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From: Tomas Vondra <tv@fuzzy.cz>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Stefan Keller <sfkeller@gmail.com>
Cc: Wales Wang <wormwang@yahoo.com>
Cc: Jeff Janes <jeff.janes@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Cc: Stephen Frost <sfrost@snowman.net>
Subject:  Re: [PERFORM] Re: [PERFORM] Re: 回复： [PERFORM] PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?
Date: Tue, 28 Feb 2012 14:38:57 +0100
Message-ID: <8da9b15646d973a5ee23ba49faeee8fd.squirrel@sq.gransy.com> (raw)
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On 28 Únor 2012, 14:08, Claudio Freire wrote:
> On Tue, Feb 28, 2012 at 5:30 AM, Stefan Keller <sfkeller@gmail.com> wrote:
>>
>> But what I'm finally after is a solution, where records don't get
>> pushed back to disk a.s.a.p. but rather got hold in memory as long as
>> possible assuming that there is enough memory.
>
> fsync = off ?

I don't think this is a viable idea, unless you don't care about the data.

Moreover, "fsyn=off" does not mean "not writing" and writing does not mean
"removing from shared buffers". A page written/fsynced during a checkpoint
may stay in shared buffers.

AFAIK the pages are not removed from shared buffers without a reason. So a
dirty buffer is written to a disk (because it needs to, to keep ACID) but
stays in shared buffers as "clean" (unless it was written by a backend,
which means there's not enough memory).

Tomas




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  Subject: Re:  Re: [PERFORM] Re: [PERFORM] Re: 回复： [PERFORM] PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?
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