From 9dd50e92ed239bc4643c1df7e9e0bcc03b05bfef Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.vondra@postgresql.org>
Date: Sun, 19 Nov 2023 21:03:29 +0100
Subject: [PATCH] Lock table in DROP STATISTICS
The DROP STATISTICS code failed to properly lock the table, leading to
ERROR: tuple concurrently deleted
when executed concurrently with ANALYZE.
Fixed by modifying RemoveStatisticsById() to acquire the same lock as
ANALYZE. This function is called only by DROP STATISTICS, as ANALYZE
calls RemoveStatisticsDataById() directly.
Reported by Justin Pryzby, fix by me. Backpatch through 12. The code was
like this since it was introduced in 10, but older releases are EOL.
Reported-by: Justin Pryzby
Reviewed-by: Tom Lane
Backpatch-through: 12
Discussion: https://postgr.es/m/ZUuk-8CfbYeq6g_u@pryzbyj2023
---
src/backend/commands/statscmds.c | 39 ++++++++++++++++++++++++--------
1 file changed, 29 insertions(+), 10 deletions(-)
diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index 6d8f4822b46..df6cb4a6f49 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -722,20 +722,14 @@ AlterStatistics(AlterStatsStmt *stmt)
}
/*
- * Guts of statistics object deletion.
- */
-void
-RemoveStatisticsById(Oid statsOid)
+ * Delete entry in pg_statistic_ext_data catalog.
+*/
+static void
+RemoveStatisticsDataById(Oid statsOid)
{
Relation relation;
HeapTuple tup;
- Form_pg_statistic_ext statext;
- Oid relid;
- /*
- * First delete the pg_statistic_ext_data tuple holding the actual
- * statistical data.
- */
relation = table_open(StatisticExtDataRelationId, RowExclusiveLock);
tup = SearchSysCache1(STATEXTDATASTXOID, ObjectIdGetDatum(statsOid));
@@ -748,6 +742,19 @@ RemoveStatisticsById(Oid statsOid)
ReleaseSysCache(tup);
table_close(relation, RowExclusiveLock);
+}
+
+/*
+ * Guts of statistics object deletion.
+ */
+void
+RemoveStatisticsById(Oid statsOid)
+{
+ Relation relation;
+ Relation rel;
+ HeapTuple tup;
+ Form_pg_statistic_ext statext;
+ Oid relid;
/*
* Delete the pg_statistic_ext tuple. Also send out a cache inval on the
@@ -763,12 +770,24 @@ RemoveStatisticsById(Oid statsOid)
statext = (Form_pg_statistic_ext) GETSTRUCT(tup);
relid = statext->stxrelid;
+ /*
+ * Delete the pg_statistic_ext_data tuple holding the actual statistical
+ * data. We lock the user table first, to prevent other processes (e.g.
+ * DROP STATISTICS) from removing the row concurrently.
+ */
+ rel = table_open(relid, ShareUpdateExclusiveLock);
+
+ RemoveStatisticsDataById(statsOid);
+
CacheInvalidateRelcacheByRelid(relid);
CatalogTupleDelete(relation, &tup->t_self);
ReleaseSysCache(tup);
+ /* Keep lock until the end of the transaction. */
+ table_close(rel, NoLock);
+
table_close(relation, RowExclusiveLock);
}
--
2.39.5