Horton

Re: old_snapshot_threshold bottleneck on replica

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Peter Geoghegan <pg@bowt.ie>
Cc: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>, Maxim Orlov <orlovmg@gmail.com>, Postgres hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-09-08T03:48:43Z
Lists: pgsql-hackers

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On Fri, Sep 8, 2023 at 2:00 PM Thomas Munro <thomas.munro@gmail.com> wrote:
> On Fri, Sep 8, 2023 at 1:53 PM Peter Geoghegan <pg@bowt.ie> wrote:
> > Thanks for working on this. Though I wonder why you didn't do
> > something closer to a straight revert of the feature. Why is nbtree
> > still passing around snapshots needlessly?

The code moved around quite a few times over several commits and quite
a lot since then, which is why I didn't go for straight revert, but
clearly the manual approach risked missing things.  I think the
attached removes all unused 'snapshot' arguments from AM-internal
functions.  Checked by compiling with clang's -Wunused-parameters, and
then searching for 'snapshot', and excluding the expected cases.

> > Also, why are there still many comments referencing the feature?
> > There's the one above should_attempt_truncation(), for example.
> > Another appears above init_toast_snapshot(). Are these just
> > oversights, or was it deliberate? You said something about retaining
> > vestiges.

Stray comments removed.

Commits

  1. Remove some more "snapshot too old" vestiges.

  2. Remove the "snapshot too old" feature.