On Sun, Aug 22, 2010 at 17:29, Tom Lane <t...@sss.pgh.pa.us> wrote: > Magnus Hagander <mag...@hagander.net> writes: >> I noticed that we were already tracking the information about when an >> autovacuum worker was last started in a database, but this information >> was not exposed. The attached patch puts this column in >> pg_stat_database. > >> Was there any particular reason why this wasn't exposed before that >> I've missed, making this a bad addition? :-) > > I think that's an implementation detail. If we expose it then we'll > be forced to track it forevermore, regardless of whether the AV launcher > actually needs it in the future. (In particular, the assumption that > this is tracked per-database and not per-something-else seems like an > artifact of the current AV launching algorithm.)
That's a good point. OTOH, if we removed the feature, it seems it would be reasonable to remove the column from the statistics view as well. That *could* happen in other stats views as well. > So I'd like to see a positive argument why this is important for users > to know, rather than merely "we should expose every conceivable detail > by default". Why wouldn't a user care more about last AV time for a > specific table, which we already do expose? You need to connect to every database to do that. If you have many databases, that's a lot of overhead particularly if you're doing tihs for regular monitoring. Plus, those views will only track when autovacuum actually *did* something. Being able to see that autovacuum hasn't even touched a database for too long would be an early-indicator that you have some issues with it. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
