diff options
Diffstat (limited to 'src/backend/commands/vacuum.c')
| -rw-r--r-- | src/backend/commands/vacuum.c | 32 |
1 files changed, 14 insertions, 18 deletions
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index 65aacb99e2f..6e58d561e89 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -13,7 +13,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.342.2.5 2008/02/11 19:14:38 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.342.2.6 2008/09/11 14:01:16 alvherre Exp $ * *------------------------------------------------------------------------- */ @@ -764,14 +764,12 @@ vac_update_datfrozenxid(void) bool dirty = false; /* - * Initialize the "min" calculation with RecentGlobalXmin. Any - * not-yet-committed pg_class entries for new tables must have - * relfrozenxid at least this high, because any other open xact must have - * RecentXmin >= its PGPROC.xmin >= our RecentGlobalXmin; see - * AddNewRelationTuple(). So we cannot produce a wrong minimum by - * starting with this. + * Initialize the "min" calculation with GetOldestXmin, which is a + * reasonable approximation to the minimum relfrozenxid for not-yet- + * committed pg_class entries for new tables; see AddNewRelationTuple(). + * Se we cannot produce a wrong minimum by starting with this. */ - newFrozenXid = RecentGlobalXmin; + newFrozenXid = GetOldestXmin(true, true); /* * We must seqscan pg_class to find the minimum Xid, because there is no @@ -965,18 +963,16 @@ vacuum_rel(Oid relid, VacuumStmt *vacstmt, char expected_relkind) /* Begin a transaction for vacuuming this relation */ StartTransactionCommand(); - if (vacstmt->full) - { - /* functions in indexes may want a snapshot set */ - ActiveSnapshot = CopySnapshot(GetTransactionSnapshot()); - } - else + /* + * Functions in indexes may want a snapshot set. Also, setting + * a snapshot ensures that RecentGlobalXmin is kept truly recent. + */ + ActiveSnapshot = CopySnapshot(GetTransactionSnapshot()); + + if (!vacstmt->full) { /* - * During a lazy VACUUM we do not run any user-supplied functions, and - * so it should be safe to not create a transaction snapshot. - * - * We can furthermore set the inVacuum flag, which lets other + * During a lazy VACUUM we can set the inVacuum flag, which lets other * concurrent VACUUMs know that they can ignore this one while * determining their OldestXmin. (The reason we don't set inVacuum * during a full VACUUM is exactly that we may have to run user- |