Horton

Re: Questions/Observations related to Gist vacuum

Heikki Linnakangas <hlinnaka@iki.fi>

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From: Heikki Linnakangas <hlinnaka@iki.fi>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>,PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-10-16T13:51:49Z
Lists: pgsql-hackers 
On 16 October 2019 12:57:03 CEST, Amit Kapila <amit.kapila16@gmail.com> wrote:
>On Tue, Oct 15, 2019 at 7:13 PM Heikki Linnakangas <hlinnaka@iki.fi>
>wrote:
>> All things
>> considered, I'm not sure which is better.
>
>Yeah, this is a tough call to make, but if we can allow it to delete
>the pages in bulkdelete conditionally for parallel vacuum workers,
>then it would be better.

Yeah, if it's needed for parallel vacuum, maybe that tips the scale.

Hopefully, multi-pass vacuums are rare in practice. And we should lift the current 1 GB limit on the dead TID array, replacing it with something more compact and expandable, to make multi-pass vacuums even more rare. So I don't think we need to jump through many hoops to optimize the multi-pass case.

- Heikki

Commits

  1. Delete empty pages in each pass during GIST VACUUM.

  2. Fix memory leak introduced in commit 7df159a620.

  3. Delete empty pages during GiST VACUUM.