From ee7bf0fd9fa7ed4a99e9cf1b9e97409f46a3eb40 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 17 Mar 2018 14:59:31 -0400 Subject: Fix WHERE CURRENT OF when the referenced cursor uses an index-only scan. "UPDATE/DELETE WHERE CURRENT OF cursor_name" failed, with an error message like "cannot extract system attribute from virtual tuple", if the cursor was using a index-only scan for the target table. Fix it by digging the current TID out of the indexscan state. It seems likely that the same failure could occur for CustomScan plans and perhaps some FDW plan types, so that leaving this to be treated as an internal error with an obscure message isn't as good an idea as it first seemed. Hence, add a bit of heaptuple.c infrastructure to let us deliver a more on-topic message. I chose to make the message match what you get for the case where execCurrentOf can't identify the target scan node at all, "cursor "foo" is not a simply updatable scan of table "bar"". Perhaps it should be different, but we can always adjust that later. In the future, it might be nice to provide hooks that would let custom scan providers and/or FDWs deal with this in other ways; but that's not a suitable topic for a back-patchable bug fix. It's been like this all along, so back-patch to all supported branches. Yugo Nagata and Tom Lane Discussion: https://postgr.es/m/20180201013349.937dfc5f.nagata@sraoss.co.jp --- src/include/executor/tuptable.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'src/include/executor') diff --git a/src/include/executor/tuptable.h b/src/include/executor/tuptable.h index 55f4cce4ee1..ec541bb1f0b 100644 --- a/src/include/executor/tuptable.h +++ b/src/include/executor/tuptable.h @@ -169,5 +169,7 @@ extern Datum slot_getattr(TupleTableSlot *slot, int attnum, bool *isnull); extern void slot_getallattrs(TupleTableSlot *slot); extern void slot_getsomeattrs(TupleTableSlot *slot, int attnum); extern bool slot_attisnull(TupleTableSlot *slot, int attnum); +extern bool slot_getsysattr(TupleTableSlot *slot, int attnum, + Datum *value, bool *isnull); #endif /* TUPTABLE_H */ -- cgit v1.2.3