postgres.git / summary / log / commit / refs

commit    d13a838e1c19df5358d250b8d469544d7ab3dfda
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Sat Feb 05 16:59:30 2022 +0000

    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 b41454ab6d9..5ff3f4c3a44 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;
 
 				/*----------------------------------------------------------


[parent: ab22eea83169]