Band aid fix for row visibility issue in output clause (babelfish-for-postgresql#684)

Community commit "Add missing EPQ recheck for TID Scan" breaks babelfish's implementation of output clause as it depends upon self joining the target table for update with itself with ctid in join condition. As a short term fix we are disabling this community fix for babelfish connections and revisit this later on.

Authored-by: Tanzeel Khan tzlkhan@amazon.com
Signed-off-by: Jaspal Singh ijaspals@amazon.com

Issues Resolved
BABEL-6276

Author: jaspal007

src/backend/executor/nodeTidscan.c

@@ -24,6 +24,7 @@
 
 #include "access/sysattr.h"
 #include "access/tableam.h"
+#include "catalog/namespace.h"
 #include "catalog/pg_type.h"
 #include "executor/execdebug.h"
 #include "executor/nodeTidscan.h"
@@ -405,6 +406,13 @@ TidRecheck(TidScanState *node, TupleTableSlot *slot)
 {
 	ItemPointer match;
 
+	/*
+	 * For babelfish skip the EPQ recheck condition in favour of previous
+	 * behaviour as it causes regression to output clause.
+	 */
+	if (is_bbf_tds_connection_hook && is_bbf_tds_connection_hook())
+		return true;
+
 	/* WHERE CURRENT OF always intends to resolve to the latest tuple */
 	if (node->tss_isCurrentOf)
 		return true;