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Move the tuple freezing point in CLUSTER to a point further back in the past,

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to avoid losing useful Xid information in not-so-old tuples.  This makes
CLUSTER behave the same as VACUUM as far a tuple-freezing behavior goes
(though CLUSTER does not yet advance the table's relfrozenxid).

While at it, move the actual freezing operation in rewriteheap.c to a more
appropriate place, and document it thoroughly.  This part of the patch from
Tom Lane.
This commit is contained in:
Alvaro Herrera
2007-05-17 15:28:29 +00:00
parent 90cbc63fd1
commit 3b0347b36e
6 changed files with 44 additions and 21 deletions
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10
src/backend/commands/vacuum.c
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@@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.350 2007/04/16 18:29:50 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/commands/vacuum.c,v 1.351 2007/05/17 15:28:29 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@@ -566,7 +566,7 @@ get_rel_oids(List *relids, const RangeVar *vacrel, const char *stmttype)
* vacuum_set_xid_limits() -- compute oldest-Xmin and freeze cutoff points
*/
void
vacuum_set_xid_limits(VacuumStmt *vacstmt, bool sharedRel,
vacuum_set_xid_limits(int freeze_min_age, bool sharedRel,
TransactionId *oldestXmin,
TransactionId *freezeLimit)
{
@@ -588,12 +588,12 @@ vacuum_set_xid_limits(VacuumStmt *vacstmt, bool sharedRel,
Assert(TransactionIdIsNormal(*oldestXmin));
/*
* Determine the minimum freeze age to use: as specified in the vacstmt,
* Determine the minimum freeze age to use: as specified by the caller,
* or vacuum_freeze_min_age, but in any case not more than half
* autovacuum_freeze_max_age, so that autovacuums to prevent XID
* wraparound won't occur too frequently.
*/
freezemin = vacstmt->freeze_min_age;
freezemin = freeze_min_age;
if (freezemin < 0)
freezemin = vacuum_freeze_min_age;
freezemin = Min(freezemin, autovacuum_freeze_max_age / 2);
@@ -1154,7 +1154,7 @@ full_vacuum_rel(Relation onerel, VacuumStmt *vacstmt)
i;
VRelStats *vacrelstats;
vacuum_set_xid_limits(vacstmt, onerel->rd_rel->relisshared,
vacuum_set_xid_limits(vacstmt->freeze_min_age, onerel->rd_rel->relisshared,
&OldestXmin, &FreezeLimit);
/*