On 2014-11-01 14:48:20 -0400, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > > On 2014-11-01 14:39:21 -0400, Tom Lane wrote: > >> What exactly do you think is going to make a crashed unlogged index valid > >> again without a REINDEX? Certainly the people who are currently using > >> hash indexes in the way Andrew describes are expecting to have to REINDEX > >> them after a crash. > > > Obviously that individual index needs to be recreated. What I mean is > > that I don't think it'll be acceptable that the table essentially can't > > be queried before that's done. The situations in which I'd found > > unlogged indexes useful is where there's some indexes are critical for > > the OLTP business (those would continue to be logged), but some other > > large ones are for things that aren't absolutely essential. Reports and > > such. > > Sure. And as long as you aren't issuing queries that would want to scan > the crashed index, it won't matter either way. The question is whether > you'd rather that your "inessential reporting queries" fail without the > broken index, or that they take extreme amounts of time/resources. > I don't think it's obvious that the first alternative is bad.
In some of these cases the unlogged index would still be used for a subset of the OLTP workload, e.g. because they're smaller. We e.g. have a client that has smaller (as in 50GB instead of 600GB) indexes for rows of a certain type in the table, but also one that spans the whole thing. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
