Re: DB on a ramdisk (was Re: Temporary, In-memory Postgres DB?)

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: DB on a ramdisk (was Re: Temporary, In-memory Postgres DB?)
Date: 2007-11-07 17:04:36
Message-ID: 18289.1194455076@sss.pgh.pa.us
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Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> writes:
> On 11/07/07 09:58, Tom Lane wrote:
>> Or put it on a ramdisk filesystem.

> But doesn't that just add more overhead and reduce the amount of
> memory that the OS can cache things in?

It's very possibly not a win, but the kinds of people who ask this
question at all do not understand the concept of caching, so I'm
sure they'll be happier with a solution where the data demonstrably
never hits disk ;-)

A case where it could be a win is where you are thrashing the DB with
heavy update load. Even if everything is cached there will be a pretty
serious amount of disk write traffic, which'd possibly interfere with
other system activity.

regards, tom lane

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