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Diffstat (limited to 'contrib/pgstattuple/README.pgstattuple')
-rw-r--r-- | contrib/pgstattuple/README.pgstattuple | 62 |
1 files changed, 37 insertions, 25 deletions
diff --git a/contrib/pgstattuple/README.pgstattuple b/contrib/pgstattuple/README.pgstattuple index 7237b9a4dc8..804c37c6a91 100644 --- a/contrib/pgstattuple/README.pgstattuple +++ b/contrib/pgstattuple/README.pgstattuple @@ -1,27 +1,36 @@ -pgstattuple README 2001/10/01 Tatsuo Ishii +pgstattuple README 2002/08/22 Tatsuo Ishii 1. What is pgstattuple? - pgstattuple returns the percentage of the "dead" tuples of a - table. This will help users to judge if vacuum is needed. - - In addition, pgstattuple prints more detailed information using - NOTICE. - -test=# select pgstattuple('tellers'); -NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 320 (0.01MB, 18.75%) free/reusable space: 0.01MB (18.06%) overhead: 62.02% - pgstattuple -------------- - 18.75 -(1 row) - - Above example shows tellers table includes 18.75% dead tuples. - - physical length physical size of the table in MB - live tuples information on the live tuples - dead tuples information on the dead tuples - free/reusable space available space - overhead overhead space + pgstattuple returns the table length, percentage of the "dead" + tuples of a table 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_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: + +table_len -- physical table 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 % 2. Installing pgstattuple @@ -31,12 +40,15 @@ NOTICE: physical length: 0.08MB live tuples: 20 (0.00MB, 1.17%) dead tuples: 32 3. Using pgstattuple - pgstattuple can be called as a function: + pgstattuple may be called as a SRF (set returning function) and is + defined as follows: - pgstattuple(TEXT) RETURNS FLOAT8 + CREATE OR REPLACE FUNCTION pgstattuple(text) RETURNS SETOF pgstattuple_view + AS 'MODULE_PATHNAME', 'pgstattuple' + LANGUAGE 'c' WITH (isstrict); - The argument is the table name. pgstattuple returns the percentage - of the "dead" tuples of a table. + The argument is the table name. Note that pgstattuple never + returns more than 1 tuple. 4. Notes |