On 2014-09-11 13:41:37 -0400, Bruce Momjian wrote:
> > > I agree there - implementing CREATE UNLOGGED INDEX and use THAT for hash
> > > indexes seems like a fairly clean thing to me, hash indexes _are_
> > > unlogged so lets reflect that directly.
> > > I could even envision pg_dump doing that conversion automatically...
> >
> > I think this did came up as a solution before. It's just that nobody
> > found a reasonably easy and clean way to do unlogged indexes on logged
> > tables so far. It's far from trivial.
>
> And practically, how would we implement this for upgrades? Would we have
> pg_dump emit UNLOGGED for any hash creation command?
That seems like an almost trivial problem in comparison to the actual
difficulty of implementing UNLOGGED indexed on LOGGED tables. Yes, I
think forbidding unlogged hash tables + teaching pg_dump a heuristic to
treat any < 9.x hash index as unlogged would be ok.
> That seems to defeat the purpose of this.
Why? It makes hash indexes usable for the cases where it's safe to do
so. Great! It also adds a feature which is really interesting for other
types of indexes.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
