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? - Mailing list pgsql-performance

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