Christophe Pettus <xof@thebuild.com> writes:
>> On Oct 9, 2017, at 13:26, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> My bet is that the source server did something that's provoking O(N^2)
>> behavior in the standby server's lock management. It's hard to say
>> exactly what, but I'm wondering about something like a plpgsql function
>> taking an AccessExclusiveLock inside a loop that repeatedly traps an
>> exception. Can you correlate where the standby is stuck with what
>> was happening on the source?
> Interestingly, the OIDs for the relations on which the locks on the secondary are held aren't present in pg_class,
andthey're clustered together. Could a large number of temporary table creations that are being undone by an abort
causethis?
Hmm. Creating or dropping a temp table does take AccessExclusiveLock,
just as it does for a non-temp table. In principle we'd not have to
transmit those locks to standbys, but I doubt that the WAL code has
enough knowledge to filter them out. So a lot of temp tables and
a lot of separate subtransactions could be a nasty combination.
regards, tom lane
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