just do nothing if it already exists? */
 } CreateSeqStmt;
 
@@ -2420,6 +2438,7 @@ typedef struct AlterSeqStmt
 	NodeTag		type;
 	RangeVar   *sequence;		/* the sequence to alter */
 	List	   *options;
+	bool		for_identity;
 	bool		missing_ok;		/* skip error if a role is missing? */
 } AlterSeqStmt;
 
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index d57b4fab3d..b87fe84545 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1292,6 +1292,20 @@ typedef struct InferenceElem
 	Oid			inferopclass;	/* OID of att opclass, or InvalidOid */
 } InferenceElem;
 
+/*
+ * NextValueExpr - get next value from sequence
+ *
+ * This has the same effect as calling the nextval() function, but it does not
+ * check permissions on the sequence.  This is used for identity columns,
+ * where the sequence is an implicit dependency without its own permissions.
+ */
+typedef struct NextValueExpr
+{
+	Expr		xpr;
+	Oid			seqid;
+	Oid			typeId;
+} NextValueExpr;
+
 /*--------------------
  * TargetEntry -
  *	   a target entry (used in query target lists)
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index cd21a789d5..37542aaee4 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -174,6 +174,7 @@ PG_KEYWORD("from", FROM, RESERVED_KEYWORD)
 PG_KEYWORD("full", FULL, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("function", FUNCTION, UNRESERVED_KEYWORD)
 PG_KEYWORD("functions", FUNCTIONS, UNRESERVED_KEYWORD)
+PG_KEYWORD("generated", GENERATED, UNRESERVED_KEYWORD)
 PG_KEYWORD("global", GLOBAL, UNRESERVED_KEYWORD)
 PG_KEYWORD("grant", GRANT, RESERVED_KEYWORD)
 PG_KEYWORD("granted", GRANTED, UNRESERVED_KEYWORD)
@@ -287,6 +288,7 @@ PG_KEYWORD("outer", OUTER_P, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("over", OVER, UNRESERVED_KEYWORD)
 PG_KEYWORD("overlaps", OVERLAPS, TYPE_FUNC_NAME_KEYWORD)
 PG_KEYWORD("overlay", OVERLAY, COL_NAME_KEYWORD)
+PG_KEYWORD("overriding", OVERRIDING, UNRESERVED_KEYWORD)
 PG_KEYWORD("owned", OWNED, UNRESERVED_KEYWORD)
 PG_KEYWORD("owner", OWNER, UNRESERVED_KEYWORD)
 PG_KEYWORD("parallel", PARALLEL, UNRESERVED_KEYWORD)
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index b6d1fca2fa..88629d99aa 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -64,6 +64,7 @@ extern Oid get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype,
 extern char *get_attname(Oid relid, AttrNumber attnum);
 extern char *get_relid_attribute_name(Oid relid, AttrNumber attnum);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
+extern char	get_attidentity(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern int32 get_atttypmod(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
diff --git a/src/test/regress/expected/create_table_like.out b/src/test/regress/expected/create_table_like.out
index a25b221703..3f405c94ce 100644
--- a/src/test/regress/expected/create_table_like.out
+++ b/src/test/regress/expected/create_table_like.out
@@ -66,6 +66,53 @@ SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y
 (2 rows)
 
 DROP TABLE inhg;
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+                     Table "public.test_like_id_1"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+ a | b  
+---+----
+ 1 | b1
+(1 row)
+
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+           Table "public.test_like_id_2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ a      | integer |           | not null | 
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, b2).
+SELECT * FROM test_like_id_2;  -- identity was not copied
+ a | b 
+---+---
+(0 rows)
+
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+                     Table "public.test_like_id_3"
+ Column |  Type   | Collation | Nullable |           Default            
+--------+---------+-----------+----------+------------------------------
+ a      | integer |           | not null | generated always as identity
+ b      | text    |           |          | 
+
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+ a | b  
+---+----
+ 1 | b3
+(1 row)
+
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
new file mode 100644
index 0000000000..88b56dad93
--- /dev/null
+++ b/src/test/regress/expected/identity.out
@@ -0,0 +1,322 @@
+-- sanity check of system catalog
+SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN ('', 'a', 'd');
+ attrelid | attname | attidentity 
+----------+---------+-------------
+(0 rows)
+
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  column "a" of relation "itest3" is already an identity column
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+ table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
+------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
+ itest1     | a           |                | NO          | YES         | BY DEFAULT          | 1              | 1                  | 2147483647          | 1                | NO
+ itest1     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest2     | a           |                | NO          | YES         | ALWAYS              | 1              | 1                  | 9223372036854775807 | 1                | NO
+ itest2     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+ itest3     | a           |                | NO          | YES         | BY DEFAULT          | 7              | 5                  | 32767               | 1                | NO
+ itest3     | b           |                | YES         | NO          |                     |                |                    |                     |                  | NO
+(6 rows)
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+ sequence_name 
+---------------
+(0 rows)
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ERROR:  column "a" of relation "itest4" is an identity column
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ERROR:  column "a" of relation "itest4" is already an identity column
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ERROR:  identity column type must be smallint, integer, or bigint
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+ERROR:  identity column type must be smallint, integer, or bigint
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+ERROR:  multiple identity specifications for column "a" of table "itest_err_2"
+LINE 1: ...E itest_err_2 (a int generated always as identity generated ...
+                                                             ^
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_3"
+LINE 1: CREATE TABLE itest_err_3 (a int default 5 generated by defau...
+                                                  ^
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+ERROR:  both default and identity specified for column "a" of table "itest_err_4"
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest1;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest2;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itest3;
+ a  | b 
+----+---
+  7 | 
+ 12 | 
+(2 rows)
+
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+-- OVERRIDING tests
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+SELECT * FROM itest1;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+(3 rows)
+
+-- UPDATE tests
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+  a  |  b  
+-----+-----
+  10 | xyz
+   3 | xyz
+ 101 | 
+   4 | 
+(4 rows)
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+ERROR:  column "a" can only be updated to DEFAULT
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+ a  |  b  
+----+-----
+  1 | 
+ 10 | xyz
+  3 | 
+(3 rows)
+
+-- DROP IDENTITY tests
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ERROR:  column "a" of relation "itest4" is not an identity column
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY IF EXISTS;  -- noop
+NOTICE:  column "a" of relation "itest4" is not an identity column, skipping
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ERROR:  null value in column "a" violates not-null constraint
+DETAIL:  Failing row contains (null, ).
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+   | 
+(3 rows)
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+ERROR:  relation "itest4_a_seq" does not exist
+LINE 1: SELECT sequence_name FROM itest4_a_seq;
+                                  ^
+-- test views
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+SELECT * FROM itestv10;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+SELECT * FROM itestv11;
+ a | b 
+---+---
+ 1 | 
+ 2 | 
+(2 rows)
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv10;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 10 | xyz
+  3 | xyz
+(4 rows)
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+ERROR:  cannot insert into column "a"
+DETAIL:  Column "a" is an identity column defined as GENERATED ALWAYS.
+HINT:  Use OVERRIDING SYSTEM VALUE to override.
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+SELECT * FROM itestv11;
+ a  |  b  
+----+-----
+  1 | 
+  2 | 
+ 11 | xyz
+(3 rows)
+
+-- various ALTER COLUMN tests
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+ERROR:  column "a" of relation "itest1" is an identity column
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ERROR:  column "a" of relation "itest5" already has a default value
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+ seqtypid 
+----------
+ integer
+(1 row)
+
+\d itest3
+                           Table "public.itest3"
+ Column |  Type   | Collation | Nullable |             Default              
+--------+---------+-----------+----------+----------------------------------
+ a      | integer |           | not null | generated by default as identity
+ b      | text    |           |          | 
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+ERROR:  identity column type must be smallint, integer, or bigint
+-- ALTER COLUMN ... SET
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+  a  | b 
+-----+---
+   1 | 
+ 100 | 
+ 102 | 
+(3 rows)
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+ table_name | column_name | is_identity | identity_generation 
+------------+-------------+-------------+---------------------
+ itest6     | a           | YES         | BY DEFAULT
+ itest6     | b           | NO          | 
+(2 rows)
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+ERROR:  column "b" of relation "itest6" is not an identity column
+-- prohibited direct modification of sequence
+ALTER SEQUENCE itest6_a_seq OWNED BY NONE;
+ERROR:  cannot change ownership of identity sequence
+DETAIL:  Sequence "itest6_a_seq" is linked to table "itest6".
+-- inheritance
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+ a 
+---
+ 1
+(1 row)
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+NOTICE:  merging column "a" with inherited definition
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+ a 
+---
+ 1
+(1 row)
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+ERROR:  cannot recursively add identity column to table that has child tables
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+ table_name | column_name | is_nullable | is_identity | identity_generation 
+------------+-------------+-------------+-------------+---------------------
+ itest7     | a           | NO          | YES         | ALWAYS
+ itest7a    | a           | NO          | NO          | 
+ itest7a    | b           | YES         | NO          | 
+ itest7b    | a           | YES         | NO          | 
+ itest7c    | a           | NO          | YES         | ALWAYS
+ itest7d    | a           | NO          | YES         | ALWAYS
+ itest7e    | a           | NO          | NO          | 
+(7 rows)
+
+-- These ALTER TABLE variants will not recurse.
+ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT;
+ALTER TABLE itest7 ALTER COLUMN a RESTART;
+ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY;
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+ a | b 
+---+---
+ 1 | 
+(1 row)
+
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/expected/sequence.out b/src/test/regress/expected/sequence.out
index f339489151..469c082ad1 100644
--- a/src/test/regress/expected/sequence.out
+++ b/src/test/regress/expected/sequence.out
@@ -20,8 +20,8 @@ ERROR:  CACHE (0) must be greater than zero
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
 ERROR:  invalid OWNED BY option
 HINT:  Specify OWNED BY table.column or OWNED BY NONE.
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
-ERROR:  referenced relation "pg_tables" is not a table or foreign table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
+ERROR:  referenced relation "pg_class_oid_index" is not a table or foreign table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 ERROR:  sequence must be in same schema as table it is linked to
 CREATE TABLE sequence_test_table (a int);
diff --git a/src/test/regress/expected/truncate.out b/src/test/regress/expected/truncate.out
index 81612d8c88..b652562f5b 100644
--- a/src/test/regress/expected/truncate.out
+++ b/src/test/regress/expected/truncate.out
@@ -393,6 +393,36 @@ SELECT * FROM truncate_a;
   2 |  34
 (2 rows)
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
+TRUNCATE truncate_b;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 46
+ 47
+(2 rows)
+
+TRUNCATE truncate_b RESTART IDENTITY;
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+ id 
+----
+ 44
+ 45
+(2 rows)
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 9f95b016fd..1f8f0987e3 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -111,6 +111,11 @@ test: select_views portals_p2 foreign_key cluster dependency guc bitmapops combo
 # ----------
 test: plancache limit plpgsql copy2 temp domain rangefuncs prepare without_oid conversion truncate alter_table sequence polymorphism rowtypes returning largeobject with xml
 
+# ----------
+# Another group of parallel tests
+# ----------
+test: identity
+
 # event triggers cannot run concurrently with any test that runs DDL
 test: event_trigger
 
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index e026b7cc90..04206c3162 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -170,6 +170,7 @@ test: conversion
 test: truncate
 test: alter_table
 test: sequence
+test: identity
 test: polymorphism
 test: rowtypes
 test: returning
diff --git a/src/test/regress/sql/create_table_like.sql b/src/test/regress/sql/create_table_like.sql
index 900ca804cb..557040bbe7 100644
--- a/src/test/regress/sql/create_table_like.sql
+++ b/src/test/regress/sql/create_table_like.sql
@@ -37,6 +37,20 @@ CREATE TABLE inhg (x text, LIKE inhx INCLUDING CONSTRAINTS, y text); /* Copies c
 SELECT * FROM inhg; /* Two records with three columns in order x=x, xx=text, y=y */
 DROP TABLE inhg;
 
+CREATE TABLE test_like_id_1 (a int GENERATED ALWAYS AS IDENTITY, b text);
+\d test_like_id_1
+INSERT INTO test_like_id_1 (b) VALUES ('b1');
+SELECT * FROM test_like_id_1;
+CREATE TABLE test_like_id_2 (LIKE test_like_id_1);
+\d test_like_id_2
+INSERT INTO test_like_id_2 (b) VALUES ('b2');
+SELECT * FROM test_like_id_2;  -- identity was not copied
+CREATE TABLE test_like_id_3 (LIKE test_like_id_1 INCLUDING IDENTITY);
+\d test_like_id_3
+INSERT INTO test_like_id_3 (b) VALUES ('b3');
+SELECT * FROM test_like_id_3;  -- identity was copied and applied
+DROP TABLE test_like_id_1, test_like_id_2, test_like_id_3;
+
 CREATE TABLE inhg (x text, LIKE inhx INCLUDING INDEXES, y text); /* copies indexes */
 INSERT INTO inhg VALUES (5, 10);
 INSERT INTO inhg VALUES (20, 10); -- should fail
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
new file mode 100644
index 0000000000..a7e7b15737
--- /dev/null
+++ b/src/test/regress/sql/identity.sql
@@ -0,0 +1,192 @@
+-- sanity check of system catalog
+SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN ('', 'a', 'd');
+
+
+CREATE TABLE itest1 (a int generated by default as identity, b text);
+CREATE TABLE itest2 (a bigint generated always as identity, b text);
+CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
+ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
+
+-- internal sequences should not be shown here
+SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
+
+CREATE TABLE itest4 (a int, b text);
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
+ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
+ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+
+-- for later
+ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
+
+-- invalid column type
+CREATE TABLE itest_err_1 (a text generated by default as identity);
+
+-- duplicate identity
+CREATE TABLE itest_err_2 (a int generated always as identity generated by default as identity);
+
+-- cannot have default and identity
+CREATE TABLE itest_err_3 (a int default 5 generated by default as identity);
+
+-- cannot combine serial and identity
+CREATE TABLE itest_err_4 (a serial generated by default as identity);
+
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest1 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest2 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest3 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+INSERT INTO itest4 DEFAULT VALUES;
+
+SELECT * FROM itest1;
+SELECT * FROM itest2;
+SELECT * FROM itest3;
+SELECT * FROM itest4;
+
+
+-- OVERRIDING tests
+
+INSERT INTO itest1 VALUES (10, 'xyz');
+INSERT INTO itest1 OVERRIDING USER VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest1;
+
+INSERT INTO itest2 VALUES (10, 'xyz');
+INSERT INTO itest2 OVERRIDING SYSTEM VALUE VALUES (10, 'xyz');
+
+SELECT * FROM itest2;
+
+
+-- UPDATE tests
+
+UPDATE itest1 SET a = 101 WHERE a = 1;
+UPDATE itest1 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest1;
+
+UPDATE itest2 SET a = 101 WHERE a = 1;
+UPDATE itest2 SET a = DEFAULT WHERE a = 2;
+SELECT * FROM itest2;
+
+
+-- DROP IDENTITY tests
+
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY;  -- error
+ALTER TABLE itest4 ALTER COLUMN a DROP IDENTITY IF EXISTS;  -- noop
+
+INSERT INTO itest4 DEFAULT VALUES;  -- fails because NOT NULL is not dropped
+ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;
+INSERT INTO itest4 DEFAULT VALUES;
+SELECT * FROM itest4;
+
+-- check that sequence is removed
+SELECT sequence_name FROM itest4_a_seq;
+
+
+-- test views
+
+CREATE TABLE itest10 (a int generated by default as identity, b text);
+CREATE TABLE itest11 (a int generated always as identity, b text);
+
+CREATE VIEW itestv10 AS SELECT * FROM itest10;
+CREATE VIEW itestv11 AS SELECT * FROM itest11;
+
+INSERT INTO itestv10 DEFAULT VALUES;
+INSERT INTO itestv10 DEFAULT VALUES;
+
+INSERT INTO itestv11 DEFAULT VALUES;
+INSERT INTO itestv11 DEFAULT VALUES;
+
+SELECT * FROM itestv10;
+SELECT * FROM itestv11;
+
+INSERT INTO itestv10 VALUES (10, 'xyz');
+INSERT INTO itestv10 OVERRIDING USER VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv10;
+
+INSERT INTO itestv11 VALUES (10, 'xyz');
+INSERT INTO itestv11 OVERRIDING SYSTEM VALUE VALUES (11, 'xyz');
+
+SELECT * FROM itestv11;
+
+
+-- various ALTER COLUMN tests
+
+-- fail, not allowed for identity columns
+ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
+
+-- fail, not allowed, already has a default
+CREATE TABLE itest5 (a serial, b text);
+ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE int;
+SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
+\d itest3
+
+ALTER TABLE itest3 ALTER COLUMN a TYPE text;  -- error
+
+
+-- ALTER COLUMN ... SET
+
+CREATE TABLE itest6 (a int GENERATED ALWAYS AS IDENTITY, b text);
+INSERT INTO itest6 DEFAULT VALUES;
+
+ALTER TABLE itest6 ALTER COLUMN a SET GENERATED BY DEFAULT SET INCREMENT BY 2 SET START WITH 100 RESTART;
+INSERT INTO itest6 DEFAULT VALUES;
+INSERT INTO itest6 DEFAULT VALUES;
+SELECT * FROM itest6;
+
+SELECT table_name, column_name, is_identity, identity_generation FROM information_schema.columns WHERE table_name = 'itest6';
+
+ALTER TABLE itest6 ALTER COLUMN b SET INCREMENT BY 2;  -- fail, not identity
+
+
+-- prohibited direct modification of sequence
+
+ALTER SEQUENCE itest6_a_seq OWNED BY NONE;
+
+
+-- inheritance
+
+CREATE TABLE itest7 (a int GENERATED ALWAYS AS IDENTITY);
+INSERT INTO itest7 DEFAULT VALUES;
+SELECT * FROM itest7;
+
+-- identity property is not inherited
+CREATE TABLE itest7a (b text) INHERITS (itest7);
+
+-- make column identity in child table
+CREATE TABLE itest7b (a int);
+CREATE TABLE itest7c (a int GENERATED ALWAYS AS IDENTITY) INHERITS (itest7b);
+INSERT INTO itest7c DEFAULT VALUES;
+SELECT * FROM itest7c;
+
+CREATE TABLE itest7d (a int not null);
+CREATE TABLE itest7e () INHERITS (itest7d);
+ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
+
+SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
+
+-- These ALTER TABLE variants will not recurse.
+ALTER TABLE itest7 ALTER COLUMN a SET GENERATED BY DEFAULT;
+ALTER TABLE itest7 ALTER COLUMN a RESTART;
+ALTER TABLE itest7 ALTER COLUMN a DROP IDENTITY;
+
+-- privileges
+CREATE USER regress_user1;
+CREATE TABLE itest8 (a int GENERATED ALWAYS AS IDENTITY, b text);
+GRANT SELECT, INSERT ON itest8 TO regress_user1;
+SET ROLE regress_user1;
+INSERT INTO itest8 DEFAULT VALUES;
+SELECT * FROM itest8;
+RESET ROLE;
+DROP TABLE itest8;
+DROP USER regress_user1;
diff --git a/src/test/regress/sql/sequence.sql b/src/test/regress/sql/sequence.sql
index 0fbd255967..18fa6ae5e9 100644
--- a/src/test/regress/sql/sequence.sql
+++ b/src/test/regress/sql/sequence.sql
@@ -13,7 +13,7 @@ CREATE SEQUENCE sequence_testx CACHE 0;
 
 -- OWNED BY errors
 CREATE SEQUENCE sequence_testx OWNED BY nobody;  -- nonsense word
-CREATE SEQUENCE sequence_testx OWNED BY pg_tables.tablename;  -- not a table
+CREATE SEQUENCE sequence_testx OWNED BY pg_class_oid_index.oid;  -- not a table
 CREATE SEQUENCE sequence_testx OWNED BY pg_class.relname;  -- not same schema
 CREATE TABLE sequence_test_table (a int);
 CREATE SEQUENCE sequence_testx OWNED BY sequence_test_table.b;  -- wrong column
diff --git a/src/test/regress/sql/truncate.sql b/src/test/regress/sql/truncate.sql
index d61eea1a42..9d3d8de54a 100644
--- a/src/test/regress/sql/truncate.sql
+++ b/src/test/regress/sql/truncate.sql
@@ -202,6 +202,24 @@ CREATE TABLE truncate_a (id serial,
 INSERT INTO truncate_a DEFAULT VALUES;
 SELECT * FROM truncate_a;
 
+CREATE TABLE truncate_b (id int GENERATED ALWAYS AS IDENTITY (START WITH 44));
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
+TRUNCATE truncate_b RESTART IDENTITY;
+
+INSERT INTO truncate_b DEFAULT VALUES;
+INSERT INTO truncate_b DEFAULT VALUES;
+SELECT * FROM truncate_b;
+
 -- check rollback of a RESTART IDENTITY operation
 BEGIN;
 TRUNCATE truncate_a RESTART IDENTITY;
-- 
2.12.2

From f06d99b1d217d5564b70dff5e6f34267c48ecbc6 Mon Sep 17 00:00:00 2001
From: Vitaly Burovoy <vitaly.burovoy@gmail.com>
Date: Fri, 7 Apr 2017 05:00:54 +0000
Subject: [PATCH] Implement SET IDENTITY ... IF NOT EXISTS

Delete ADD GENERATED syntax since it does not confirm with the standard
and there is no way to add "identity property" twice to a single column.

The SET IDENTITY ... IF NOT EXISTS seems better and works similar way
as SET DEFAULT does.
---
 doc/src/sgml/ref/alter_table.sgml      |  20 ++++--
 src/backend/commands/tablecmds.c       | 118 ++++++++-------------------------
 src/backend/parser/gram.y              |  41 ++++++------
 src/backend/parser/parse_utilcmd.c     | 102 +++++++++++++++++-----------
 src/bin/pg_dump/pg_dump.c              |  39 ++++++-----
 src/include/nodes/parsenodes.h         |   1 -
 src/test/regress/expected/identity.out |  17 +++--
 src/test/regress/sql/identity.sql      |  14 ++--
 8 files changed, 163 insertions(+), 189 deletions(-)

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 56ea830..847573c 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -46,8 +46,8 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET DEFAULT <replaceable class="PARAMETER">expression</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP DEFAULT
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET | DROP } NOT NULL
-    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( <replaceable>sequence_options</replaceable> ) ]
-    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> { SET GENERATED { ALWAYS | BY DEFAULT } | SET <replaceable>sequence_option</replaceable> | RESTART [ [ WITH ] <replaceable class="parameter">restart</replaceable> ] } [...]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET GENERATED { ALWAYS | BY DEFAULT } [ IF NOT EXISTS ] [ identity_sequence_option [ ... ] ]
+    ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> identity_sequence_option [ ... ]
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> DROP IDENTITY [ IF EXISTS ]
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET STATISTICS <replaceable class="PARAMETER">integer</replaceable>
     ALTER [ COLUMN ] <replaceable class="PARAMETER">column_name</replaceable> SET ( <replaceable class="PARAMETER">attribute_option</replaceable> = <replaceable class="PARAMETER">value</replaceable> [, ... ] )
@@ -85,6 +85,9 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
     OWNER TO { <replaceable class="PARAMETER">new_owner</replaceable> | CURRENT_USER | SESSION_USER }
     REPLICA IDENTITY { DEFAULT | USING INDEX <replaceable class="PARAMETER">index_name</replaceable> | FULL | NOTHING }
 
+<phrase>and <replaceable class="PARAMETER">identity_sequence_option</replaceable> is:</phrase>
+    { SET sequence_option | RESTART [ [ WITH ] restart }
+
 <phrase>and <replaceable class="PARAMETER">table_constraint_using_index</replaceable> is:</phrase>
 
     [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
@@ -191,7 +194,6 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
    </varlistentry>
 
    <varlistentry>
-    <term><literal>ADD GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY</literal></term>
     <term><literal>SET GENERATED { ALWAYS | BY DEFAULT }</literal></term>
     <term><literal>DROP IDENTITY [ IF EXISTS ]</literal></term>
     <listitem>
@@ -202,6 +204,12 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
      </para>
 
      <para>
+      If <literal>SET GENERATED ... IF NOT EXISTS</literal> is specified and the
+      column is not an identity column, no error is thrown.  In this case the
+      column is set as an <firstterm>identity column</firstterm>.
+     </para>
+
+     <para>
       If <literal>DROP IDENTITY IF EXISTS</literal> is specified and the
       column is not an identity column, no error is thrown.  In this case a
       notice is issued instead.
@@ -1195,8 +1203,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
    </para>
 
    <para>
-    The actions for identity columns (<literal>ADD
-    GENERATED</literal>, <literal>SET</literal> etc., <literal>DROP
+    The actions for identity columns (<literal>SET</literal> etc., <literal>DROP
     IDENTITY</literal>), as well as the actions
     <literal>TRIGGER</>, <literal>CLUSTER</>, <literal>OWNER</>,
     and <literal>TABLESPACE</> never recurse to descendant tables;
@@ -1411,7 +1418,8 @@ ALTER TABLE cities
    The forms <literal>ADD</literal> (without <literal>USING INDEX</literal>),
    <literal>DROP [COLUMN]</>, <literal>DROP IDENTITY</literal>, <literal>RESTART</literal>,
    <literal>SET DEFAULT</>, <literal>SET DATA TYPE</literal> (without <literal>USING</literal>),
-   <literal>SET GENERATED</literal>, and <literal>SET <replaceable>sequence_option</replaceable></literal>
+   <literal>SET GENERATED</literal> (without <literal>IF NOT EXISTS</literal>),
+   and <literal>SET <replaceable>sequence_option</replaceable></literal>
    conform with the SQL standard.  The other forms are
    <productname>PostgreSQL</productname> extensions of the SQL standard.
    Also, the ability to specify more than one manipulation in a single
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 60f8b7f..e930a58 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -361,10 +361,8 @@ static ObjectAddress ATExecSetNotNull(AlteredTableInfo *tab, Relation rel,
 				 const char *colName, LOCKMODE lockmode);
 static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 					Node *newDefault, LOCKMODE lockmode);
-static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
-					Node *def, LOCKMODE lockmode);
 static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
-					Node *def, LOCKMODE lockmode);
+					bool missing_ok, Node *def, LOCKMODE lockmode);
 static ObjectAddress ATExecDropIdentity(Relation rel, const char *colName, bool missing_ok, LOCKMODE lockmode);
 static void ATPrepSetStatistics(Relation rel, const char *colName,
 					Node *newValue, LOCKMODE lockmode);
@@ -3231,7 +3229,6 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_DisableRowSecurity:
 			case AT_ForceRowSecurity:
 			case AT_NoForceRowSecurity:
-			case AT_AddIdentity:
 			case AT_DropIdentity:
 			case AT_SetIdentity:
 				cmd_lockmode = AccessExclusiveLock;
@@ -3464,10 +3461,6 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* No command-specific prep needed */
 			pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
 			break;
-		case AT_AddIdentity:
-			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
-			pass = AT_PASS_ADD_CONSTR;
-			break;
 		case AT_DropIdentity:
 			ATSimplePermissions(rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
 			pass = AT_PASS_DROP;
@@ -3801,11 +3794,9 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		case AT_ColumnDefault:	/* ALTER COLUMN DEFAULT */
 			address = ATExecColumnDefault(rel, cmd->name, cmd->def, lockmode);
 			break;
-		case AT_AddIdentity:
-			address = ATExecAddIdentity(rel, cmd->name, cmd->def, lockmode);
-			break;
 		case AT_SetIdentity:
-			address = ATExecSetIdentity(rel, cmd->name, cmd->def, lockmode);
+			address = ATExecSetIdentity(rel, cmd->name, cmd->missing_ok,
+										cmd->def, lockmode);
 			break;
 		case AT_DropIdentity:
 			address = ATExecDropIdentity(rel, cmd->name, cmd->missing_ok, lockmode);
@@ -5853,84 +5844,13 @@ ATExecColumnDefault(Relation rel, const char *colName,
 }
 
 /*
- * ALTER TABLE ALTER COLUMN ADD IDENTITY
- *
- * Return the address of the affected column.
- */
-static ObjectAddress
-ATExecAddIdentity(Relation rel, const char *colName,
-				  Node *def, LOCKMODE lockmode)
-{
-	Relation	attrelation;
-	HeapTuple	tuple;
-	Form_pg_attribute attTup;
-	AttrNumber	attnum;
-	ObjectAddress address;
-	ColumnDef  *cdef = castNode(ColumnDef, def);
-
-	attrelation = heap_open(AttributeRelationId, RowExclusiveLock);
-
-	tuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), colName);
-	if (!HeapTupleIsValid(tuple))
-		ereport(ERROR,
-				(errcode(ERRCODE_UNDEFINED_COLUMN),
-				 errmsg("column \"%s\" of relation \"%s\" does not exist",
-						colName, RelationGetRelationName(rel))));
-	attTup = (Form_pg_attribute) GETSTRUCT(tuple);
-	attnum = attTup->attnum;
-
-	/* Can't alter a system attribute */
-	if (attnum <= 0)
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("cannot alter system column \"%s\"",
-						colName)));
-
-	/*
-	 * Creating a column as identity implies NOT NULL, so adding the identity
-	 * to an existing column that is not NOT NULL would create a state that
-	 * cannot be reproduced without contortions.
-	 */
-	if (!attTup->attnotnull)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
-						colName, RelationGetRelationName(rel))));
-
-	if (attTup->attidentity)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("column \"%s\" of relation \"%s\" is already an identity column",
-						colName, RelationGetRelationName(rel))));
-
-	if (attTup->atthasdef)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("column \"%s\" of relation \"%s\" already has a default value",
-						colName, RelationGetRelationName(rel))));
-
-	attTup->attidentity = cdef->identity;
-	CatalogTupleUpdate(attrelation, &tuple->t_self, tuple);
-
-	InvokeObjectPostAlterHook(RelationRelationId,
-							  RelationGetRelid(rel),
-							  attTup->attnum);
-	ObjectAddressSubSet(address, RelationRelationId,
-						RelationGetRelid(rel), attnum);
-	heap_freetuple(tuple);
-
-	heap_close(attrelation, RowExclusiveLock);
-
-	return address;
-}
-
-/*
  * ALTER TABLE ALTER COLUMN SET { GENERATED or sequence options }
  *
  * Return the address of the affected column.
  */
 static ObjectAddress
-ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmode)
+ATExecSetIdentity(Relation rel, const char *colName, bool missing_ok,
+				  Node *def, LOCKMODE lockmode)
 {
 	ListCell   *option;
 	DefElem	   *generatedEl = NULL;
@@ -5981,10 +5901,30 @@ ATExecSetIdentity(Relation rel, const char *colName, Node *def, LOCKMODE lockmod
 						colName)));
 
 	if (!attTup->attidentity)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
-						colName, RelationGetRelationName(rel))));
+	{
+		if(!missing_ok)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("column \"%s\" of relation \"%s\" is not an identity column",
+							colName, RelationGetRelationName(rel))));
+
+		/*
+		 * Creating a column as identity implies NOT NULL, so adding the identity
+		 * to an existing column that is not NOT NULL would create a state that
+		 * cannot be reproduced without contortions.
+		 */
+		if (!attTup->attnotnull)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("column \"%s\" of relation \"%s\" must be declared NOT NULL before identity can be added",
+							colName, RelationGetRelationName(rel))));
+
+		if (attTup->atthasdef)
+			ereport(ERROR,
+					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+					 errmsg("column \"%s\" of relation \"%s\" already has a default value",
+							colName, RelationGetRelationName(rel))));
+	}
 
 	if (generatedEl)
 	{
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 29ca5f1..8010952 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -292,7 +292,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <node>	alter_table_cmd alter_type_cmd opt_collate_clause
 	   replica_identity partition_cmd
 %type <list>	alter_table_cmds alter_type_cmds
-%type <list>    alter_identity_column_option_list
+%type <list>    alter_identity_column_options alter_identity_column_option_list
 %type <defelt>  alter_identity_column_option
 
 %type <dbehavior>	opt_drop_behavior
@@ -2132,32 +2132,28 @@ alter_table_cmd:
 					n->def = (Node *) makeString($6);
 					$$ = (Node *)n;
 				}
-			/* ALTER TABLE <name> ALTER [COLUMN] <colname> ADD GENERATED ... AS IDENTITY ... */
-			| ALTER opt_column ColId ADD_P GENERATED generated_when AS IDENTITY_P OptParenthesizedSeqOptList
-				{
-					AlterTableCmd *n = makeNode(AlterTableCmd);
-					Constraint *c = makeNode(Constraint);
-
-					c->contype = CONSTR_IDENTITY;
-					c->generated_when = $6;
-					c->options = $9;
-					c->location = @5;
-
-					n->subtype = AT_AddIdentity;
-					n->name = $3;
-					n->def = (Node *) c;
-
-					$$ = (Node *)n;
-				}
 			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET <sequence options>/RESET */
 			| ALTER opt_column ColId alter_identity_column_option_list
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
 					n->subtype = AT_SetIdentity;
 					n->name = $3;
+					n->missing_ok = false;
 					n->def = (Node *) $4;
 					$$ = (Node *)n;
 				}
+			/* ALTER TABLE <name> ALTER [COLUMN] <colname> SET GENERATED <when> [IF NOT EXISTS] SET <sequence options>/RESET */
+			| ALTER opt_column ColId SET GENERATED generated_when opt_if_not_exists alter_identity_column_options
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					List *generated = (List *)makeDefElem("generated", (Node *) makeInteger($6), @6);
+
+					n->subtype = AT_SetIdentity;
+					n->name = $3;
+					n->missing_ok = $7;
+					n->def = (Node *) lappend($8, generated);
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> ALTER [COLUMN] <colname> DROP IDENTITY */
 			| ALTER opt_column ColId DROP IDENTITY_P
 				{
@@ -2613,6 +2609,11 @@ reloption_elem:
 				}
 		;
 
+alter_identity_column_options:
+			alter_identity_column_option_list		{ $$ = $1; }
+			| /* EMPTY */							{ $$ = NIL; }
+			;
+
 alter_identity_column_option_list:
 			alter_identity_column_option
 				{ $$ = list_make1($1); }
@@ -2640,10 +2641,6 @@ alter_identity_column_option:
 								 parser_errposition(@2)));
 					$$ = $2;
 				}
-			| SET GENERATED generated_when
-				{
-					$$ = makeDefElem("generated", (Node *) makeInteger($3), @1);
-				}
 		;
 
 ForValues:
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 9266996..315e56f 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -2783,43 +2783,22 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 					break;
 				}
 
-			case AT_AddIdentity:
-				{
-					Constraint  *def = castNode(Constraint, cmd->def);
-					ColumnDef *newdef = makeNode(ColumnDef);
-					AttrNumber	attnum;
-
-					newdef->colname = cmd->name;
-					newdef->identity = def->generated_when;
-					cmd->def = (Node *) newdef;
-
-					attnum = get_attnum(relid, cmd->name);
-					/* if attribute not found, something will error about it later */
-					if (attnum != InvalidAttrNumber)
-						generateSerialExtraStmts(&cxt, newdef,
-												 get_atttype(relid, attnum),
-												 def->options, true,
-												 NULL, NULL);
-
-					newcmds = lappend(newcmds, cmd);
-					break;
-				}
-
 			case AT_SetIdentity:
 				{
 					/*
-					 * Create an ALTER SEQUENCE statement for the internal
-					 * sequence of the identity column.
+					 * Create an CREATE/ALTER SEQUENCE statement for the
+					 * internal sequence of the identity column.
 					 */
 					ListCell   *lc;
 					List	   *newseqopts = NIL;
 					List	   *newdef = NIL;
+					List	   *seqname = NIL;
 					List	   *seqlist;
 					AttrNumber	attnum;
 
 					/*
-					 * Split options into those handled by ALTER SEQUENCE and
-					 * those for ALTER TABLE proper.
+					 * Split options into those handled by CREATE/ALTER SEQUENCE
+					 * and those for ALTER TABLE proper.
 					 */
 					foreach(lc, castNode(List, cmd->def))
 					{
@@ -2827,6 +2806,8 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 
 						if (strcmp(def->defname, "generated") == 0)
 							newdef = lappend(newdef, def);
+						else if (strcmp(def->defname, "sequence_name") == 0)
+							seqname = lappend(seqname, def);
 						else
 							newseqopts = lappend(newseqopts, def);
 					}
@@ -2835,25 +2816,66 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 
 					if (attnum)
 					{
-						seqlist = getOwnedSequences(relid, attnum);
-						if (seqlist)
+						/*
+						 * cmd->missing_ok can be set to true iff "generated"
+						 * is present
+						 */
+						if (!get_attidentity(relid, attnum) && cmd->missing_ok)
 						{
-							AlterSeqStmt *seqstmt;
-							Oid			seq_relid;
+							/* CREATE SEQUENCE */
+							ColumnDef *newcoldef = makeNode(ColumnDef);
+							newcoldef->colname = cmd->name;
 
-							seqstmt = makeNode(AlterSeqStmt);
-							seq_relid = linitial_oid(seqlist);
-							seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
-															 get_rel_name(seq_relid), -1);
-							seqstmt->options = newseqopts;
-							seqstmt->for_identity = true;
-							seqstmt->missing_ok = false;
+							newseqopts = list_concat(newseqopts, seqname);
+							generateSerialExtraStmts(&cxt, newcoldef,
+													 get_atttype(relid, attnum),
+													 newseqopts, true,
+													 NULL, NULL);
+						}
+						else
+						{
+							/* ALTER SEQUENCE */
+							seqlist = getOwnedSequences(relid, attnum);
+							if (seqlist)
+							{
+								AlterSeqStmt *seqstmt;
+								Oid			seq_relid;
 
-							cxt.alist = lappend(cxt.alist, seqstmt);
+								seqstmt = makeNode(AlterSeqStmt);
+								seq_relid = linitial_oid(seqlist);
+								seqstmt->sequence = makeRangeVar(get_namespace_name(get_rel_namespace(seq_relid)),
+																 get_rel_name(seq_relid), -1);
+								seqstmt->options = newseqopts;
+								seqstmt->for_identity = true;
+								seqstmt->missing_ok = false;
+
+								cxt.alist = lappend(cxt.alist, seqstmt);
+
+								if (seqname)
+								{
+									/*
+									 * ALTER SEQUENCE ... RENAME TO ...
+									 * if the old name differs from the new one.
+									 */
+									char *new_seqname = NameListToString(defGetQualifiedName(linitial(seqname)));
+									if (strcmp(new_seqname, seqstmt->sequence->relname) != 0)
+									{
+										RenameStmt *n = makeNode(RenameStmt);
+										n->renameType = OBJECT_SEQUENCE;
+										n->relation = seqstmt->sequence;
+										n->subname = NULL;
+										n->newname = new_seqname;
+										n->missing_ok = false;
+
+										cxt.alist = lappend(cxt.alist, n);
+									}
+								}
+							}
 						}
 					}
-					/* If column was not found or was not an identity column, we
-					 * just let the ALTER TABLE command error out later. */
+					/* If column was not found or was not an identity column and
+					 * IF NOT EXISTS is not present, we just let the ALTER TABLE
+					 * command error out later. */
 
 					cmd->def = (Node *) newdef;
 					newcmds = lappend(newcmds, cmd);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 65a2f23..d9cf2f6 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -16246,6 +16246,7 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 			   *seqtype;
 	bool		cycled;
 	bool		is_ascending;
+	char	   *opts_prefix = "";
 	PQExpBuffer query = createPQExpBuffer();
 	PQExpBuffer delqry = createPQExpBuffer();
 	PQExpBuffer labelq = createPQExpBuffer();
@@ -16376,14 +16377,15 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 						  "ALTER TABLE %s ",
 						  fmtId(owning_tab->dobj.name));
 		appendPQExpBuffer(query,
-						  "ALTER COLUMN %s ADD GENERATED ",
+						  "ALTER COLUMN %s SET GENERATED ",
 						  fmtId(owning_tab->attnames[tbinfo->owning_col - 1]));
 		if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_ALWAYS)
 			appendPQExpBuffer(query, "ALWAYS");
 		else if (owning_tab->attidentity[tbinfo->owning_col - 1] == ATTRIBUTE_IDENTITY_BY_DEFAULT)
 			appendPQExpBuffer(query, "BY DEFAULT");
-		appendPQExpBuffer(query, " AS IDENTITY (\n    SEQUENCE NAME %s\n",
+		appendPQExpBuffer(query, " IF NOT EXISTS\n    SET SEQUENCE NAME %s\n",
 						  fmtId(tbinfo->dobj.name));
+		opts_prefix = "SET ";
 	}
 	else
 	{
@@ -16396,28 +16398,35 @@ dumpSequence(Archive *fout, TableInfo *tbinfo)
 	}
 
 	if (fout->remoteVersion >= 80400)
-		appendPQExpBuffer(query, "    START WITH %s\n", startv);
+		appendPQExpBuffer(query, "    %sSTART WITH %s\n", opts_prefix, startv);
 
-	appendPQExpBuffer(query, "    INCREMENT BY %s\n", incby);
+	appendPQExpBuffer(query, "    %sINCREMENT BY %s\n", opts_prefix, incby);
 
 	if (minv)
-		appendPQExpBuffer(query, "    MINVALUE %s\n", minv);
+		appendPQExpBuffer(query, "    %sMINVALUE %s\n", opts_prefix, minv);
 	else
-		appendPQExpBufferStr(query, "    NO MINVALUE\n");
+		appendPQExpBuffer(query, "    %sNO MINVALUE\n", opts_prefix);
 
 	if (maxv)
-		appendPQExpBuffer(query, "    MAXVALUE %s\n", maxv);
+		appendPQExpBuffer(query, "    %sMAXVALUE %s\n", opts_prefix, maxv);
 	else
-		appendPQExpBufferStr(query, "    NO MAXVALUE\n");
+		appendPQExpBuffer(query, "    %sNO MAXVALUE\n", opts_prefix);
 
-	appendPQExpBuffer(query,
-					  "    CACHE %s%s",
-					  cache, (cycled ? "\n    CYCLE" : ""));
-
-	if (tbinfo->is_identity_sequence)
-		appendPQExpBufferStr(query, "\n);\n");
+	if (!tbinfo->is_identity_sequence)
+		appendPQExpBuffer(query,
+						  "    CACHE %s%s",
+						  cache, (cycled ? "\n    CYCLE" : ""));
 	else
-		appendPQExpBufferStr(query, ";\n");
+	{
+		appendPQExpBuffer(query, "    %sCACHE %s\n", opts_prefix, cache);
+
+		if (cycled)
+			appendPQExpBuffer(query, "    %sCYCLE", opts_prefix);
+		else
+			appendPQExpBuffer(query, "    %sNO CYCLE", opts_prefix);
+	}
+
+	appendPQExpBufferStr(query, ";\n");
 
 	appendPQExpBuffer(labelq, "SEQUENCE %s", fmtId(tbinfo->dobj.name));
 
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 9f57388..a40963a 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1726,7 +1726,6 @@ typedef enum AlterTableType
 	AT_GenericOptions,			/* OPTIONS (...) */
 	AT_AttachPartition,			/* ATTACH PARTITION */
 	AT_DetachPartition,			/* DETACH PARTITION */
-	AT_AddIdentity,				/* ADD IDENTITY */
 	AT_SetIdentity,				/* SET identity column options */
 	AT_DropIdentity				/* DROP IDENTITY */
 } AlterTableType;
diff --git a/src/test/regress/expected/identity.out b/src/test/regress/expected/identity.out
index 88b56da..a6b0e92 100644
--- a/src/test/regress/expected/identity.out
+++ b/src/test/regress/expected/identity.out
@@ -7,8 +7,6 @@ SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN
 CREATE TABLE itest1 (a int generated by default as identity, b text);
 CREATE TABLE itest2 (a bigint generated always as identity, b text);
 CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
-ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
-ERROR:  column "a" of relation "itest3" is already an identity column
 SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
  table_name | column_name | column_default | is_nullable | is_identity | identity_generation | identity_start | identity_increment |  identity_maximum   | identity_minimum | identity_cycle 
 ------------+-------------+----------------+-------------+-------------+---------------------+----------------+--------------------+---------------------+------------------+----------------
@@ -27,15 +25,16 @@ SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE
 (0 rows)
 
 CREATE TABLE itest4 (a int, b text);
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;  -- error, requires NOT NULL
 ERROR:  column "a" of relation "itest4" must be declared NOT NULL before identity can be added
 ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED BY DEFAULT;  -- error, must be identity without "IF NOT EXISTS"
+ERROR:  column "a" of relation "itest4" is not an identity column
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED BY DEFAULT IF NOT EXISTS;  -- ok
 ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
 ERROR:  column "a" of relation "itest4" is an identity column
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
-ERROR:  column "a" of relation "itest4" is already an identity column
-ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;  -- ok, just update
+ALTER TABLE itest4 ALTER COLUMN b SET GENERATED ALWAYS IF NOT EXISTS;  -- error, wrong data type
 ERROR:  identity column type must be smallint, integer, or bigint
 -- for later
 ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
@@ -217,7 +216,7 @@ ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
 ERROR:  column "a" of relation "itest1" is an identity column
 -- fail, not allowed, already has a default
 CREATE TABLE itest5 (a serial, b text);
-ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest5 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;
 ERROR:  column "a" of relation "itest5" already has a default value
 ALTER TABLE itest3 ALTER COLUMN a TYPE int;
 SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
@@ -286,7 +285,7 @@ SELECT * FROM itest7c;
 
 CREATE TABLE itest7d (a int not null);
 CREATE TABLE itest7e () INHERITS (itest7d);
-ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;
 ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
 ERROR:  cannot recursively add identity column to table that has child tables
 SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
diff --git a/src/test/regress/sql/identity.sql b/src/test/regress/sql/identity.sql
index a7e7b15..4db78c5 100644
--- a/src/test/regress/sql/identity.sql
+++ b/src/test/regress/sql/identity.sql
@@ -5,7 +5,6 @@ SELECT attrelid, attname, attidentity FROM pg_attribute WHERE attidentity NOT IN
 CREATE TABLE itest1 (a int generated by default as identity, b text);
 CREATE TABLE itest2 (a bigint generated always as identity, b text);
 CREATE TABLE itest3 (a smallint generated by default as identity (start with 7 increment by 5), b text);
-ALTER TABLE itest3 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error
 
 SELECT table_name, column_name, column_default, is_nullable, is_identity, identity_generation, identity_start, identity_increment, identity_maximum, identity_minimum, identity_cycle FROM information_schema.columns WHERE table_name LIKE 'itest_' ORDER BY 1, 2;
 
@@ -13,12 +12,13 @@ SELECT table_name, column_name, column_default, is_nullable, is_identity, identi
 SELECT sequence_name FROM information_schema.sequences WHERE sequence_name LIKE 'itest%';
 
 CREATE TABLE itest4 (a int, b text);
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, requires NOT NULL
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;  -- error, requires NOT NULL
 ALTER TABLE itest4 ALTER COLUMN a SET NOT NULL;
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- ok
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED BY DEFAULT;  -- error, must be identity without "IF NOT EXISTS"
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED BY DEFAULT IF NOT EXISTS;  -- ok
 ALTER TABLE itest4 ALTER COLUMN a DROP NOT NULL;  -- error, disallowed
-ALTER TABLE itest4 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;  -- error, already set
-ALTER TABLE itest4 ALTER COLUMN b ADD GENERATED ALWAYS AS IDENTITY;  -- error, wrong data type
+ALTER TABLE itest4 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;  -- ok, just update
+ALTER TABLE itest4 ALTER COLUMN b SET GENERATED ALWAYS IF NOT EXISTS;  -- error, wrong data type
 
 -- for later
 ALTER TABLE itest4 ALTER COLUMN b SET DEFAULT '';
@@ -124,7 +124,7 @@ ALTER TABLE itest1 ALTER COLUMN a SET DEFAULT 1;
 
 -- fail, not allowed, already has a default
 CREATE TABLE itest5 (a serial, b text);
-ALTER TABLE itest5 ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest5 ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;
 
 ALTER TABLE itest3 ALTER COLUMN a TYPE int;
 SELECT seqtypid::regtype FROM pg_sequence WHERE seqrelid = 'itest3_a_seq'::regclass;
@@ -170,7 +170,7 @@ SELECT * FROM itest7c;
 
 CREATE TABLE itest7d (a int not null);
 CREATE TABLE itest7e () INHERITS (itest7d);
-ALTER TABLE itest7d ALTER COLUMN a ADD GENERATED ALWAYS AS IDENTITY;
+ALTER TABLE itest7d ALTER COLUMN a SET GENERATED ALWAYS IF NOT EXISTS;
 ALTER TABLE itest7d ADD COLUMN b int GENERATED ALWAYS AS IDENTITY;  -- error
 
 SELECT table_name, column_name, is_nullable, is_identity, identity_generation FROM information_schema.columns WHERE table_name LIKE 'itest7%' ORDER BY 1, 2;
-- 
2.7.3