Horton

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

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: Andres Freund <andres@anarazel.de>
Cc: Peter Geoghegan <pg@bowt.ie>, pgsql-hackers@postgresql.org, Robert Haas <robertmhaas@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>, David Rowley <dgrowleyml@gmail.com>
Date: 2023-01-11T20:38:34Z
Lists: pgsql-hackers 
On Wed, Jan 11, 2023 at 10:58:54AM -0800, Andres Freund wrote:
> Hi,
> 
> On 2023-01-11 10:35:19 -0800, Peter Geoghegan wrote:
> > On Wed, Jan 11, 2023 at 10:27 AM Andres Freund <andres@anarazel.de> wrote:
> > > Therefore I'd like to add an option to the VACUUM command to use to disable
> > > the use of the ringbuffer. Not sure about the name yet.
> > 
> > Sounds like a good idea.
> 
> Any idea about the name? The obvious thing is to reference ring buffers in the
> option name, but that's more of an implementation detail...
> 
> Some ideas:
> 
> USE_RING_BUFFERS on|off
> REUSE_BUFFERS on|off

+1 for either of these.

I don't think it's an issue to expose implementation details here.
Anyone who wants to change this will know about the implementation
details that they're changing, and it's better to refer to it by the
same/similar name and not by some other name that's hard to find.

BTW I can't see that the ring buffer is currently exposed in any
user-facing docs for COPY/ALTER/VACUUM/CREATE ?

-- 
Justin

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