19 KiB
19 KiB
User Guide
pg_stat_monitor extension contains a view called pg_stat_monitor, which contains all the monitoring information. Following is the list of columns in pg_stat_monitor.
| Column | Type | pg_stat_monitor | pg_stat_statments |
|---|---|---|---|
| bucket | integer | ✔️ | ❌ |
| bucket_start_time | timestamp with time zone | ✔️ | ❌ |
| userid | oid | ✔️ | ✔️ |
| dbid | oid | ✔️ | ✔️ |
| client_ip | inet | ✔️ | ❌ |
| queryid | text | ✔️ | ✔️ |
| query | text | ✔️ | ✔️ |
| application_name | text | ✔️ | ❌ |
| relations | text[] | ✔️ | ❌ |
| cmd_type | text[] | ✔️ | ❌ |
| elevel | integer | ✔️ | ❌ |
| sqlcode | integer | ✔️ | ❌ |
| message | text | ✔️ | ❌ |
| plans | bigint | ✔️ | ✔️ |
| plan_total_time | double precision | ✔️ | ✔️ |
| plan_min_timei | double precision | ✔️ | ✔️ |
| plan_max_time | double precision | ✔️ | ✔️ |
| plan_mean_time | double precision | ✔️ | ✔️ |
| plan_stddev_time | double precision | ✔️ | ✔️ |
| calls | bigint | ✔️ | ✔️ |
| total_time | double precision | ✔️ | ✔️ |
| min_time | double precision | ✔️ | ✔️ |
| max_time | double precision | ✔️ | ✔️ |
| mean_time | double precision | ✔️ | ✔️ |
| stddev_time | double precision | ✔️ | ✔️ |
| rows | bigint | ✔️ | ✔️ |
| shared_blks_hit | bigint | ✔️ | ✔️ |
| shared_blks_read | bigint | ✔️ | ✔️ |
| shared_blks_dirtied | bigint | ✔️ | ✔️ |
| shared_blks_written | bigint | ✔️ | ✔️ |
| local_blks_hit | bigint | ✔️ | ✔️ |
| local_blks_read | bigint | ✔️ | ✔️ |
| local_blks_dirtied | bigint | ✔️ | ✔️ |
| local_blks_written | bigint | ✔️ | ✔️ |
| temp_blks_read | bigint | ✔️ | ✔️ |
| temp_blks_written | bigint | ✔️ | ✔️ |
| blk_read_time | double precision | ✔️ | ✔️ |
| blk_write_time | double precision | ✔️ | ✔️ |
| resp_calls | text[] | ✔️ | ❌ |
| cpu_user_time | double precision | ✔️ | ❌ |
| cpu_sys_time | double precision | ✔️ | ❌ |
Here are some key features of pg_stat_monitor.
Buckets
pg_stat_monitor collects and aggregates data on a bucket basis. The size of a bucket and the number of buckets should be configured using GUC (Grand Unified Configuration). When a bucket time elapses, pg_stat_monitor resets all the statistics and switches to the next bucket. After the last bucket elapses, pg_stat_monitor goes back to the first bucket. All the data on the first bucket will vanish; therefore, users must read the buckets before that to not lose the data.
bucket: Accumulates the statistics per bucket. All the information and aggregate reset for each bucket. The bucket will be a number showing the number of buckets for which this record belongs.
bucket_start_time: shows the start time of the bucket.
postgres=# select bucket, bucket_start_time, query from pg_stat_monitor;
bucket | bucket_start_time | query
--------+-------------------------------+--------------------------------------------------------
2 | 2020-05-23 13:24:44.652415+00 | select * from pg_stat_monitor_reset()
3 | 2020-05-23 13:45:01.55658+00 | select bucket, bucket_start_time, query from pg_stat_monitor
2 | 2020-05-23 13:24:44.652415+00 | SELECT * FROM foo
(3 rows)
Query Information
userid: An ID of the user whom that query belongs. pg_stat_monitor is used to collect queries from all the users; therefore, userid is used to segregate the queries based on different users.
dbid: The database ID of the query. pg_stat_monitor accumulates queries from all the databases; therefore, this column is used to identify the database.
queryid: pg_stat_monitor generates a unique ID for each query (queryid).
query: The query column contains the actual text of the query. This parameter depends on the pg_stat_monitor.pgsm_normalized_query configuration parameters, in which format to show the query.
calls: Number of calls of that particular query.
Example 1: Shows the userid, dbid, unique queryid hash, query and total number of calls or that query.
postgres=# select userid, dbid, queryid, substr(query,0, 50) as query, calls from pg_stat_monitor;
userid | dbid | queryid | query | calls
--------+-------+------------------+---------------------------------------------------+-------
10 | 12709 | 214646CE6F9B1A85 | BEGIN | 1577
10 | 12709 | 8867FEEB8A5388AC | vacuum pgbench_branches | 1
10 | 12709 | F47D95C9DF863E43 | UPDATE pgbench_branches SET bbalance = bbalance + | 1577
10 | 12709 | 2FE0A6ABDC20623 | select substr(query,$1, $2) as query, cmd_type fr | 7
10 | 12709 | A83503D3E1F99139 | select userid, dbid, queryid, substr(query,$1, $ | 1
10 | 12709 | D4B1243AC3268B9B | select count(*) from pgbench_branches | 1
10 | 12709 | 2FE0A6ABDC20623 | select substr(query,$1, $2) as query, cmd_type fr | 1
10 | 12709 | 1D9BDBBCFB89F096 | UPDATE pgbench_accounts SET abalance = abalance + | 1577
10 | 12709 | 15343084284782B | update test SET a = $1 | 2
10 | 12709 | 939C2F56E1F6A174 | END | 1577
1 | 12709 | DAE6D269D27F2EC4 | SELECT FOR UPDATE test SET a = 1; | 1
10 | 12709 | 2B50C2406BFAC907 | INSERT INTO pgbench_history (tid, bid, aid, delta | 1577
10 | 12709 | F6DA9838660825CA | vacuum pgbench_tellers | 1
10 | 12709 | 3AFB8B2452721F9 | SELECT a from test for update | 1
10 | 12709 | A5CD0AF80D28363 | SELECT abalance FROM pgbench_accounts WHERE aid = | 1577
10 | 12709 | E445DD36B9189C53 | UPDATE pgbench_tellers SET tbalance = tbalance + | 1577
10 | 12709 | 4876BBA9A8FCFCF9 | truncate pgbench_history | 1
10 | 12709 | D3C2299FD9E7348C | select userid, dbid, queryid, query, calls from | 1
(18 rows)
Example 2: Shows the different username for the queries.
postgres=# select userid::regrole, datname, substr(query,0, 50) as query, calls from pg_stat_monitor, pg_database WHERE dbid = oid;
userid | datname | query | calls
----------+----------+---------------------------------------------------+-------
vagrant | postgres | select userid::regrole, datname, substr(query,$1, | 1
vagrant | test_db | insert into bar values($1) | 1
vagrant | postgres | insert into bar values($1) | 1
vagrant | test_db | select * from bar | 1
postgres | postgres | insert into bar values($1) | 1
(5 rows)
Example 3: Shows the differen database involved in the queries.
postgres=# select userid::regrole, datname, substr(query,0, 50) as query, calls from pg_stat_monitor, pg_database WHERE dbid = oid;
userid | datname | query | calls
---------+----------+---------------------------------------------------+-------
vagrant | postgres | select userid::regrole, datname, substr(query,$1, | 0
vagrant | test_db | insert into bar values($1) | 1
vagrant | test_db | select * from bar | 1
(3 rows)
Example 4: Shows the connected application_name.
postgres=# select application_name, query from pg_stat_monitor;
application_name | query
------------------+------------------------------------------------------------------------------------------------------
pgbench | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2
pgbench | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
pgbench | vacuum pgbench_tellers
pgbench | SELECT abalance FROM pgbench_accounts WHERE aid = $1
pgbench | END
pgbench | select count(*) from pgbench_branches
pgbench | BEGIN
pgbench | INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES ($1, $2, $3, $4, CURRENT_TIMESTAMP)
psql | select application_name, query from pg_stat_monitor
pgbench | vacuum pgbench_branches
psql | select application_name query from pg_stat_monitor
pgbench | truncate pgbench_history
pgbench | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
(13 rows)
Error Messages / Error Codes and Error Level
elevel, sqlcode,message,: error level / sql code and log/warning/error message
postgres=# select substr(query,0,50) as query, decode_error_level(elevel)as elevel,sqlcode,calls, substr(message,0,50) message from pg_stat_monitor;
query | elevel | sqlcode | calls | message
---------------------------------------------------+--------+---------+-------+---------------------------------------------------
select substr(query,$1,$2) as query, decode_error | | 0 | 1 |
select bucket,substr(query,$1,$2),decode_error_le | | 0 | 3 |
| LOG | 0 | 1 | database system is ready to accept connections
select 1/0; | ERROR | 130 | 1 | division by zero
| LOG | 0 | 1 | database system was shut down at 2020-11-11 11:37
select $1/$2 | | 0 | 1 |
(6 rows)
Query Timing Information
total_time, min_time, max_time, mean_time: The total / minimum / maximum and mean time spent for the same query.
postgres=# select userid, total_time, min_time, max_time, mean_time, query from pg_stat_monitor;
userid | total_time | min_time | max_time | mean_time | query
--------+--------------------+--------------------+--------------------+--------------------+------------------------------------------------------------------
10 | 0.14 | 0.14 | 0.14 | 0.14 | select * from pg_stat_monitor_reset()
10 | 0.19 | 0.19 | 0.19 | 0.19 | select userid, dbid, queryid, query from pg_stat_monitor
10 | 0.30 | 0.13 | 0.16 | 0.15 | select bucket, bucket_start_time, query from pg_stat_monitor
10 | 0.29 | 0.29 | 0.29 | 0.29 | select userid, dbid, queryid, query, calls from pg_stat_monitor
10 | 11277.79 | 11277.79 | 11277.79 | 11277.79 | SELECT * FROM foo
Client IP address
client_ip: The IP address of the client that originated the query.
postgres=# select userid::regrole, datname, substr(query,0, 50) as query, calls,client_ip from pg_stat_monitor, pg_database WHERE dbid = oid;
userid | datname | query | calls | client_ip
---------+----------+---------------------------------------------------+-------+-----------
vagrant | postgres | UPDATE pgbench_branches SET bbalance = bbalance + | 1599 | 10.0.2.15
vagrant | postgres | select userid::regrole, datname, substr(query,$1, | 5 | 10.0.2.15
vagrant | postgres | UPDATE pgbench_accounts SET abalance = abalance + | 1599 | 10.0.2.15
vagrant | postgres | select userid::regrole, datname, substr(query,$1, | 1 | 127.0.0.1
vagrant | postgres | vacuum pgbench_tellers | 1 | 10.0.2.15
vagrant | postgres | SELECT abalance FROM pgbench_accounts WHERE aid = | 1599 | 10.0.2.15
vagrant | postgres | END | 1599 | 10.0.2.15
vagrant | postgres | select count(*) from pgbench_branches | 1 | 10.0.2.15
vagrant | postgres | BEGIN | 1599 | 10.0.2.15
vagrant | postgres | INSERT INTO pgbench_history (tid, bid, aid, delta | 1599 | 10.0.2.15
vagrant | postgres | vacuum pgbench_branches | 1 | 10.0.2.15
vagrant | postgres | truncate pgbench_history | 1 | 10.0.2.15
vagrant | postgres | UPDATE pgbench_tellers SET tbalance = tbalance + | 1599 | 10.0.2.15
Call Timings Histogram
resp_calls: Call histogram
postgres=# select resp_calls, query from pg_stat_monitor;
resp_calls | query
--------------------------------------------------+----------------------------------------------
{1," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 0"} | select client_ip, query from pg_stat_monitor
{3," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 1"} | select * from pg_stat_monitor_reset()
{3," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 0"," 1"} | SELECT * FROM foo
There are 10 timebase buckets of the time pg_stat_monitor.pgsm_respose_time_step in the field resp_calls. The value in the field shows how many queries run in that period of time.
Object Information.
relations: The list of tables involved in the query
Example 1: List all the table names involved in the query.
postgres=# select relations::oid[]::regclass[], query from pg_stat_monitor;
relations | query
--------------------+------------------------------------------------------------------------------------------------------
{pgbench_accounts} | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
{pgbench_accounts} | SELECT abalance FROM pgbench_accounts WHERE aid = $1
{pg_stat_monitor} | select relations::oid[]::regclass[], cmd_type,resp_calls,query from pg_stat_monitor
{pgbench_branches} | select count(*) from pgbench_branches
{pgbench_history} | INSERT INTO pgbench_history (tid, bid, aid, delta, mtime) VALUES ($1, $2, $3, $4, CURRENT_TIMESTAMP)
{foo,bar} | select * from foo,bar
(5 rows)
Example 2: List all the views and the name of table in the view. Here we have a view "test_view"
postgres=# \d+ test_view
View "public.test_view"
Column | Type | Collation | Nullable | Default | Storage | Description
--------+---------+-----------+----------+---------+---------+-------------
foo_a | integer | | | | plain |
bar_a | integer | | | | plain |
View definition:
SELECT f.a AS foo_a,
b.a AS bar_a
FROM foo f,
bar b;
Now when we query the pg_stat_monitor, it will shows the view name and also all the table names in the view.
postgres=# select relations::oid[]::regclass[], query from pg_stat_monitor;
relations | query
---------------------+------------------------------------------------------------------------------------------------------
{test_view,foo,bar} | select * from test_view
{foo,bar} | select * from foo,bar
(2 rows)
Query command Type (SELECT, INSERT, UPDATE OR DELETE)
cmd_type: List the command type of the query.
postgres=# select substr(query,0, 50) as query, cmd_type from pg_stat_monitor where elevel = 0;
query | cmd_type
---------------------------------------------------+-----------------
BEGIN | {INSERT}
vacuum pgbench_branches | {}
UPDATE pgbench_branches SET bbalance = bbalance + | {UPDATE,SELECT}
select substr(query,$1, $2) as query, cmd_type fr | {SELECT}
select count(*) from pgbench_branches | {SELECT}
select substr(query,$1, $2) as query, cmd_type fr | {}
UPDATE pgbench_accounts SET abalance = abalance + | {UPDATE,SELECT}
update test SET a = $1 | {UPDATE}
END | {INSERT}
INSERT INTO pgbench_history (tid, bid, aid, delta | {INSERT}
vacuum pgbench_tellers | {}
SELECT a from test for update | {UPDATE,SELECT}
SELECT abalance FROM pgbench_accounts WHERE aid = | {SELECT}
UPDATE pgbench_tellers SET tbalance = tbalance + | {UPDATE,SELECT}
truncate pgbench_history | {}
(15 rows)
Copyright Notice
Copyright (c) 2006 - 2020, Percona LLC.