What is PGDATA in PostgreSQL

Question

New to PostgreSQL, experienced in Oracle. Trying to understand what PGDATA is.

Reading about it, it seems to contain what is necessary to create the initial Database cluster.

I did and install and I am converting some data from Oracle. The path the installation put PGDATA by default is in a file system that is fairly small. So I am looking to move it into a bigger file system.

So my questions are:

1. Is this akin to the Oracle Data Dictionary?
2. Do I need to put all my application data in that path or is it best practice not to?
3. I know I can just take the default and create a new database in the bigger file system, but should I?

Thanks

Answer 1

One major difference between oracle and postgres is documentation quality. If you plan to work with postgres - make some time (a day ot two) to read it.

You can find full description for postgres files here: http://www.postgresql.org/docs/current/static/storage-file-layout.html

Generally you do not need to move your whole DB if you do not want. You can create a tablespace outside postgres data directory (via linux symlink).

Still you may want to move your whole DB to a bigger (faster?) FS. PGDATA directory contains Write Ahead Log (similar to Oracle REDO log). Slow operations on WAL mean slow DB in general. The size of the WAL files depends on DB setting and activity - you may want to be sure there is enough free space for it.