Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <

From: Kevin Grittner <kgrittn(at)gmail(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Noah Misch <noah(at)leadboat(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Ants Aasma <ants(dot)aasma(at)eesti(dot)ee>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)postgresql(dot)org>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: [COMMITTERS] pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <
Date: 2016-07-08 16:00:50
Message-ID: CACjxUsPR+fr5QeYJMpPqvP3HyPDYynWa6NsFoivox7ViHxVD9Q@mail.gmail.com
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On Wed, Jul 6, 2016 at 4:55 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:

> So I don't think that approach still allows old snapshot related
> cleanups for toast triggered vacuums? Is that an acceptable
> restriction?

What I would rather see is that if the heap is vacuumed (whether or
not by autovacuum) then the related TOAST table is also vacuumed
(using the same horizon the heap used), but if the TOAST relation
is chosen for vacuum by itself that it does not attempt to adjust
the horizon based on old_snapshot_threshold. I am looking to see
how to make that happen; expect a new patch Monday.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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