Learning PostgreSQL 11 - Third Edition

Getting the database and database object size

Managing disk space and assigning table spaces to tables as well as databases requires knowledge of the size of the database and database objects. When performing a logical restore of a certain table, you could get information about the progress by comparing the original database table size to the one that is being restored. Finally, the database object size often gives information about bloats.

Bloats are wasted disk space due to concurrent data manipulation. Heavily updated systems often get bloated due to the nature of MVCC. Bloats are often cleaned up by vacuum, so disabling the auto vacuum is not recommended.

To get the database size, you can get the oid database from the pg_database table ...