Hannu Krosing wrote:
*** src/backend/access/transam/xact.c 28 Apr 2005 21:47:10 -0000 1.200
--- src/backend/access/transam/xact.c 17 May 2005 22:06:34 -0000
***************
*** 1411,1416 ****
--- 1411,1424 ----
AfterTriggerBeginXact();
/*
+ * mark the transaction as not VACUUM (vacuum_rel will set isVacuum to true
+ * directly after calling BeginTransactionCommand() )
+ */
+ if (MyProc != NULL)
+ {
+ MyProc->inVacuum = false;
+ }
I'm a little worried about having this set to "true" after a VACUUM is
executed, and only reset to false when the next transaction is begun: it
shouldn't affect correctness right now, but it seems like asking for
trouble. Resetting the flag to "false" after processing a transaction
would probably be worth doing.
*** src/backend/commands/vacuum.c 6 May 2005 17:24:53 -0000 1.308
--- src/backend/commands/vacuum.c 17 May 2005 22:06:35 -0000
***************
*** 420,425 ****
--- 418,428 ----
if (use_own_xacts)
{
StartTransactionCommand();
+ if (MyProc != NULL) /* is this needed
here ? */
+ {
+ /* so other vacuums don't look
at our xid/xmin in GetOldestXmin() */
+ MyProc->inVacuum = true;
+ }
/* functions in indexes may want a
snapshot set */
ActiveSnapshot =
CopySnapshot(GetTransactionSnapshot());
}
Is it valid to apply this optimization to ANALYZE? Since ANALYZE updates
pg_statistic, ISTM it can affect tuple visibility.
*** src/backend/storage/ipc/sinval.c 31 Dec 2004 22:00:56 -0000 1.75
--- src/backend/storage/ipc/sinval.c 17 May 2005 22:06:36 -0000
***************
*** 845,854 ****
* them as running anyway. We also assume that
such xacts
* can't compute an xmin older than ours, so they
needn't be
* considered in computing globalxmin.
*/
if (proc == MyProc ||
!TransactionIdIsNormal(xid) ||
! TransactionIdFollowsOrEquals(xid, xmax))
continue;
if (TransactionIdPrecedes(xid, xmin))
--- 845,858 ----
* them as running anyway. We also assume that
such xacts
* can't compute an xmin older than ours, so they
needn't be
* considered in computing globalxmin.
+ *
+ * there is also no need to consider transaxtions runnibg the
+ * vacuum command as it will not affect tuple visibility
*/
Typos.
-Neil
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