pgstattuple The pgstattuple module provides various functions to obtain tuple-level statistics. pgstattuple(text) returns record pgstattuple returns a relation's physical length, percentage of dead tuples, and other info. This may help users to determine whether vacuum is necessary or not. The argument is the target relation's name (optionally schema-qualified). For example: 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 The output columns are: Column Type Description table_len bigint Physical relation length in bytes tuple_count bigint Number of live tuples tuple_len bigint Total length of live tuples in bytes tuple_percent float8 Percentage of live tuples dead_tuple_count bigint Number of dead tuples dead_tuple_len bigint Total length of dead tuples in bytes dead_tuple_percent float8 Percentage of dead tuples free_space bigint Total free space in bytes free_percent float8 Percentage of free space pgstattuple acquires only a read lock on the relation. So the results do not reflect an instantaneous snapshot; concurrent updates will affect them. pgstattuple judges a tuple is dead if HeapTupleSatisfiesNow returns false. pgstattuple(oid) returns record This is the same as pgstattuple(text), except that the target relation is specified by OID. pgstatindex(text) returns record pgstatindex returns a record showing information about a btree index. For example: 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 The output columns are: Column Type Description version integer Btree version number tree_level integer Tree level of the root page index_size bigint Total number of pages in index root_block_no bigint Location of root block internal_pages bigint Number of internal (upper-level) pages leaf_pages bigint Number of leaf pages empty_pages bigint Number of empty pages deleted_pages bigint Number of deleted pages avg_leaf_density float8 Average density of leaf pages leaf_fragmentation float8 Leaf page fragmentation As with pgstattuple, the results are accumulated page-by-page, and should not be expected to represent an instantaneous snapshot of the whole index. pg_relpages(text) returns bigint pg_relpages returns the number of pages in the relation. Tatsuo Ishii and Satoshi Nagayasu