Re: Patch: Write Amplification Reduction Method (WARM)

Pavan Deolasee wrote:
> On Tue, Mar 14, 2017 at 7:17 AM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
> wrote:

> > I didn't like this comment very much. But it's not necessary: you have
> > already given relcache responsibility for setting rd_supportswarm. The
> > only problem seems to be that you set it in RelationGetIndexAttrBitmap
> > instead of RelationGetIndexList, but it's not clear to me why. I think
> > if the latter function is in charge, then we can trust the flag more
> > than the current situation.
>
> I looked at this today. AFAICS we don't have access to rd_amroutine in
> RelationGetIndexList since we don't actually call index_open() in that
> function. Would it be safe to do that? I'll give it a shot, but thought of
> asking here first.

Ah, you're right, we only have the pg_index tuple for the index, not the
pg_am one. I think one pg_am cache lookup isn't really all that
terrible (though we should ensure that there's no circularity problem in
doing that), but I doubt that going to the trouble of invoking the
amhandler just to figure out if it supports WARM is acceptable.

--
Álvaro Herrera https://www.2ndQuadrant.com/
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