-This module contains two functions that report the size of a given
-database or relation. E.g.,
+This module contains several functions that report the size of a given
+database object:
-SELECT database_size('template1');
-SELECT relation_size('pg_class');
+ int8 database_size(name)
+ int8 relation_size(text)
-These functions report the actual file system space. Thus, users can
-avoid digging through the details of the database directories.
+ int8 pg_database_size(oid)
+ int8 pg_tablespace_size(oid)
+ int8 pg_relation_size(oid)
-Copy this directory to contrib/dbsize in your PostgreSQL source tree.
-Then just run make; make install. Finally, load the functions into any
-database using dbsize.sql.
+ 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.
-When computing the size of a table, it does not include TOAST or index
-disk space.