Re: Mapping a database completly into Memory

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Mapping a database completly into Memory
Date: 2003-07-28 16:58:19
Message-ID: 15250.1059411499@sss.pgh.pa.us
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Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> If we had a portable way
>> of preventing the kernel from caching the same page, it would make more
>> sense to run with large shared_buffers.

> Really? I thought we wanted to move the other way ... that is, if we could
> get over the portability issues, eliminate shared_buffers entirely and rely
> completely on the OS cache.

That seems unlikely to happen: there are cache-coherency problems if you
don't do your page-level access through shared buffers. Some have
suggested using mmap access to the data files in place of shared memory,
but that introduces a slew of issues of its own. It might happen but
I'm not holding my breath.

regards, tom lane

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