Horton

Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode

Melanie Plageman <melanieplageman@gmail.com>

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From: Melanie Plageman <melanieplageman@gmail.com>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Justin Pryzby <pryzby@telsasoft.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>, Peter Geoghegan <pg@bowt.ie>, pgsql-hackers@postgresql.org, Robert Haas <robertmhaas@gmail.com>
Date: 2023-03-31T23:57:36Z
Lists: pgsql-hackers

Attachments

On Fri, Mar 31, 2023 at 5:47 PM David Rowley <dgrowleyml@gmail.com> wrote:
>
> On Sat, 1 Apr 2023 at 02:52, Melanie Plageman <melanieplageman@gmail.com> wrote:
> > There was one small typo keeping this from compiling. Also a repeated
> > word. I've fixed these. I also edited a bit of indentation and tweaked
> > some wording. Diff attached (to be applied on top of your diff).
>
> Thanks for fixing that mistake.
>
> For reference, I had changed things to end lines early so that the
> glossterm tags could be on a line of their own without breaking to a
> new line. The rest of the file seems to be done that way, so I thought
> we'd better stick to it.
>
> I swapped out "associated WAL" for "unflushed WAL". I didn't agree
> that the WAL that would be flushed would have any particular
> association with the to-be-written page.
>
> I dropped CTAS since I didn't see any other mention in the docs about
> that. I could maybe see the sense in making reference to the
> abbreviated form if we were going to mention it again and didn't want
> to spell the whole thing out each time, but that's not the case here.
>
> I pushed the result.

Cool!

I've attached v7 with that commit dropped and with support for parallel
vacuum workers to use the same number of buffers in their own Buffer
Access Strategy ring as the main vacuum phase did. I also updated the
docs to indicate that vacuum_buffer_usage_limit is per backend (not per
instance of VACUUM).

- Melanie

Commits

  1. Add unit to vacuum_buffer_usage_limit value in postgresql.conf.sample.

  2. Improve VACUUM/ANALYZE BUFFER_USAGE_LIMIT docs

  3. Add --buffer-usage-limit option to vacuumdb

  4. Add VACUUM/ANALYZE BUFFER_USAGE_LIMIT option

  5. Move various prechecks from vacuum() into ExecVacuum()

  6. Always make a BufferAccessStrategy for ANALYZE

  7. Rename BufferAccessStrategyData.ring_size to nbuffers

  8. Disable vacuum's use of a buffer access strategy during failsafe

  9. Only make buffer strategy for vacuum when it's likely needed

  10. Remove some global variables from vacuum.c

  11. Doc: add Buffer Access Strategy to the glossary