From f469f0678c3042b8bf96080ccf7cd0aa53468a2d Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 5 Feb 2022 11:59:30 -0500 Subject: [PATCH] Test, don't just Assert, that mergejoin's inputs are in order. There are two Asserts in nodeMergejoin.c that are reachable if the input data is not in the expected order. This seems way too fragile. Alexander Lakhin reported a case where the assertions could be triggered with misconfigured foreign-table partitions, and bitter experience with unstable operating system collation definitions suggests another easy route to hitting them. Neither Assert is in a place where we can't afford one more test-and-branch, so replace 'em with plain test-and-elog logic. Per bug #17395. While the reported symptom is relatively recent, collation changes could happen anytime, so back-patch to all supported branches. Discussion: https://postgr.es/m/17395-8c326292078d1a57@postgresql.org --- src/backend/executor/nodeMergejoin.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/src/backend/executor/nodeMergejoin.c b/src/backend/executor/nodeMergejoin.c index 2a1d000b03..c9c17c805d 100644 --- a/src/backend/executor/nodeMergejoin.c +++ b/src/backend/executor/nodeMergejoin.c @@ -893,11 +893,10 @@ ExecMergeJoin(PlanState *pstate) if (compareResult == 0) node->mj_JoinState = EXEC_MJ_JOINTUPLES; - else - { - Assert(compareResult < 0); + else if (compareResult < 0) node->mj_JoinState = EXEC_MJ_NEXTOUTER; - } + else /* compareResult > 0 should not happen */ + elog(ERROR, "mergejoin input data is out of order"); break; case MJEVAL_NONMATCHABLE: @@ -1087,7 +1086,7 @@ ExecMergeJoin(PlanState *pstate) node->mj_JoinState = EXEC_MJ_JOINTUPLES; } - else + else if (compareResult > 0) { /* ---------------- * if the new outer tuple didn't match the marked inner @@ -1106,7 +1105,6 @@ ExecMergeJoin(PlanState *pstate) * no more inners, no more matches are possible. * ---------------- */ - Assert(compareResult > 0); innerTupleSlot = node->mj_InnerTupleSlot; /* reload comparison data for current inner */ @@ -1140,6 +1138,8 @@ ExecMergeJoin(PlanState *pstate) return NULL; } } + else /* compareResult < 0 should not happen */ + elog(ERROR, "mergejoin input data is out of order"); break; /*----------------------------------------------------------