Horton

Re: Should vacuum process config file reload more often

Daniel Gustafsson <daniel@yesql.se>

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From: Daniel Gustafsson <daniel@yesql.se>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, John Naylor <john.naylor@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2023-04-27T21:25:30Z
Lists: pgsql-hackers 
> On 27 Apr 2023, at 16:53, Melanie Plageman <melanieplageman@gmail.com> wrote:
> On Thu, Apr 27, 2023 at 8:55 AM Daniel Gustafsson <daniel@yesql.se> wrote:
>> 
>>> On 27 Apr 2023, at 14:10, Masahiko Sawada <sawada.mshk@gmail.com> wrote:

>>> Good catch. I think the problem is that vacuum_rel() is called
>>> recursively and we don't reset VacuumFailsafeActive before vacuuming
>>> the toast table. I think we should reset it in heap_vacuum_rel()
>>> instead of Assert(). It's possible that we trigger the failsafe mode
>>> only for either one.Please find the attached patch.
>> 
>> Agreed, that matches my research and testing, I have the same diff here and it
>> passes testing and works as intended.  This was briefly discussed in [0] and
>> slightly upthread from there but then missed.  I will do some more looking and
>> testing but I'm fairly sure this is the right fix, so unless I find something
>> else I will go ahead with this.
>> 
>> xid_wraparound is a really nifty testing tool. Very cool.Makes sense to me too.
> 
> Fix LGTM.

Thanks for review. I plan to push this in the morning.

> Though we previously set it to false before this series of patches,
> perhaps it is
> worth adding a comment about why VacuumFailsafeActive must be reset here
> even though we reset it before vacuuming each table?

Agreed. 

--
Daniel Gustafsson

Commits

  1. Fix assertion failure in heap_vacuum_rel

  2. Fix vacuum_cost_delay check for balance calculation.

  3. Fix autovacuum cost debug logging

  4. Refresh cost-based delay params more frequently in autovacuum

  5. Separate vacuum cost variables from GUCs

  6. Make vacuum failsafe_active globally visible

  7. Don't balance vacuum cost delay when per-table settings are in effect