disk usage Each table has a primary heap disk file where most of the data is stored. To store long column values, there is also a TOAST file associated with the table, named based on the table's OID (actually pg_class.relfilenode), and an index on the TOAST table. There also may be indexes associated with the base table. You can monitor disk space from three places: from psql using VACUUM information, from psql using contrib/dbsize, and from the command line using contrib/oid2name. Using psql on a recently vacuumed (or analyzed) database, you can issue queries to see the disk usage of any table: play=# SELECT relfilenode, relpages play-# FROM pg_class play-# WHERE relname = 'customer'; relfilenode | relpages -------------+---------- 16806 | 60 (1 row) Each page is typically 8 kilobytes. (Remember, relpages is only updated by VACUUM and ANALYZE.) To show the space used by TOAST tables, use a query based on the heap relfilenode shown above: play=# SELECT relname, relpages play-# FROM pg_class play-# WHERE relname = 'pg_toast_16806' OR play-# relname = 'pg_toast_16806_index' play-# ORDER BY relname; relname | relpages ----------------------+---------- pg_toast_16806 | 0 pg_toast_16806_index | 1 You can easily display index usage too: play=# SELECT c2.relname, c2.relpages play-# FROM pg_class c, pg_class c2, pg_index i play-# WHERE c.relname = 'customer' AND play-# c.oid = i.indrelid AND play-# c2.oid = i.indexrelid play-# ORDER BY c2.relname; relname | relpages ----------------------+---------- customer_id_indexdex | 26 It is easy to find your largest files using psql: play=# SELECT relname, relpages play-# FROM pg_class play-# ORDER BY relpages DESC; relname | relpages ----------------------+---------- bigtable | 3290 customer | 3144 dbsize loads functions into your database that allow you to find the size of a table or database from inside psql without the need for VACUUM/ANALYZE. You can also use oid2name to show disk usage. See README.oid2name for examples. It includes a script shows disk usage for each database.