| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com> |
| Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Peter Geoghegan <pg(at)bowt(dot)ie>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Subject: | Re: pg14b1 stuck in lazy_scan_prune/heap_page_prune of pg_statistic |
| Date: | 2021-06-09 18:45:06 |
| Message-ID: | 20210609184506.rqm5rikoikm47csf@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
Hi,
Good find!
On 2021-06-09 17:42:34 +0200, Matthias van de Meent wrote:
> I believe that I've found the culprit:
> GetOldestNonRemovableTransactionId(rel) does not use the exact same
> conditions for returning OldestXmin as GlobalVisTestFor(rel) does.
> This results in different minimal XIDs, and subsequently this failure.
Specifically, the issue is that it uses the innocuous looking
else if (RelationIsAccessibleInLogicalDecoding(rel))
return horizons.catalog_oldest_nonremovable;
but that's not sufficient, because
#define RelationIsAccessibleInLogicalDecoding(relation) \
(XLogLogicalInfoActive() && \
RelationNeedsWAL(relation) && \
(IsCatalogRelation(relation) || RelationIsUsedAsCatalogTable(relation)))
it is never true if wal_level < logical. So what it is missing is the
IsCatalogRelation(rel) || bit.
> The attached patch fixes this inconsistency
I think I prefer applying the fix and the larger changes separately.
> Another approach might be changing GlobalVisTestFor(rel) instead to
> reflect the conditions in GetOldestNonRemovableTransactionId.
No, that'd not be correct, afaict.
Greetings,
Andres Freund
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