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Have CLUSTER advance the table's relfrozenxid. The new frozen point is the

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FreezeXid introduced in a recent commit, so there isn't any data loss in this
approach.

Doing it causes ALTER TABLE (or rather, the forms of it that cause a full table
rewrite) to be affected as well.  In this case, the frozen point is RecentXmin,
because after the rewrite all the tuples are relabeled with the rewriting
transaction's Xid.

TOAST tables are fixed automatically as well, as fallout of the way they were
already being handled in the respective code paths.

With this patch, there is no longer need to VACUUM tables for Xid wraparound
purposes that have been cleaned up via TRUNCATE or CLUSTER.
This commit is contained in:
Alvaro Herrera
2007-05-18 23:19:42 +00:00
parent 2f1bf8248a
commit b40776d221
3 changed files with 32 additions and 12 deletions
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11
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.224 2007/05/16 17:28:20 alvherre Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.225 2007/05/18 23:19:41 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@ -2285,8 +2285,13 @@ ATRewriteTables(List **wqueue)
*/
ATRewriteTable(tab, OIDNewHeap);
/* Swap the physical files of the old and new heaps. */
swap_relation_files(tab->relid, OIDNewHeap);
/*
* Swap the physical files of the old and new heaps. Since we are
* generating a new heap, we can use RecentXmin for the table's new
* relfrozenxid because we rewrote all the tuples on
* ATRewriteTable, so no older Xid remains on the table.
*/
swap_relation_files(tab->relid, OIDNewHeap, RecentXmin);
CommandCounterIncrement();