From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Shared access methods? |
Date: | 2018-06-14 20:33:08 |
Message-ID: | 20180614203308.z5avlahwlrsixd23@alvherre.pgsql |
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Lists: | pgsql-hackers |
On 2018-Jun-14, Andres Freund wrote:
> But I do think there's a few things that are doable without actually
> needing to invoke any user defined code aside of the AM code
> itself. E.g. heap pruning / aggressively setting hint bits doesn't need
> to invoke operators, and I can think of some ways to implement index
> delete marking that does so without invoking any comparators either.
So what you want to do is have bgwriter/checkpointer able to scan some
catalog and grab a function pointer that can "execute pruning on this
shared buffer", right? For that maybe we need to split out a part of
AMs that is storage-level and another one that is data-level. So an
access method would create two catalog entries, one of which is shared
(pg_shared_am? ugh) and the other is the regular one we already have in
pg_am. The handler function in pg_shared_am gives you functions that
can only do storage-level stuff such as hint bit setting, page pruning,
tuple freezing, CRC, etc which does not require access to the data
itself.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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