Review of patch renaming constraints

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 951b63b..c3039c8 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -25,6 +25,8 @@ ALTER TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="PARAMETER">name</replacea
     <replaceable class="PARAMETER">action</replaceable> [, ... ]
 ALTER TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
     RENAME [ COLUMN ] <replaceable class="PARAMETER">column</replaceable> TO <replaceable class="PARAMETER">new_column</replaceable>
+ALTER TABLE [ IF EXISTS ] [ ONLY ] <replaceable class="PARAMETER">name</replaceable> [ * ]
+    RENAME CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> TO <replaceable class="PARAMETER">new_constraint_name</replaceable>
 ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
     RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
 ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
@@ -569,8 +571,8 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
     <listitem>
      <para>
       The <literal>RENAME</literal> forms change the name of a table
-      (or an index, sequence, or view) or the name of an individual column in
-      a table. There is no effect on the stored data.
+      (or an index, sequence, or view), the name of an individual column in
+      a table, or the name of a constraint of the table. There is no effect on the stored data.
      </para>
     </listitem>
    </varlistentry>
@@ -883,7 +885,8 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable>
 
    <para>
     If a table has any descendant tables, it is not permitted to add,
-    rename, or change the type of a column in the parent table without doing
+    rename, or change the type of a column, or rename an inherited constraint
+    in the parent table without doing
     the same to the descendants.  That is, <command>ALTER TABLE ONLY</command>
     will be rejected.  This ensures that the descendants always have
     columns matching the parent.
@@ -983,6 +986,13 @@ ALTER TABLE distributors RENAME TO suppliers;
   </para>
 
   <para>
+   To rename an existing constraint:
+<programlisting>
+ALTER TABLE distributors RENAME CONSTRAINT zipchk TO zip_check;
+</programlisting>
+  </para>
+
+  <para>
    To add a not-null constraint to a column:
 <programlisting>
 ALTER TABLE distributors ALTER COLUMN street SET NOT NULL;
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index 9175405..4dd9927 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -57,6 +57,10 @@ ExecRenameStmt(RenameStmt *stmt)
 			RenameCollation(stmt->object, stmt->newname);
 			break;
 
+		case OBJECT_CONSTRAINT:
+			RenameConstraint(stmt);
+			break;
+
 		case OBJECT_CONVERSION:
 			RenameConversion(stmt->object, stmt->newname);
 			break;
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 07dc326..8dcaedc 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -2324,6 +2324,108 @@ renameatt(RenameStmt *stmt)
 					   stmt->behavior);
 }
 
+
+/*
+ * same logic as renameatt_internal
+ */
+static void
+rename_constraint_internal(Oid myrelid,
+						   const char *oldconname,
+						   const char *newconname,
+						   bool recurse,
+						   bool recursing,
+						   int expected_parents)
+{
+	Relation	targetrelation;
+	Oid			constraintOid;
+	HeapTuple   tuple;
+	Form_pg_constraint con;
+
+	targetrelation = relation_open(myrelid, AccessExclusiveLock);
+	/* don't tell it whether we're recursing; we allow changing typed tables here */
+	renameatt_check(myrelid, RelationGetForm(targetrelation), false);
+
+	constraintOid = get_constraint_oid(myrelid, oldconname, false);
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for constraint %u",
+			 constraintOid);
+	con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+	if (con->contype == CONSTRAINT_CHECK && !con->conisonly)
+	{
+		if (recurse)
+		{
+			List	   *child_oids,
+				*child_numparents;
+			ListCell   *lo,
+				*li;
+
+			child_oids = find_all_inheritors(myrelid, AccessExclusiveLock,
+											 &child_numparents);
+
+			forboth(lo, child_oids, li, child_numparents)
+			{
+				Oid			childrelid = lfirst_oid(lo);
+				int			numparents = lfirst_int(li);
+
+				if (childrelid == myrelid)
+					continue;
+
+				rename_constraint_internal(childrelid, oldconname, newconname, false, true, numparents);
+			}
+		}
+		else
+		{
+			if (expected_parents == 0 &&
+				find_inheritance_children(myrelid, NoLock) != NIL)
+				ereport(ERROR,
+						(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+						 errmsg("inherited constraint \"%s\" must be renamed in child tables too",
+								oldconname)));
+		}
+
+		if (con->coninhcount > expected_parents)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
+					 errmsg("cannot rename inherited constraint \"%s\"",
+							oldconname)));
+	}
+
+	if (con->conindid
+		&& (con->contype == CONSTRAINT_PRIMARY
+			|| con->contype == CONSTRAINT_UNIQUE
+			|| con->contype == CONSTRAINT_EXCLUSION))
+		/* rename the index; this renames the constraint as well */
+		RenameRelationInternal(con->conindid, newconname);
+	else
+		RenameConstraintById(constraintOid, newconname);
+
+	ReleaseSysCache(tuple);
+
+	relation_close(targetrelation, NoLock);		/* close rel but keep lock */
+}
+
+void
+RenameConstraint(RenameStmt *stmt)
+{
+	Oid			relid;
+
+	/* lock level taken here should match rename_constraint_internal */
+	relid = RangeVarGetRelidExtended(stmt->relation, AccessExclusiveLock,
+									 false, false,
+									 RangeVarCallbackForRenameAttribute,
+									 NULL);
+
+	rename_constraint_internal(relid,
+							   stmt->subname,
+							   stmt->newname,
+							   interpretInhOption(stmt->relation->inhOpt),		/* recursive? */
+							   false,	/* recursing? */
+							   0		/* expected inhcount */);
+}
+
 /*
  * Execute ALTER TABLE/INDEX/SEQUENCE/VIEW/FOREIGN TABLE RENAME
  */
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 62fde67..1a229a2 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -6713,6 +6713,16 @@ RenameStmt: ALTER AGGREGATE func_name aggr_args RENAME TO name
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			| ALTER TABLE relation_expr RENAME CONSTRAINT name TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_CONSTRAINT;
+					n->relationType = OBJECT_TABLE;
+					n->relation = $3;
+					n->subname = $6;
+					n->newname = $8;
+					$$ = (Node *)n;
+				}
 			| ALTER FOREIGN TABLE relation_expr RENAME opt_column name TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index 03f397d..47b0cdd 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -48,6 +48,8 @@ extern void SetRelationHasSubclass(Oid relationId, bool relhassubclass);
 
 extern void renameatt(RenameStmt *stmt);
 
+extern void RenameConstraint(RenameStmt *stmt);
+
 extern void RenameRelation(RenameStmt *stmt);
 
 extern void RenameRelationInternal(Oid myrelid,
diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 4aba58c..eba0493 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -160,6 +160,141 @@ DROP VIEW tmp_view_new;
 -- toast-like relation name
 alter table stud_emp rename to pg_toast_stud_emp;
 alter table pg_toast_stud_emp rename to stud_emp;
+-- renaming index should rename constraint as well
+ALTER TABLE onek ADD CONSTRAINT onek_unique1_constraint UNIQUE (unique1);
+NOTICE:  ALTER TABLE / ADD UNIQUE will create implicit index "onek_unique1_constraint" for table "onek"
+ALTER INDEX onek_unique1_constraint RENAME TO onek_unique1_constraint_foo;
+ALTER TABLE onek DROP CONSTRAINT onek_unique1_constraint_foo;
+-- renaming constraint
+ALTER TABLE onek ADD CONSTRAINT onek_check_constraint CHECK (unique1 >= 0);
+ALTER TABLE onek RENAME CONSTRAINT onek_check_constraint TO onek_check_constraint_foo;
+ALTER TABLE onek DROP CONSTRAINT onek_check_constraint_foo;
+-- renaming constraint should rename index as well
+ALTER TABLE onek ADD CONSTRAINT onek_unique1_constraint UNIQUE (unique1);
+NOTICE:  ALTER TABLE / ADD UNIQUE will create implicit index "onek_unique1_constraint" for table "onek"
+DROP INDEX onek_unique1_constraint;  -- to see whether it's there
+ERROR:  cannot drop index onek_unique1_constraint because constraint onek_unique1_constraint on table onek requires it
+HINT:  You can drop constraint onek_unique1_constraint on table onek instead.
+ALTER TABLE onek RENAME CONSTRAINT onek_unique1_constraint TO onek_unique1_constraint_foo;
+DROP INDEX onek_unique1_constraint_foo;  -- to see whether it's there
+ERROR:  cannot drop index onek_unique1_constraint_foo because constraint onek_unique1_constraint_foo on table onek requires it
+HINT:  You can drop constraint onek_unique1_constraint_foo on table onek instead.
+ALTER TABLE onek DROP CONSTRAINT onek_unique1_constraint_foo;
+-- renaming constraints vs. inheritance
+CREATE TABLE constraint_rename_test (a int CONSTRAINT con1 CHECK (a > 0), b int, c int);
+\d constraint_rename_test
+Table "public.constraint_rename_test"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+Check constraints:
+    "con1" CHECK (a > 0)
+
+CREATE TABLE constraint_rename_test2 (a int CONSTRAINT con1 CHECK (a > 0), d int) INHERITS (constraint_rename_test);
+NOTICE:  merging column "a" with inherited definition
+NOTICE:  merging constraint "con1" with inherited definition
+\d constraint_rename_test2
+Table "public.constraint_rename_test2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+ d      | integer | 
+Check constraints:
+    "con1" CHECK (a > 0)
+Inherits: constraint_rename_test
+
+ALTER TABLE constraint_rename_test2 RENAME CONSTRAINT con1 TO con1foo; -- fail
+ERROR:  cannot rename inherited constraint "con1"
+ALTER TABLE ONLY constraint_rename_test RENAME CONSTRAINT con1 TO con1foo; -- fail
+ERROR:  inherited constraint "con1" must be renamed in child tables too
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con1 TO con1foo; -- ok
+\d constraint_rename_test
+Table "public.constraint_rename_test"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+Check constraints:
+    "con1foo" CHECK (a > 0)
+Number of child tables: 1 (Use \d+ to list them.)
+
+\d constraint_rename_test2
+Table "public.constraint_rename_test2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+ d      | integer | 
+Check constraints:
+    "con1foo" CHECK (a > 0)
+Inherits: constraint_rename_test
+
+ALTER TABLE ONLY constraint_rename_test ADD CONSTRAINT con2 CHECK (b > 0);
+ALTER TABLE ONLY constraint_rename_test RENAME CONSTRAINT con2 TO con2foo; -- ok
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con2foo TO con2bar; -- ok
+\d constraint_rename_test
+Table "public.constraint_rename_test"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+Check constraints:
+    "con2bar" (ONLY) CHECK (b > 0)
+    "con1foo" CHECK (a > 0)
+Number of child tables: 1 (Use \d+ to list them.)
+
+\d constraint_rename_test2
+Table "public.constraint_rename_test2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+ d      | integer | 
+Check constraints:
+    "con1foo" CHECK (a > 0)
+Inherits: constraint_rename_test
+
+ALTER TABLE constraint_rename_test ADD CONSTRAINT con3 PRIMARY KEY (a);
+NOTICE:  ALTER TABLE / ADD PRIMARY KEY will create implicit index "con3" for table "constraint_rename_test"
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con3 TO con3foo; -- ok
+\d constraint_rename_test
+Table "public.constraint_rename_test"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | not null
+ b      | integer | 
+ c      | integer | 
+Indexes:
+    "con3foo" PRIMARY KEY, btree (a)
+Check constraints:
+    "con2bar" (ONLY) CHECK (b > 0)
+    "con1foo" CHECK (a > 0)
+Number of child tables: 1 (Use \d+ to list them.)
+
+\d constraint_rename_test2
+Table "public.constraint_rename_test2"
+ Column |  Type   | Modifiers 
+--------+---------+-----------
+ a      | integer | 
+ b      | integer | 
+ c      | integer | 
+ d      | integer | 
+Check constraints:
+    "con1foo" CHECK (a > 0)
+Inherits: constraint_rename_test
+
+DROP TABLE constraint_rename_test2;
+DROP TABLE constraint_rename_test;
+ALTER TABLE IF EXISTS constraint_rename_test ADD CONSTRAINT con4 UNIQUE (a);
+NOTICE:  relation "constraint_rename_test" does not exist, skipping
 -- FOREIGN KEY CONSTRAINT adding TEST
 CREATE TABLE tmp2 (a int primary key);
 NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "tmp2_pkey" for table "tmp2"
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index d4e4c49..50c58d2 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -191,6 +191,46 @@ DROP VIEW tmp_view_new;
 alter table stud_emp rename to pg_toast_stud_emp;
 alter table pg_toast_stud_emp rename to stud_emp;
 
+-- renaming index should rename constraint as well
+ALTER TABLE onek ADD CONSTRAINT onek_unique1_constraint UNIQUE (unique1);
+ALTER INDEX onek_unique1_constraint RENAME TO onek_unique1_constraint_foo;
+ALTER TABLE onek DROP CONSTRAINT onek_unique1_constraint_foo;
+
+-- renaming constraint
+ALTER TABLE onek ADD CONSTRAINT onek_check_constraint CHECK (unique1 >= 0);
+ALTER TABLE onek RENAME CONSTRAINT onek_check_constraint TO onek_check_constraint_foo;
+ALTER TABLE onek DROP CONSTRAINT onek_check_constraint_foo;
+
+-- renaming constraint should rename index as well
+ALTER TABLE onek ADD CONSTRAINT onek_unique1_constraint UNIQUE (unique1);
+DROP INDEX onek_unique1_constraint;  -- to see whether it's there
+ALTER TABLE onek RENAME CONSTRAINT onek_unique1_constraint TO onek_unique1_constraint_foo;
+DROP INDEX onek_unique1_constraint_foo;  -- to see whether it's there
+ALTER TABLE onek DROP CONSTRAINT onek_unique1_constraint_foo;
+
+-- renaming constraints vs. inheritance
+CREATE TABLE constraint_rename_test (a int CONSTRAINT con1 CHECK (a > 0), b int, c int);
+\d constraint_rename_test
+CREATE TABLE constraint_rename_test2 (a int CONSTRAINT con1 CHECK (a > 0), d int) INHERITS (constraint_rename_test);
+\d constraint_rename_test2
+ALTER TABLE constraint_rename_test2 RENAME CONSTRAINT con1 TO con1foo; -- fail
+ALTER TABLE ONLY constraint_rename_test RENAME CONSTRAINT con1 TO con1foo; -- fail
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con1 TO con1foo; -- ok
+\d constraint_rename_test
+\d constraint_rename_test2
+ALTER TABLE ONLY constraint_rename_test ADD CONSTRAINT con2 CHECK (b > 0);
+ALTER TABLE ONLY constraint_rename_test RENAME CONSTRAINT con2 TO con2foo; -- ok
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con2foo TO con2bar; -- ok
+\d constraint_rename_test
+\d constraint_rename_test2
+ALTER TABLE constraint_rename_test ADD CONSTRAINT con3 PRIMARY KEY (a);
+ALTER TABLE constraint_rename_test RENAME CONSTRAINT con3 TO con3foo; -- ok
+\d constraint_rename_test
+\d constraint_rename_test2
+DROP TABLE constraint_rename_test2;
+DROP TABLE constraint_rename_test;
+ALTER TABLE IF EXISTS constraint_rename_test ADD CONSTRAINT con4 UNIQUE (a);
+
 -- FOREIGN KEY CONSTRAINT adding TEST
 
 CREATE TABLE tmp2 (a int primary key);