1 files changed, 50 insertions, 16 deletions

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 54ad38247aa..ea96947d813 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -430,8 +430,8 @@ static void AlterConstrUpdateConstraintEntry(ATAlterConstraint *cmdcon, Relation
 static ObjectAddress ATExecValidateConstraint(List **wqueue,
 											  Relation rel, char *constrName,
 											  bool recurse, bool recursing, LOCKMODE lockmode);
-static void QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
-										HeapTuple contuple, LOCKMODE lockmode);
+static void QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation fkrel,
+										Oid pkrelid, HeapTuple contuple, LOCKMODE lockmode);
 static void QueueCheckConstraintValidation(List **wqueue, Relation conrel, Relation rel,
 										   char *constrName, HeapTuple contuple,
 										   bool recurse, bool recursing, LOCKMODE lockmode);
@@ -11858,6 +11858,7 @@ AttachPartitionForeignKey(List **wqueue,
 	if (queueValidation)
 	{
 		Relation	conrel;
+		Oid			confrelid;
 
 		conrel = table_open(ConstraintRelationId, RowExclusiveLock);
 
@@ -11865,9 +11866,11 @@ AttachPartitionForeignKey(List **wqueue,
 		if (!HeapTupleIsValid(partcontup))
 			elog(ERROR, "cache lookup failed for constraint %u", partConstrOid);
 
+		confrelid = ((Form_pg_constraint) GETSTRUCT(partcontup))->confrelid;
+
 		/* Use the same lock as for AT_ValidateConstraint */
-		QueueFKConstraintValidation(wqueue, conrel, partition, partcontup,
-									ShareUpdateExclusiveLock);
+		QueueFKConstraintValidation(wqueue, conrel, partition, confrelid,
+									partcontup, ShareUpdateExclusiveLock);
 		ReleaseSysCache(partcontup);
 		table_close(conrel, RowExclusiveLock);
 	}
@@ -12463,9 +12466,12 @@ ATExecAlterConstrEnforceability(List **wqueue, ATAlterConstraint *cmdcon,
 
 		/*
 		 * Tell Phase 3 to check that the constraint is satisfied by existing
-		 * rows.
+		 * rows.  Only applies to leaf partitions, and (for constraints that
+		 * reference a partitioned table) only if this is not one of the
+		 * pg_constraint rows that exist solely to support action triggers.
 		 */
-		if (rel->rd_rel->relkind == RELKIND_RELATION)
+		if (rel->rd_rel->relkind == RELKIND_RELATION &&
+			currcon->confrelid == pkrelid)
 		{
 			AlteredTableInfo *tab;
 			NewConstraint *newcon;
@@ -12919,7 +12925,8 @@ ATExecValidateConstraint(List **wqueue, Relation rel, char *constrName,
 	{
 		if (con->contype == CONSTRAINT_FOREIGN)
 		{
-			QueueFKConstraintValidation(wqueue, conrel, rel, tuple, lockmode);
+			QueueFKConstraintValidation(wqueue, conrel, rel, con->confrelid,
+										tuple, lockmode);
 		}
 		else if (con->contype == CONSTRAINT_CHECK)
 		{
@@ -12952,8 +12959,8 @@ ATExecValidateConstraint(List **wqueue, Relation rel, char *constrName,
  * for the specified relation and all its children.
  */
 static void
-QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
-							HeapTuple contuple, LOCKMODE lockmode)
+QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation fkrel,
+							Oid pkrelid, HeapTuple contuple, LOCKMODE lockmode)
 {
 	Form_pg_constraint con;
 	AlteredTableInfo *tab;
@@ -12964,7 +12971,17 @@ QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
 	Assert(con->contype == CONSTRAINT_FOREIGN);
 	Assert(!con->convalidated);
 
-	if (rel->rd_rel->relkind == RELKIND_RELATION)
+	/*
+	 * Add the validation to phase 3's queue; not needed for partitioned
+	 * tables themselves, only for their partitions.
+	 *
+	 * When the referenced table (pkrelid) is partitioned, the referencing
+	 * table (fkrel) has one pg_constraint row pointing to each partition
+	 * thereof.  These rows are there only to support action triggers and no
+	 * table scan is needed, therefore skip this for them as well.
+	 */
+	if (fkrel->rd_rel->relkind == RELKIND_RELATION &&
+		con->confrelid == pkrelid)
 	{
 		NewConstraint *newcon;
 		Constraint *fkconstraint;
@@ -12983,15 +13000,16 @@ QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
 		newcon->qual = (Node *) fkconstraint;
 
 		/* Find or create work queue entry for this table */
-		tab = ATGetQueueEntry(wqueue, rel);
+		tab = ATGetQueueEntry(wqueue, fkrel);
 		tab->constraints = lappend(tab->constraints, newcon);
 	}
 
 	/*
 	 * If the table at either end of the constraint is partitioned, we need to
-	 * recurse and handle every constraint that is a child of this constraint.
+	 * recurse and handle every unvalidate constraint that is a child of this
+	 * constraint.
 	 */
-	if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
+	if (fkrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ||
 		get_rel_relkind(con->confrelid) == RELKIND_PARTITIONED_TABLE)
 	{
 		ScanKeyData pkey;
@@ -13023,8 +13041,12 @@ QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
 
 			childrel = table_open(childcon->conrelid, lockmode);
 
-			QueueFKConstraintValidation(wqueue, conrel, childrel, childtup,
-										lockmode);
+			/*
+			 * NB: Note that pkrelid should be passed as-is during recursion,
+			 * as it is required to identify the root referenced table.
+			 */
+			QueueFKConstraintValidation(wqueue, conrel, childrel, pkrelid,
+										childtup, lockmode);
 			table_close(childrel, NoLock);
 		}
 
@@ -13032,7 +13054,11 @@ QueueFKConstraintValidation(List **wqueue, Relation conrel, Relation rel,
 	}
 
 	/*
-	 * Now update the catalog, while we have the door open.
+	 * Now mark the pg_constraint row as validated (even if we didn't check,
+	 * notably the ones for partitions on the referenced side).
+	 *
+	 * We rely on transaction abort to roll back this change if phase 3
+	 * ultimately finds violating rows.  This is a bit ugly.
 	 */
 	copyTuple = heap_copytuple(contuple);
 	copy_con = (Form_pg_constraint) GETSTRUCT(copyTuple);
@@ -20964,9 +20990,17 @@ ATExecDetachPartition(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		tab->rel = rel;
 	}
 
+	/*
+	 * Detaching the partition might involve TOAST table access, so ensure we
+	 * have a valid snapshot.
+	 */
+	PushActiveSnapshot(GetTransactionSnapshot());
+
 	/* Do the final part of detaching */
 	DetachPartitionFinalize(rel, partRel, concurrent, defaultPartOid);
 
+	PopActiveSnapshot();
+
 	ObjectAddressSet(address, RelationRelationId, RelationGetRelid(partRel));
 
 	/* keep our lock until commit */