On Tue, Jan 09, 2018 at 09:40:50PM +0000, Bossart, Nathan wrote: > On 1/8/18, 10:28 PM, "Michael Paquier" <michael.paqu...@gmail.com> wrote: >> I think that you are doing it wrong here. In get_all_vacuum_rels() you >> should build a RangeVar to be reused in the context of this error >> message, and hence you'll save an extra lookup based on the relation >> OID here, saving from any timing issues that you have overseen as in >> this code path a lock on the relation whose name is looked at is not >> taken. Relying on the RangeVar being NULL to not generate any logs is >> fine as a concept to me, but let's fill it where it is needed, and in >> the case of this patch a VACUUM NOWAIT on the whole database is such a >> case. > > I understand what you are saying here. I think there are two competing > logging behaviors: > > 1. If a relation is concurrently dropped, we should skip logging if > the relation was not specified in the original VACUUM/ANALYZE > command [0] > 2. If a relation is skipped because the lock is not available, we > should never skip logging
At the end this comes back to if the relation is explicitely listed or not in the command specified by the user.. > What do you think? I will take a deeper look into how your suggested > approach might be achieved. Backpedalling a bit on this point and coming back to this message from Tom (https://www.postgresql.org/message-id/28748.1507071576%40sss.pgh.pa.us) which you just cited. Why do we actually need to issue any WARNING messages for unlisted relations? Contrary to what Sawada-san complained upthread, it looks sane to me to not log anything if a relation is not explicitely listed. So you should not get any warnings for a database-wide VACUUM if a relation is dropped while the thing is running, and what you proposed initially in https://www.postgresql.org/message-id/d3fc73e2-9b1a-4db4-8180-55f57d116...@amazon.com is more simple, does not need to worry about any kind of timing issues, and is consistent with autovacuum. -- Michael
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