Re: Somebody has not thought through subscription locking considerations - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Somebody has not thought through subscription locking considerations
Date
Msg-id 10559.1490981707@sss.pgh.pa.us
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In response to Re: Somebody has not thought through subscription locking considerations  (Masahiko Sawada <sawada.mshk@gmail.com>)
Responses Re: Somebody has not thought through subscription lockingconsiderations  (Petr Jelinek <petr.jelinek@2ndquadrant.com>)
List pgsql-hackers
Masahiko Sawada <sawada.mshk@gmail.com> writes:
> On Fri, Mar 31, 2017 at 9:53 AM, Petr Jelinek
> <petr.jelinek@2ndquadrant.com> wrote:
>> On 30/03/17 07:25, Tom Lane wrote:
>>> I await with interest an explanation of what "VACUUM FULL pg_class" is
>>> doing trying to acquire ShareRowExclusiveLock on pg_subscription_rel, not
>>> to mention why a DROP SEQUENCE is holding some fairly strong lock on that
>>> relation.

> VACUUM FULL of any table acquires ShareRowExclusiveLock on
> pg_subscription_rel because when doDeletion removes old heap the
> RemoveSubscriptionRel is called in heap_drop_with_catalog.

This seems entirely horrid: it *guarantees* deadlock possibilities.
And I wonder what happens when I VACUUM FULL pg_subscription_rel
itself.

At the very least, it would be a good idea to exclude the system
catalogs from logical replication, wouldn't it?
        regards, tom lane



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