special_case_CHECK_parent.patch

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 82bb756..5340402 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -5433,6 +5433,7 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	ListCell   *lcon;
 	List	   *children;
 	ListCell   *child;
+	bool		skip_children = false;
 
 	/* At top level, permission check was done in ATPrepCmd, else do it */
 	if (recursing)
@@ -5502,9 +5503,31 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	 * tables; else the addition would put them out of step.
 	 */
 	if (children && !recurse)
-		ereport(ERROR,
+	{
+		/*
+		 * Try a bit harder and check if this is a CHECK(FALSE) kinda
+		 * constraint. Allow if so, otherwise error out
+		 */
+		if (list_length(newcons) == 1)
+		{
+			CookedConstraint *cooked = linitial(newcons);
+
+			if (cooked->contype == CONSTR_CHECK && cooked->expr)
+			{
+				Node *expr = cooked->expr;
+				if (IsA(expr, Const) && ((Const *)expr)->consttype == BOOLOID &&
+					 ((Const *)expr)->constvalue == 0)
+				{
+					skip_children = true;
+				}
+			}
+		}
+
+		if (!skip_children)
+			ereport(ERROR,
 				(errcode(ERRCODE_INVALID_TABLE_DEFINITION),
 				 errmsg("constraint must be added to child tables too")));
+	}
 
 	foreach(child, children)
 	{
@@ -5512,6 +5535,13 @@ ATAddCheckConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		Relation	childrel;
 		AlteredTableInfo *childtab;
 
+		/*
+		 * Skipping the constraint should be good enough for the special case.
+		 * No need to even release the locks on the children immediately..
+		 */
+		if (skip_children)
+			break;
+
 		/* find_inheritance_children already got lock */
 		childrel = heap_open(childrelid, NoLock);
 		CheckTableNotInUse(childrel, "ALTER TABLE");