Ответ: [HACKERS] Possible performance improvement: buffer replacement policy

Excuse me but what is LRU-2?
I know that in Oracle unused buffers are not in
simple LRU list: Oracle tries to postpone writes
as long as possible -:)

Vadim

> ----- Исходное сообщение -----
> От:        Tom Lane [SMTP:tgl@sss.pgh.pa.us]
> Отправлено:        16 ieoya?y 2000 a. 8:50
> Кому:        Bruce Momjian
> Копия:        pgsql-hackers@postgreSQL.org
> Тема:        Re: [HACKERS] Possible performance improvement: buffer
> replacement policy
>
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> It looks like it wouldn't take too much work to replace shared buffers
> >> on the basis of LRU-2 instead of LRU, so I'm thinking about trying it.
> >>
> >> Has anyone looked into this area?  Is there a better method to try?
>
> > Sounds like a perfect idea.  Good luck.  :-)
>
> Actually, the idea went down in flames :-(, but I neglected to report
> back to pghackers about it.  I did do some code to manage buffers as
> LRU-2.  I didn't have any good performance test cases to try it with,
> but Richard Brosnahan was kind enough to re-run the TPC tests previously
> published by Great Bridge with that code in place.  Wasn't any faster,
> in fact possibly a little slower, likely due to the extra CPU time spent
> on buffer freelist management.  It's possible that other scenarios might
> show a better result, but right now I feel pretty discouraged about the
> LRU-2 idea and am not pursuing it.
>
>             regards, tom lane