Re: multiple databases vs multiple clusters on the same host

Thanks for the answer!

About you questions:
1. Postgres 9.3
2. There are about 30-50 user connections. Actually Only 2 of databases are used intensively, others only in rare cases.
3. Hardware is AMD Phenom II X4 965, 8 Gb RAM, 2 SATA2 HDD in software mirror raid
4. The reason to switch to multiple clusters is that my software uses roles (login users and groups) for a single database. There are some problems with it in case of several databases because in postgres roles are shared between all the databases in the same cluster.

28.09.2013, 22:29, "Tomas Vondra" <tv(at)fuzzy(dot)cz>:
> 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