Horton

Re: Confine vacuum skip logic to lazy_scan_skip

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Melanie Plageman <melanieplageman@gmail.com>
Cc: Thomas Munro <thomas.munro@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Tomas Vondra <tomas@vondra.me>, Noah Misch <noah@leadboat.com>, vignesh C <vignesh21@gmail.com>, Andres Freund <andres@anarazel.de>, Pg Hackers <pgsql-hackers@postgresql.org>, Heikki Linnakangas <hlinnaka@iki.fi>, Nazir Bilal Yavuz <byavuz81@gmail.com>, Robert Haas <robertmhaas@gmail.com>, "Andrey M. Borodin" <x4mmm@yandex-team.ru>
Date: 2025-02-18T15:52:04Z
Lists: pgsql-hackers 
Melanie Plageman <melanieplageman@gmail.com> writes:
> On Sun, Feb 16, 2025 at 1:12 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Basically, Coverity doesn't understand that a successful call to
>> read_stream_next_buffer must set per_buffer_data here.  I don't
>> think there's much chance of teaching it that, so we'll just
>> have to dismiss this item as "intentional, not a bug".

> Is this easy to do? Like is there a list of things from coverity to ignore?

Their website has a table of live issues, and we can just mark this
one "dismissed".  I'm not entirely sure how they recognize dismissed
issues --- it's not perfect, because old complaints tend to get
resurrected after changes in nearby code.  But it's good enough.

>> I do have a suggestion: I think the "per_buffer_data" variable
>> should be declared inside the "while (true)" loop not outside.

> Done and pushed. Thanks!

Thanks, looks better now.

			regards, tom lane

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.