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(at)sss(dot)pgh(dot)pa(dot)us]
> Отправлено: 16 ieoya?y 2000 a. 8:50
> Кому: Bruce Momjian
> Копия: pgsql-hackers(at)postgreSQL(dot)org
> Тема: Re: [HACKERS] Possible performance improvement: buffer
> replacement policy
>
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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