This module contains several functions that report the size of a given
database object:
int8 database_size(name)
int8 relation_size(text)
int8 pg_database_size(oid)
int8 pg_tablespace_size(oid)
int8 pg_relation_size(oid)
text pg_size_pretty(int8)
The first two functions:
SELECT database_size('template1');
SELECT relation_size('pg_class');
take the name of the object, and support databases and tables. Please
note that relation_size() only reports table file usage and not the
space used by indexes and toast tables.
Functions using oids are:
SELECT pg_database_size(1); -- template1 database
SELECT pg_tablespace_size(1663); -- pg_default tablespace
SELECT pg_relation_size(1259); -- pg_class table size
pg_relation_size() will report the size of the table, index and toast
table OIDs, but they must be requested individually. To obtain the total
size of a table including all helper files you'd have to do something
like:
XXX This query does not work, syntax error XXX
SELECT pg_relation_size(cl.oid) AS tablesize,
CASE WHEN reltoastrelid=0 THEN 0
ELSE pg_relation_size(reltoastrelid) END AS toastsize,
SUM(pg_relation_size(indexrelid)) AS indexsize,
pg_size_pretty(pg_relation_size(cl.oid)
+ pg_relation_size(reltoastrelid)
+ SUM(pg_relation_size(indexrelid))::int8)
AS totalsize
FROM pg_class cl
JOIN pg_index ON cl.oid=indrelid
WHERE relname = 'pg_rewrite'
GROUP BY 1,2
This sample query utilizes the helper function pg_size_pretty(int8),
which formats the number of bytes into a convenient string using KB, MB,
GB. It is also contained in this module.
To install, just run make; make install. Finally, load the functions
into any database using dbsize.sql.
