Thread: maximum number of databases and / or schemas in a single database instance

Menelaos PerdikeasSemantix <mperdikeas.semantix@gmail.com> writes:
> The following page:
> http://www.postgresql.org/about/

> mentions some limits but not the following:

> [1] maximum number of databases per database server instance
> [2] maximum number of schemas per database

> Is there empirical information on whether both these values can be as high
> as a few hundreds? (I don't really need any more for my use case)

You can certainly have hundreds of schemas.  I wouldn't really recommend
more than a few dozen databases per instance, though.  It tends to bog
down autovacuum, and remember you are storing a separate copy of the
system catalogs per database.  You might be able to make a few hundred
databases work all right if you don't mind expending some tuning effort;
but a few thousand is probably right out.

            regards, tom lane

On Sun, Aug 5, 2012 at 2:05 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Menelaos PerdikeasSemantix <mperdikeas.semantix@gmail.com> writes:
>> The following page:
>> http://www.postgresql.org/about/
>
>> mentions some limits but not the following:
>
>> [1] maximum number of databases per database server instance
>> [2] maximum number of schemas per database
>
>> Is there empirical information on whether both these values can be as high
>> as a few hundreds? (I don't really need any more for my use case)
>
> You can certainly have hundreds of schemas.

What about thousands of schemas? Is there significant cost to schemas
beyond the tables they contain?

Chris Angelico