Replaying backups

Having a backup is pointless unless you have tried to actually replay it. Fortunately, this is easy to do. If you have created a plaintext backup, simply take the SQL file and execute it. The following example shows how that can be done:

psql your_db < your_file.sql

A plaintext backup is simply a text file containing everything. We can always simply replay a text file.

If you have decided on a custom format or directory format, you can use pg_restore to replay the backup. Additionally, pg_restore allows you to do all kinds of fancy things, such as replaying just part of a database. In most cases, however, you will simply replay the entire database. In this example, we will create an empty database and just replay a custom format dump:

[hs@linuxpc backup]$ createdb new_db
[hs@linuxpc backup]$ pg_restore -d new_db -j 4 /tmp/dump.fc

Note that pg_restore will add data to an existing database. If your database is not empty, pg_restore might error out...