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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2020-03-31 17:06:22 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2020-03-31 17:06:22 -0400 |
| commit | 6c426cd43790d56e6b96c21ae2d968ceb733bdde (patch) | |
| tree | 33c27afccf1ff9c5cd4329d6979c8682aa81c3f0 | |
| parent | 1fd0eee66f1e74d6a547d860a9f5d51a2277bb02 (diff) | |
| download | postgresql-6c426cd43790d56e6b96c21ae2d968ceb733bdde.tar.gz postgresql-6c426cd43790d56e6b96c21ae2d968ceb733bdde.zip | |
Fix race condition in statext_store().
Must hold some lock on the pg_statistic_ext_data catalog *before*
we look up the tuple we aim to replace. Otherwise a concurrent
VACUUM FULL or similar operation could move it to a different TID,
leaving us trying to replace the wrong tuple.
Back-patch to v12 where this got broken.
Credit goes to Dean Rasheed; I'm just doing the clerical work.
Discussion: https://postgr.es/m/CAEZATCU0zHMDiQV0g8P2U+YSP9C1idUPrn79DajsbonwkN0xvQ@mail.gmail.com
| -rw-r--r-- | src/backend/statistics/extended_stats.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c index 4516c97f406..d8e51500232 100644 --- a/src/backend/statistics/extended_stats.c +++ b/src/backend/statistics/extended_stats.c @@ -322,12 +322,14 @@ statext_store(Oid statOid, MVNDistinct *ndistinct, MVDependencies *dependencies, MCVList *mcv, VacAttrStats **stats) { + Relation pg_stextdata; HeapTuple stup, oldtup; Datum values[Natts_pg_statistic_ext_data]; bool nulls[Natts_pg_statistic_ext_data]; bool replaces[Natts_pg_statistic_ext_data]; - Relation pg_stextdata; + + pg_stextdata = table_open(StatisticExtDataRelationId, RowExclusiveLock); memset(nulls, true, sizeof(nulls)); memset(replaces, false, sizeof(replaces)); @@ -371,8 +373,6 @@ statext_store(Oid statOid, elog(ERROR, "cache lookup failed for statistics object %u", statOid); /* replace it */ - pg_stextdata = table_open(StatisticExtDataRelationId, RowExclusiveLock); - stup = heap_modify_tuple(oldtup, RelationGetDescr(pg_stextdata), values, |