Re: patch for new feature: Buffer Cache Hibernation

2011/6/1 Tatsuo Ishii <ishii(at)postgresql(dot)org>:
>> Yeah, I'm pretty well convinced this whole approach is a dead end.
>> Priming the OS buffer cache seems way more useful.  I also think
>> saving the blocks to be read rather than the actual blocks makes a lot
>> more sense.
>
> Well, his proposal works on any platforms PostgreSQL supports. On the
> other hand PgFincore works on Linux only. Who wants Linux only tool be
> in core?

I don't want to compete the features here. Just for the completeness:
PgFincore 'snapshot' is possible on any platform supporting mincure()
(most support it, for widows alternatives exists). For restoring, it
can be a ReadBuffer for postgresql cache; for OS it can be an
open(),read(X), read (Y), close() *or* posix_fadvise() which can be
less destructive (I did only via posix_fadv but nothing prevent to
change that when posix support is not present).
And we already have linux-only feature in-core, fortunately because it
is usefull feature and I really like to add more posix_fadvise call
(*this* will really help read and cache strategy more than any hack we
can do to try to workaround kernel decisions)
Note that BSD developers can change that and make posix_fadvise work:
it has been sitting in their TODO list since some years now.

Anyway we need this patch on-list to go ahead.

>
> Also I really want to see the performance comparison between these two
> approaches in the real world database.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp
>
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Cédric Villemain               2ndQuadrant
http://2ndQuadrant.fr/     PostgreSQL : Expertise, Formation et Support