pg_stats
This is an extension of PostgreSQL, which contains some customized statistics views.
Installation
Execute make install on the contrib directory, or Put two files, pg_stats.control and pg_stats--1.0.sql, on the ~/share/postgresql/extension/ subdirectory.
Then, execute CREATE EXTENSION pg_stats on all databases you want to use this extension.
TABLES
The view pg_stat_tables is created by joining with pg_stat_user_tables and pg_statio_user_tables, and is added some columns.
Additional columns
| column | description |
|---|---|
| idx_scan_ratio | Ratio [%] of number of index scans to number of total scans, i.e., 100 * idx_scan/(seq_scan + idx_scan) |
| hit_ratio | Ratio [%] of number of buffer hits to total number of read blocks, i.e., 100 * heap_blks_hit/(heap_blks_read + heap_blks_hit) |
| ins_ratio | Ratio [%] of number of INSERT operations to number of total operations, i.e., 100 * n_tup_ins/(n_tup_ins + n_tup_upd + n_tup_del) |
| upd_ratio | Ratio [%] of number of UPDATE operations to number of total operations, i.e., 100 * n_tup_upd/(n_tup_ins + n_tup_upd + n_tup_del) |
| del_ratio | Ratio [%] of number of DELETE operations to number of total operations, i.e., 100 * n_tup_del/(n_tup_ins + n_tup_upd + n_tup_del) |
| hot_upd_ratio | Ratio [%] of number of rows HOT updated to number of rows updated, i.e., 100 * n_tup_hot_upd / n_tup_upd |
| table_size | Disk space used by the specified fork ('main', 'fsm', 'vm') of the specified table |
| total_size | Total disk space used by the specified table, including all indexes and TOAST data |
Example
# SELECT * FROM pg_stat_tables;
-[ RECORD 1 ]-----+------------------------------
schemaname | public
relname | pgbench_accounts
relid | 16391
seq_scan | 1
idx_scan | 194492
idx_scan_ratio | 99
seq_tup_read | 100000
idx_tup_fetch | 194492
heap_blks_read | 2011
heap_blks_hit | 391145
hit_ratio | 99.00
n_tup_ins | 100000
n_tup_upd | 97246
n_tup_del | 0
ins_ratio | 50.70
upd_ratio | 49.30
del_ratio | 0.00
n_tup_hot_upd | 75326
hot_upd_ratio | 77.46
table_size | 16 MB
total_size | 20 MB
last_vacuum | 2016-09-25 07:33:06.279177+00
last_autovacuum | 2016-09-26 03:48:55.294943+00
vacuum_count | 1
autovacuum_count | 1
last_analyze | 2016-09-25 07:33:06.32018+00
last_autoanalyze | 2016-09-26 03:48:01.615811+00
analyze_count | 1
autoanalyze_count | 7
-[ RECORD 2 ]-----+------------------------------
schemaname | public
relname | pgbench_branches
relid | 16394
seq_scan | 136287
idx_scan | 18853
--- continue ---
INDEXES
The view pg_stat_indexes is created by joining with pg_stat_user_indexes and pg_statio_user_indexes, and is added some columns.
Additional columns
| column | description |
|---|---|
| idx_hit_ratio | Ratio [%] of number of buffer hits to number of all index read, i.e., 100 * idx_blks_hit/(idx_blks_read + idx_blks_hit) |
| index_size | Disk space used by the specified fork ('main', 'fsm') of the specified index |
Example
# SELECT * FROM pg_stat_indexes;
-[ RECORD 1 ]-+----------------------
schemaname | public
relname | pgbench_accounts
indexrelname | pgbench_accounts_pkey
relid | 16391
idx_scan | 194492
idx_tup_read | 221404
idx_tup_fetch | 194492
idx_blks_read | 551
idx_blks_hit | 465398
idx_hit_ratio | 99
index_size | 4408 kB
-[ RECORD 2 ]-+----------------------
schemaname | public
relname | pgbench_branches
indexrelname | pgbench_branches_pkey
relid | 16394
idx_scan | 18853
idx_tup_read | 946621
idx_tup_fetch | 18853
idx_blks_read | 2
idx_blks_hit | 19416
idx_hit_ratio | 99
index_size | 16 kB
-[ RECORD 3 ]-+----------------------
schemaname | public
relname | pgbench_tellers
indexrelname | pgbench_tellers_pkey
relid | 16388
idx_scan | 19775
idx_tup_read | 533645
idx_tup_fetch | 17428
idx_blks_read | 5
idx_blks_hit | 27006
idx_hit_ratio | 99
index_size | 40 kB
USERS
The view pg_stat_users shows login time of each user.
| column | description |
|---|---|
| dattname | Name of the database this backend is connected to |
| usename | Name of the user logged into this backend |
| pid | Process ID of this backend |
| backend_start | Time when this process was started, i.e., when the client connected to the server |
| login_time | How long this backend is running |
Example
# SELECT * FROM pg_stat_users;
datname | usename | pid | backend_start | login_time
----------+---------+------+-------------------------------+--------------
sampledb | vagrant | 4972 | 2016-09-26 03:32:06.782921+00 | 00:05:09.257
sampledb | vagrant | 4988 | 2016-09-26 03:35:34.716738+00 | 00:01:41.324
sampledb | vagrant | 4998 | 2016-09-26 03:37:11.236835+00 | 00:00:04.804
sampledb | vagrant | 4999 | 2016-09-26 03:37:11.239046+00 | 00:00:04.801
sampledb | vagrant | 5000 | 2016-09-26 03:37:11.240234+00 | 00:00:04.8
sampledb | vagrant | 5001 | 2016-09-26 03:37:11.241369+00 | 00:00:04.799
(6 rows)
QUERIES
The view pg_stat_queries shows queries and their durations.
| column | description |
|---|---|
| dattname | Name of the database this backend is connected to |
| usename | Name of the user logged into this backend |
| pid | Process ID of this backend |
| duration | How long this query is running |
| waiting | True if this backend is currently waiting on a lock |
| query | Text of this backend's most recent query |
Example
# SELECT * FROM pg_stat_queries;
datname | usename | pid | duration | waiting | query
----------+---------+------+--------------+---------+----------------------------------------------------------------------------
sampledb | vagrant | 4988 | 00:01:42.832 | f | BEGIN;
sampledb | vagrant | 4998 | 00:00:00.004 | t | UPDATE pgbench_branches SET bbalance = bbalance + -4057 WHERE bid = 1;
sampledb | vagrant | 4999 | 00:00:00.004 | f | END;
sampledb | vagrant | 5000 | 00:00:00.001 | f | UPDATE pgbench_accounts SET abalance = abalance + -1378 WHERE aid = 62207;
sampledb | vagrant | 5001 | 00:00:00.002 | t | UPDATE pgbench_branches SET bbalance = bbalance + 550 WHERE bid = 1;
(5 rows)
LONG TRANSACTIONS
The view pg_stat_long_trx catches long transactions.
| column | description |
|---|---|
| pid | Process ID of this backend. |
| waiting | True if this backend is currently waiting on a lock. |
| duration | How long this transaction is running. |
| query | Text of this backend's most recent query. |
Example
# SELECT * FROM pg_stat_long_trx;
pid | waiting | duration | query
------+---------+--------------+------------------------------------------------------------------------
4988 | t | 00:00:34.031 | UPDATE test SET id = 10;
5026 | f | 00:05:43.063 | LOCK test;
5054 | t | 00:00:00.003 | UPDATE pgbench_branches SET bbalance = bbalance + -3093 WHERE bid = 1;
5055 | f | 00:00:00.002 | UPDATE pgbench_tellers SET tbalance = tbalance + -1561 WHERE tid = 1;
5056 | f | 00:00:00.001 | SELECT abalance FROM pgbench_accounts WHERE aid = 42689;
5057 | f | 00:00:00.007 | END;
(6 rows)
WAITING LOCKS
The view pg_stat_waiting_locks shows waiting locks.
| column | description |
|---|---|
| locktype | Type of the lockable object |
| relname | Name of the table, index, view, etc. |
| pid | Process ID of this backend |
| mode | Name of the lock mode held or desired by this process |
| query | Text of this backend's most recent query |
| duration | How long this lock is waiting |
Example
# SELECT * FROM pg_stat_waiting_locks;
locktype | relname | pid | mode | query | duration
---------------+---------+------+------------------+--------+--------------
relation | test | 4988 | RowExclusiveLock | UPDATE | 00:01:02.087
transactionid | | 5061 | ShareLock | UPDATE | 00:00:00.001
transactionid | | 5063 | ShareLock | UPDATE | 00:00:00.006
transactionid | | 5064 | ShareLock | UPDATE | 00:00:00.01
(4 rows)