Make CREATE OR REPLACE VIEW internally more consistent

alvherre · alvherre · commit fbef4342a865 · 2015-02-27T19:19:34.000-03:00
The way that columns are added to a view is by calling
AlterTableInternal with special subtype AT_AddColumnToView; but that
subtype is changed to AT_AddColumnRecurse by ATPrepAddColumn.  This has
no visible effect in the current code, since views cannot have
inheritance children (thus the recursion step is a no-op) and adding a
column to a view is executed identically to doing it to a table; but it
does make a difference for future event trigger code keeping track of
commands, because the current situation leads to confusing the case with
a normal ALTER TABLE ADD COLUMN.

Fix the problem by passing a flag to ATPrepAddColumn to prevent it from
changing the command subtype.  The event trigger code can then properly
ignore the subcommand.  (We could remove the call to ATPrepAddColumn,
since views are never typed, and there is never a need for recursion,
which are the two conditions that are checked by ATPrepAddColumn; but it
seems more future-proof to keep the call in place.)
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
@@ -325,7 +325,7 @@ static void ATTypedTableRecursion(List **wqueue, Relation rel, AlterTableCmd *cm
 static List *find_typed_table_dependencies(Oid typeOid, const char *typeName,
 							  DropBehavior behavior);
 static void ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
-				AlterTableCmd *cmd, LOCKMODE lockmode);
+				bool is_view, AlterTableCmd *cmd, LOCKMODE lockmode);
 static void ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 				ColumnDef *colDef, bool isOid,
 				bool recurse, bool recursing, LOCKMODE lockmode);
@@ -3085,14 +3085,16 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 		case AT_AddColumn:		/* ADD COLUMN */
 			ATSimplePermissions(rel,
 						 ATT_TABLE | ATT_COMPOSITE_TYPE | ATT_FOREIGN_TABLE);
-			ATPrepAddColumn(wqueue, rel, recurse, recursing, cmd, lockmode);
+			ATPrepAddColumn(wqueue, rel, recurse, recursing, false, cmd,
+							lockmode);
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
 		case AT_AddColumnToView:		/* add column via CREATE OR REPLACE
 										 * VIEW */
 			ATSimplePermissions(rel, ATT_VIEW);
-			ATPrepAddColumn(wqueue, rel, recurse, recursing, cmd, lockmode);
+			ATPrepAddColumn(wqueue, rel, recurse, recursing, true, cmd,
+							lockmode);
 			/* Recursion occurs during execution phase */
 			pass = AT_PASS_ADD_COL;
 			break;
@@ -4576,7 +4578,7 @@ check_of_type(HeapTuple typetuple)
  */
 static void
 ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
-				AlterTableCmd *cmd, LOCKMODE lockmode)
+				bool is_view, AlterTableCmd *cmd, LOCKMODE lockmode)
 {
 	if (rel->rd_rel->reloftype && !recursing)
 		ereport(ERROR,
@@ -4586,7 +4588,7 @@ ATPrepAddColumn(List **wqueue, Relation rel, bool recurse, bool recursing,
 	if (rel->rd_rel->relkind == RELKIND_COMPOSITE_TYPE)
 		ATTypedTableRecursion(wqueue, rel, cmd, lockmode);
 
-	if (recurse)
+	if (recurse && !is_view)
 		cmd->subtype = AT_AddColumnRecurse;
 }
 
@@ -5026,7 +5028,7 @@ ATPrepAddOids(List **wqueue, Relation rel, bool recurse, AlterTableCmd *cmd, LOC
 		cdef->location = -1;
 		cmd->def = (Node *) cdef;
 	}
-	ATPrepAddColumn(wqueue, rel, recurse, false, cmd, lockmode);
+	ATPrepAddColumn(wqueue, rel, recurse, false, false, cmd, lockmode);
 
 	if (recurse)
 		cmd->subtype = AT_AddOidsRecurse;
