From 8175a7d11f70589f6b44e28a8dd804f7542d0bbf Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Mon, 7 Oct 2024 14:53:18 +0530 Subject: Fix fetching default toast value during decoding of in-progress transactions. During logical decoding of in-progress transactions, we perform the toast table scan while fetching the default toast value for an attribute. We forgot to initialize the flag during this scan to indicate that the system table scan is in progress. We need this flag to ensure that during logical decoding we never directly access the tableam or heap APIs because we check for concurrent aborts only in systable_* APIs. Reported-by: Alexander Lakhin Author: Takeshi Ideriha, Hou Zhijie Reviewed-by: Amit Kapila, Hou Zhijie Backpatch-through: 14 Discussion: https://postgr.es/m/18641-6687273b7f15269d@postgresql.org --- src/backend/access/index/genam.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'src') diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c index ede9660c9eb..76d3edd470e 100644 --- a/src/backend/access/index/genam.c +++ b/src/backend/access/index/genam.c @@ -703,6 +703,14 @@ systable_beginscan_ordered(Relation heapRelation, index_rescan(sysscan->iscan, key, nkeys, NULL, 0); sysscan->scan = NULL; + /* + * If CheckXidAlive is set then set a flag to indicate that system table + * scan is in-progress. See detailed comments in xact.c where these + * variables are declared. + */ + if (TransactionIdIsValid(CheckXidAlive)) + bsysscan = true; + return sysscan; } @@ -747,6 +755,14 @@ systable_endscan_ordered(SysScanDesc sysscan) index_endscan(sysscan->iscan); if (sysscan->snapshot) UnregisterSnapshot(sysscan->snapshot); + + /* + * Reset the bsysscan flag at the end of the systable scan. See detailed + * comments in xact.c where these variables are declared. + */ + if (TransactionIdIsValid(CheckXidAlive)) + bsysscan = false; + pfree(sysscan); } -- cgit v1.2.3