pgstattuple pgstattuple modules provides various functions to obtain tuple statistics. pgstattuple() returns the relation length, percentage of the "dead" tuples of a relation and other info. This may help users to determine whether vacuum is necessary or not. Here is an example session: test=> \x Expanded display is on. test=> SELECT * FROM pgstattuple('pg_catalog.pg_proc'); -[ RECORD 1 ]------+------- table_len | 458752 tuple_count | 1470 tuple_len | 438896 tuple_percent | 95.67 dead_tuple_count | 11 dead_tuple_len | 3157 dead_tuple_percent | 0.69 free_space | 8932 free_percent | 1.95 Here are explanations for each column: Column Description table_len physical relation length in bytes tuple_count number of live tuples tuple_len total tuples length in bytes tuple_percent live tuples in % dead_tuple_len total dead tuples length in bytes dead_tuple_percent dead tuples in % free_space free space in bytes free_percent free space in % pgstattuple acquires only a read lock on the relation. So concurrent update may affect the result. pgstattuple judges a tuple is "dead" if HeapTupleSatisfiesNow() returns false. pg_relpages() returns the number of pages in the relation. pgstatindex() returns an array showing the information about an index: test=> \x Expanded display is on. test=> SELECT * FROM pgstatindex('pg_cast_oid_index'); -[ RECORD 1 ]------+------ version | 2 tree_level | 0 index_size | 8192 root_block_no | 1 internal_pages | 0 leaf_pages | 1 empty_pages | 0 deleted_pages | 0 avg_leaf_density | 50.27 leaf_fragmentation | 0 pgstattuple may be called as a relation function and is defined as follows: CREATE OR REPLACE FUNCTION pgstattuple(text) RETURNS pgstattuple_type AS 'MODULE_PATHNAME', 'pgstattuple' LANGUAGE C STRICT; CREATE OR REPLACE FUNCTION pgstattuple(oid) RETURNS pgstattuple_type AS 'MODULE_PATHNAME', 'pgstattuplebyid' LANGUAGE C STRICT; The argument is the relation name (optionally it may be qualified) or the OID of the relation. Note that pgstattuple only returns one row.