Re: multiple databases vs multiple clusters on the same host

On 28 Září 2013, 20:12, Eugene Ostrovsky wrote:
> Hello!
>
> I would like to find out what is the difference in hardware resources
> consuming between two solutions:
> 1. Several databases in the same postgresql cluster
> 2. Several clusters (one per each database) on the same host
>
> Currently I have about 10 databases in the same cluster. For some reasons
> I'm going to switch to using separate clusters on the same machine. I
> suspect that this could affect the performance.
>
> Any ideas on how much more hardware resources will be consumed?

Well, that's hard to say because we don't know (a) the version of
PostgreSQL you're using, (2) how you use it and (c) what hardware you use.

There are probably some corner cases where this might improve the
performance, but in most cases it's going to be worse. Why are you
switching to multiple clusters?

For example consider that you'll probably have to use much smaller shared
buffers (which might cause issues on the active database, while the other
databases don't use their portion of memory), you'll have to either use
much smaller max_connections or decrease work_mem (you can't just keep the
values because then you might run into OOM much more frequently) etc.

Tomas