postgres.git / summary / log / commit / refs

commit    1e468ea4eace4ba150535fba9c752d9ea61e2bdf
Author:   Tomas Vondra <tomas.vondra@postgresql.org>
Date:     Sun Nov 19 20:03:29 2023 +0000
First released in: 17.0, 12.18, 13.14, 14.11, 15.6, 16.2

    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 39aab1c1f0b..f3a6c2e7cc0 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -538,20 +538,14 @@ AlterStatistics(AlterStatsStmt *stmt)
 }
 
 /*
- * Guts of statistics object deletion.
- */
-void
-RemoveStatisticsById(Oid statsOid)
+* Guts of statistics object deletion.
+*/
+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));
@@ -564,6 +558,19 @@ 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
@@ -579,12 +586,24 @@ 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);
 }
 


[parent: b736f06ccfa6]