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

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.