Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode - Mailing list pgsql-hackers

From David Rowley
Subject Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode
Date
Msg-id CAApHDvo57+sYWx+nwM3DXM2m0S8f1XDruTURSWjdwOSRKu6s9Q@mail.gmail.com
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In response to Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode  (Melanie Plageman <melanieplageman@gmail.com>)
Responses Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode
Re: Option to not use ringbuffer in VACUUM, using it in failsafe mode
List pgsql-hackers
On Thu, 6 Apr 2023 at 12:42, Melanie Plageman <melanieplageman@gmail.com> wrote:
> Attached is a v12 of the whole vacuum_buffer_usage_limit patch set which
> includes a commit to fix the bug in master and a commit to move relevant
> code from vacuum() up into ExecVacuum().

I'm still playing catch up to the moving of the pre-checks from
vacuum() to ExecVacuum().  I'm now wondering...

Is it intended that VACUUM t1,t2; now share the same strategy?
Currently, in master, we'll allocate a new strategy for t2 after
vacuuming t1. Does this not mean we'll now leave fewer t1 pages in
shared_buffers because the reuse of the strategy will force them out
with t2 pages?  I understand there's nothing particularly invalid
about that, but it is a change in behaviour that the patch seems to be
making with very little consideration as to if it's better or worse.

David



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