Horton

Re: Confine vacuum skip logic to lazy_scan_skip

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, vignesh C <vignesh21@gmail.com>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>, Thomas Munro <thomas.munro@gmail.com>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Robert Haas <robertmhaas@gmail.com>
Date: 2024-03-08T16:06:56Z
Lists: pgsql-hackers 
On Fri, Mar 8, 2024 at 11:00 AM Peter Geoghegan <pg@bowt.ie> wrote:
> Seems like it might be possible to simplify/consolidate the VM-setting
> code that's now located at the end of lazy_scan_prune. Perhaps the two
> distinct blocks that call visibilitymap_set() could be combined into
> one.

FWIW I think that my error here might have had something to do with
hallucinating that the code already did things that way.

At the time this went in, I was working on a patchset that did things
this way (more or less). It broke the dependency on
all_visible_according_to_vm entirely, which simplified the
set-and-check-VM code that's now at the end of lazy_scan_prune.

Not sure how practical it'd be to do something like that now (not
offhand), but something to consider.

-- 
Peter Geoghegan

Commits

  1. Fix explicit valgrind interaction in read_stream.c.

  2. Reduce scope of heap vacuum per_buffer_data

  3. Use streaming read I/O in VACUUM's third phase

  4. Use streaming read I/O in VACUUM's first phase

  5. Convert heap_vac_scan_next_block() boolean parameters to flags

  6. Refactor tidstore.c iterator buffering.

  7. Increase default vacuum_buffer_usage_limit to 2MB.

  8. Remove unneeded vacuum_delay_point from heap_vac_scan_get_next_block

  9. Confine vacuum skip logic to lazy_scan_skip()

  10. Set all_visible_according_to_vm correctly with DISABLE_PAGE_SKIPPING

  11. Tighten up VACUUM's approach to setting VM bits.