Hello!
Could anyone review patch suggested by Jeff Janes ?
Initial thread
http://www.postgresql.org/message-id/flat/1384356585.995240...@f50.i.mail.ru#1384356585.995240...@f50.i.mail.ru
Thanks in advance!
>
> On Wed, Nov 13, 2013 at 3:53 PM, Sergey Burladyan < eshkin...@gmail.com >
> wrote:
> >Jeff Janes < jeff.ja...@gmail.com > writes:
> >
> >If I not mistaken, looks like lazy_scan_heap() called from lazy_vacuum_rel()
> >(see [1]) skip pages, even if it run with scan_all == true, lazy_scan_heap()
> >does not increment scanned_pages if lazy_check_needs_freeze() return false,
> >so
> >if this occurred at wraparound vacuum it cannot update pg_class, because
> >pg_class updated via this code:
> >
> > new_frozen_xid = FreezeLimit;
> > if (vacrelstats->scanned_pages < vacrelstats->rel_pages)
> > new_frozen_xid = InvalidTransactionId;
> >
> > vac_update_relstats(onerel,
> > new_rel_pages,
> > new_rel_tuples,
> > new_rel_allvisible,
> > vacrelstats->hasindex,
> > new_frozen_xid);
> >
> >so i think in our prevent wraparound vacuum vacrelstats->scanned_pages always
> >less than vacrelstats->rel_pages and pg_class relfrozenxid never updated.
>
> Yeah, I think that that is a bug. If the clean-up lock is unavailable but
> the page is inspected without it and found not to need freezing, then the
> page needs to be counted as scanned, but is not so counted.
>
> commit bbb6e559c4ea0fb4c346beda76736451dc24eb4e
> Date: Mon Nov 7 21:39:40 2011 -0500
>
> But this was introduced in 9.2.0, so unless the OP didn't upgrade to 9.2
> until recently, I don't know why it just started happening.
>
> It looks like a simple fix (to HEAD attached), but I don't know how to test
> it.
>
> Also, it seem like it might be worth issuing a warning if scan_all is true
> but all was not scanned.
>
> Cheers,
>
> Jeff
>
> --
> Sent via pgsql-general mailing list (pgsql-gene...@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general
>
--
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
new file mode 100644
index e1d6d1c..6778c7d
*** a/src/backend/commands/vacuumlazy.c
--- b/src/backend/commands/vacuumlazy.c
*************** lazy_scan_heap(Relation onerel, LVRelSta
*** 602,607 ****
--- 602,608 ----
if (!lazy_check_needs_freeze(buf))
{
UnlockReleaseBuffer(buf);
+ vacrelstats->scanned_pages++;
continue;
}
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
