Re: Extension Enhancement: Buffer Invalidation in pg_buffercache

On Tue, Apr 30, 2024 at 7:17 AM Thomas Munro <thomas.munro@gmail.com> wrote:

On Tue, Apr 30, 2024 at 6:47 AM Maksim Milyutin <milyutinma@gmail.com> wrote:

Should not we call at the end the StrategyFreeBuffer() function to add target buffer to freelist and not miss it after invalidation?

Please take a look at this issue, current implementation of EvictUnpinnedBuffer() IMO is erroneous - evicted buffers are lost permanently and will not be reused again

I don't think that's true: it is not lost permanently, it'll be found
by the regular clock hand.  Perhaps it should be put on the freelist
so it can be found again quickly, but I'm not sure that's a bug, is
it?

Yeah, you are right. Thanks for clarification.

CLOCK algorithm will reuse it eventually but being of evicted cleared buffer in freelist might greatly restrict the time of buffer allocation when all others buffers were in use.

-- 
Best regards,
Maksim Milyutin