Re: [pgsql-general] In memory tables/databases

From: "Alexander Todorov" <alexx(dot)todorov(at)gmail(dot)com>
To: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: [pgsql-general] In memory tables/databases
Date: 2007-07-01 18:29:07
Message-ID: 6e97ff300707011129k52a67d0fy1d7b72daa3503ed@mail.gmail.com
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On 7/1/07, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> As long as shared_buffers is high enough, there doesn't seem to be much
> point in worrying about this; the incremental performance gain will be
> minimal since everything will be in RAM anyway.

Yes it will be but this does not mean there will be no disk i/o
operations. Database contents still have to be backed up on disk
(unless there is a mechanism of delayed wrtite to disk which I am not
aware of). The memory engine as designed by MySQL (my interpretation)
is to avoid the disk operations.

> Or do you think losing
> the content of the database at server crash is a feature?

Yes it is. Anything designed to live in memory should be used to hold
non vital information. The loosing/recreation of this information is
implied by design of the application.
One example is bittorent trackers which maintain data about the
connected peers. Since connections are created/destroyed and there are
more selects than insert/updates these applications use memory tables.

Greetings,
Alexander.

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