Re: Unhappy about API changes in the no-fsm-for-small-rels patch

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-hackers(at)postgresql(dot)org, John Naylor <john(dot)naylor(at)2ndquadrant(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Subject: Re: Unhappy about API changes in the no-fsm-for-small-rels patch
Date: 2019-04-16 18:31:25
Message-ID: 3286.1555439485@sss.pgh.pa.us
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Andres Freund <andres(at)anarazel(dot)de> writes:
> I'm kinda thinking that this is the wrong architecture.

The bits of that patch that I've looked at seemed like a mess
to me too. AFAICT, it's trying to use a single global "map"
for all relations (strike 1) without any clear tracking of
which relation the map currently describes (strike 2).
This can only work at all if an inaccurate map is very fail-soft,
which I'm not convinced it is, and in any case it seems pretty
inefficient for workloads that insert into multiple tables.

I'd have expected any such map to be per-table and be stored in
the relcache.

regards, tom lane

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