Re: Postgresql and resource isolation

On Thu, Nov 15, 2007 at 10:12:51AM -0800, Garber, Mikhail wrote:
>
> A) "resource governor" - the ability to configure how much resources (IO
> per second, CPU slices) particular users or sessions are allowed to use

PostgreSQL is not like several other commercial systems, in that it doesn't
"take over" the OS as some others do. So it sort of can't do some of these
things.

Moreover, there is a possible problem with putting in these governors, which
is called priority inversion. Because Postgres has quite advanced
concurrency control, it is possible for a user who has been "throttled" to
restrict the ability of others to do their work, too. A paper discussed not
long ago in one of the mailing lists, however, suggests this problem isn't
as bad as some (including me) historically thought. I can't put my fingers
on it this minute, but a little digging in the archives for "nice settings"
or something similar ought to turn it up.

> And more general question - what are the plans to support these and
> similar features in Postgresql?

If someone comes along with an implementation that doesn't impose serious
costs on the rest of the system, I'd be surprised if people balked. But I
know of nobody working on it today.

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Andrew Sullivan
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