diff options
| author | Tom Lane | 2006-11-05 22:42:10 +0000 |
|---|---|---|
| committer | Tom Lane | 2006-11-05 22:42:10 +0000 |
| commit | 48188e1621bb6711e7d092bee48523b18cd80177 (patch) | |
| tree | 524459ab58f8740a23efa7b7b521833646c678ba /src/backend/utils/time | |
| parent | 10c70b86023001dc6d9028737afc97850b86e58f (diff) | |
Fix recently-understood problems with handling of XID freezing, particularly
in PITR scenarios. We now WAL-log the replacement of old XIDs with
FrozenTransactionId, so that such replacement is guaranteed to propagate to
PITR slave databases. Also, rather than relying on hint-bit updates to be
preserved, pg_clog is not truncated until all instances of an XID are known to
have been replaced by FrozenTransactionId. Add new GUC variables and
pg_autovacuum columns to allow management of the freezing policy, so that
users can trade off the size of pg_clog against the amount of freezing work
done. Revise the already-existing code that forces autovacuum of tables
approaching the wraparound point to make it more bulletproof; also, revise the
autovacuum logic so that anti-wraparound vacuuming is done per-table rather
than per-database. initdb forced because of changes in pg_class, pg_database,
and pg_autovacuum catalogs. Heikki Linnakangas, Simon Riggs, and Tom Lane.
Diffstat (limited to 'src/backend/utils/time')
| -rw-r--r-- | src/backend/utils/time/tqual.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/src/backend/utils/time/tqual.c b/src/backend/utils/time/tqual.c index eedc6222be8..2bdb6d9e714 100644 --- a/src/backend/utils/time/tqual.c +++ b/src/backend/utils/time/tqual.c @@ -32,7 +32,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/time/tqual.c,v 1.98 2006/10/04 00:30:04 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/utils/time/tqual.c,v 1.99 2006/11/05 22:42:09 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1099,9 +1099,11 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin, { /* * "Deleting" xact really only locked it, so the tuple is live in any - * case. However, we must make sure that either XMAX_COMMITTED or - * XMAX_INVALID gets set once the xact is gone; otherwise it is unsafe - * to recycle CLOG status after vacuuming. + * case. However, we should make sure that either XMAX_COMMITTED or + * XMAX_INVALID gets set once the xact is gone, to reduce the costs + * of examining the tuple for future xacts. Also, marking dead + * MultiXacts as invalid here provides defense against MultiXactId + * wraparound (see also comments in heap_freeze_tuple()). */ if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED)) { |