Horton

Re: Trigger more frequent autovacuums of heavy insert tables

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Pg Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Peter Geoghegan <pg@bowt.ie>, David Rowley <dgrowley@gmail.com>
Date: 2025-02-07T21:05:09Z
Lists: pgsql-hackers 
On Fri, Feb 07, 2025 at 03:57:49PM -0500, Melanie Plageman wrote:
> As for relallfrozen, one of the justifications for adding it to
> pg_class is actually for the visibility it would provide. We have no
> way of knowing how many all-visible but not all-frozen pages there are
> on users' systems without pg_visibility. If users had this
> information, they could potentially tune their freeze-related settings
> more aggressively. Regularly reading the whole visibility map with
> pg_visibilitymap_summary() is pretty hard to justify on most
> production systems. But querying pg_class every 10 minutes or
> something is much more reasonable.

If we need it anyway, then I have no objections to using a freeze-related
metric for a freeze-related feature.

Okay, I'll actually look at the patches next...

-- 
nathan

Commits

  1. doc: Update formula for vacuum insert threshold.

  2. Redefine pg_class.reltuples to be -1 before the first VACUUM or ANALYZE.

  3. Measure the number of all-visible pages for use in index-only scan costing.