Re: pg15b2: large objects lost on upgrade - Mailing list pgsql-hackers

From Robert Haas
Subject Re: pg15b2: large objects lost on upgrade
Date
Msg-id CA+TgmoastyZUAmJ6t953=yycQxu_S0x6A08QVARsbOVAWW=D2A@mail.gmail.com
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In response to Re: pg15b2: large objects lost on upgrade  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: pg15b2: large objects lost on upgrade
List pgsql-hackers
On Tue, Aug 2, 2022 at 1:12 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Not sure what to make of this, except that maybe the test is telling
> us about an actual bug of exactly the kind it's designed to expose.

That could be, but what would the bug be exactly? It's hard to think
of a more direct way of setting relminmxid and relfrozenxid than
updating pg_class. It doesn't seem realistic to suppose that we have a
bug where setting a column in a system table to an integer value
sometimes sets it to a slightly larger integer instead. If the values
on the new cluster seemed like they had never been set, or if it
seemed like they had been set to completely random values, then I'd
suspect a bug in the mechanism, but here it seems more believable to
me to think that we're actually setting the correct values and then
something - maybe autovacuum - bumps them again before we have a
chance to look at them.

I'm not quite sure how to rule that theory in or out, though.

-- 
Robert Haas
EDB: http://www.enterprisedb.com



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