diff options
Diffstat (limited to 'src/backend/utils/activity/pgstat.c')
| -rw-r--r-- | src/backend/utils/activity/pgstat.c | 36 |
1 files changed, 34 insertions, 2 deletions
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c index b125802b21..f6edfc76ac 100644 --- a/src/backend/utils/activity/pgstat.c +++ b/src/backend/utils/activity/pgstat.c @@ -103,7 +103,7 @@ #include "storage/lwlock.h" #include "storage/pg_shmem.h" #include "storage/shmem.h" -#include "utils/guc.h" +#include "utils/guc_hooks.h" #include "utils/memutils.h" #include "utils/pgstat_internal.h" #include "utils/timestamp.h" @@ -228,6 +228,13 @@ static dlist_head pgStatPending = DLIST_STATIC_INIT(pgStatPending); static bool pgStatForceNextFlush = false; /* + * Force-clear existing snapshot before next use when stats_fetch_consistency + * is changed. + */ +static bool force_stats_snapshot_clear = false; + + +/* * For assertions that check pgstat is not used before initialization / after * shutdown. */ @@ -760,7 +767,8 @@ pgstat_reset_of_kind(PgStat_Kind kind) * request will cause new snapshots to be read. * * This is also invoked during transaction commit or abort to discard - * the no-longer-wanted snapshot. + * the no-longer-wanted snapshot. Updates of stats_fetch_consistency can + * cause this routine to be called. */ void pgstat_clear_snapshot(void) @@ -787,6 +795,9 @@ pgstat_clear_snapshot(void) * forward the reset request. */ pgstat_clear_backend_activity_snapshot(); + + /* Reset this flag, as it may be possible that a cleanup was forced. */ + force_stats_snapshot_clear = false; } void * @@ -885,6 +896,9 @@ pgstat_fetch_entry(PgStat_Kind kind, Oid dboid, Oid objoid) TimestampTz pgstat_get_stat_snapshot_timestamp(bool *have_snapshot) { + if (force_stats_snapshot_clear) + pgstat_clear_snapshot(); + if (pgStatLocal.snapshot.mode == PGSTAT_FETCH_CONSISTENCY_SNAPSHOT) { *have_snapshot = true; @@ -929,6 +943,9 @@ pgstat_snapshot_fixed(PgStat_Kind kind) static void pgstat_prep_snapshot(void) { + if (force_stats_snapshot_clear) + pgstat_clear_snapshot(); + if (pgstat_fetch_consistency == PGSTAT_FETCH_CONSISTENCY_NONE || pgStatLocal.snapshot.stats != NULL) return; @@ -1671,3 +1688,18 @@ pgstat_reset_after_failure(void) /* and drop variable-numbered ones */ pgstat_drop_all_entries(); } + +/* + * GUC assign_hook for stats_fetch_consistency. + */ +void +assign_stats_fetch_consistency(int newval, void *extra) +{ + /* + * Changing this value in a transaction may cause snapshot state + * inconsistencies, so force a clear of the current snapshot on the next + * snapshot build attempt. + */ + if (pgstat_fetch_consistency != newval) + force_stats_snapshot_clear = true; +} |