Horton

RE: reloption to prevent VACUUM from truncating empty pages at the end of relation

Tsunakawa, Takayuki <tsunakawa.takay@jp.fujitsu.com>

View thread
From: "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>
To: 'Alvaro Herrera' <alvherre@2ndquadrant.com>, 'Andres Freund' <andres@anarazel.de>, Fujii Masao <masao.fujii@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Julien Rouhaud <rjuju123@gmail.com>, David Steele <david@pgmasters.net>, "Bossart, Nathan" <bossartn@amazon.com>, "Andrew Dunstan" <andrew.dunstan@2ndquadrant.com>, Michael Paquier <michael@paquier.xyz>, Laurenz Albe <laurenz.albe@cybertec.at>, "Jamison, Kirk" <k.jamison@jp.fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-04-08T05:22:17Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add TRUNCATE parameter to VACUUM.

  2. Add vacuum_truncate reloption.

  3. Allow VACUUM to be run with index cleanup disabled.

From: Alvaro Herrera [mailto:alvherre@2ndquadrant.com]
> "vacuum_truncate" gets my vote too.

+1


From: 'Andres Freund' [mailto:andres@anarazel.de]
> Personally I think the name just needs some committer to make a
> call. This largely is going to be used after encountering too many
> cancellations in production, and researching the cause. Minor spelling
> differences don't seem to particularly matter here.

Absolutely.  Thank you.


From: 'Andres Freund' [mailto:andres@anarazel.de]
> I think it needs to be an autovac option. The production issue is that
> autovacuums constantly cancel queries on the standbys despite
> hot_standby_feedback if you have a workload that does frequent
> truncations. If there's no way to configure it in a way that autovacuum
> takes it into account, people will just disable autovacuum and rely
> entirely on manual scripts. That's what already happens - leading to a
> much bigger foot-gun than disabling truncation.  FWIW, people already in
> production use the workaround to configuring snapshot_too_old as that,
> for undocumented reasons, disables trunctations. That's not better
> either.

Right.  We don't want autovacuum to be considered as a criminal.


Regards
Takayuki Tsunakawa