| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Noah Misch <noah(at)leadboat(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Incomplete freezing when truncating a relation during vacuum |
| Date: | 2013-12-01 23:02:27 |
| Message-ID: | 7692.1385938947@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)2ndquadrant(dot)com> writes:
> On 2013-12-01 17:15:31 -0500, Tom Lane wrote:
>> Is there really a significant risk of clog access errors due to this bug?
>> IIUC, the risk is that tuples in pages that vacuum skips due to being
>> all-visible might not be frozen when intended.
> Unfortunately it's not actually too hard to hit due to following part of the
> code in vacuumlazy.c:
> /*
> * If we're not scanning the whole relation to guard against XID
> * wraparound, it's OK to skip vacuuming a page. The next vacuum
> * will clean it up.
> */
Ah. So it's only been *seriously* broken since commit bbb6e559c, ie 9.2.
regards, tom lane
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