From 06fa6670fb6bf430739cb1f69d28429a0e24851f Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 5 Dec 2016 15:54:28 -0500 Subject: [PATCH] Ensure gatherstate->nextreader is properly initialized. The previously code worked OK as long as a Gather node was never rescanned, or if it was rescanned, as long as it got at least as many workers on rescan as it had originally. But if the number of workers ever decreased on a rescan, then it could crash. Andreas Seltenreich --- src/backend/executor/nodeGather.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c index 438d1b24fc..7342aadfbb 100644 --- a/src/backend/executor/nodeGather.c +++ b/src/backend/executor/nodeGather.c @@ -172,6 +172,7 @@ ExecGather(GatherState *node) if (pcxt->nworkers_launched > 0) { node->nreaders = 0; + node->nextreader = 0; node->reader = palloc(pcxt->nworkers_launched * sizeof(TupleQueueReader *)); @@ -334,6 +335,7 @@ gather_readnext(GatherState *gatherstate) CHECK_FOR_INTERRUPTS(); /* Attempt to read a tuple, but don't block if none is available. */ + Assert(gatherstate->nextreader < gatherstate->nreaders); reader = gatherstate->reader[gatherstate->nextreader]; tup = TupleQueueReaderNext(reader, true, &readerdone); -- 2.40.0