Обсуждение: pg_dump and database size question

Hi,


I have postgres 9.0.2  server with a 2.4GB database.
After pg_dump of the database, the size increased with aprox 200MB ... why?
I make some tests and the total_relation_size is increased, but the
relation_size not.

thanks

Birta Levente

Birta,

> After pg_dump of the database, the size increased with aprox 200MB ...

How are you dumping the database?  Are you using -Fc on the command line, or
are you dumping to a text file?  I have nothing to quantify my comment, but
it seems possible that with a database of that size, the additional overhead
is related to it being a text-based dump file.

-- Gary Chambers

On Thursday 06 January 2011 5:58:13 am Birta Levente wrote:
> Hi,
>
>
> I have postgres 9.0.2  server with a 2.4GB database.
> After pg_dump of the database, the size increased with aprox 200MB ... why?
> I make some tests and the total_relation_size is increased, but the
> relation_size not.
>
> thanks
>
> Birta Levente

Are you saying the existing database increases in size after the dump or that
when you dump/restore the restored db is greater in size than what it was
previously?  Also if it was a dump/restore where you changing Postgres
versions? In any case total_relation_size includes more information than
relation_size; notably TOAST space, indexes, and two more of the data
forks(main,fsm,vm). So the difference is in one of those. See here for more
info:
http://www.postgresql.org/docs/9.0/interactive/functions-admin.html

As to why, that probably depends on the answer to my previous questions.

--
Adrian Klaver
adrian.klaver@gmail.com