pgstattuple

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) or OID. 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 described in Table F-23 .

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 HeapTupleSatisfiesDirty returns false.

This is the same as pgstattuple(regclass) , except that the target relation is specified as TEXT. This function is kept because of backward-compatibility so far, and will be deprecated in some future release.

pgstatindex returns a record showing information about a B-tree index. For example:

test=> SELECT * FROM pgstatindex('pg_cast_oid_index');
-[ RECORD 1 ]------+------
version            | 2
tree_level         | 0
index_size         | 16384
root_block_no      | 1
internal_pages     | 0
leaf_pages         | 1
empty_pages        | 0
deleted_pages      | 0
avg_leaf_density   | 54.27
leaf_fragmentation | 0

The output columns are:

The reported index_size will normally correspond to one more page than is accounted for by internal_pages + leaf_pages + empty_pages + deleted_pages , because it also includes the index's metapage.

As with pgstattuple , the results are accumulated page-by-page, and should not be expected to represent an instantaneous snapshot of the whole index.

This is the same as pgstatindex(regclass) , except that the target index is specified as TEXT. This function is kept because of backward-compatibility so far, and will be deprecated in some future release.

pgstatginindex returns a record showing information about a GIN index. For example:

test=> SELECT * FROM pgstatginindex('test_gin_index');
-[ RECORD 1 ]--+--
version        | 1
pending_pages  | 0
pending_tuples | 0

The output columns are:

pg_relpages returns the number of pages in the relation.

This is the same as pg_relpages(regclass) , except that the target relation is specified as TEXT. This function is kept because of backward-compatibility so far, and will be deprecated in some future release.