User statistics¶
This feature adds several INFORMATION_SCHEMA tables, several commands, and the userstat variable. The tables and commands can be used to understand the server activity better and identify the source of the load.
The functionality is disabled by default and must be enabled by setting userstat to ON. It works by keeping several hash tables in memory. To avoid contention over global mutexes, each connection has its own local statistics, which are occasionally merged into the global statistics, and the local statistics are then reset to 0.
System variables¶
userstat¶
| Option | Description |
|---|---|
| Command-line | Yes |
| Config file | Yes |
| Scope | Global |
| Dynamic | Yes |
| Data type | BOOLEAN |
| Default | OFF |
| Range | ON/OFF |
Enables or disables collection of statistics. The default is OFF, meaning no statistics are gathered. This is to ensure that the statistics collection doesn’t cause any extra load on the server unless desired.
thread_statistics¶
| Option | Description |
|---|---|
| Command-line | Yes |
| Config file | Yes |
| Scope | Global |
| Dynamic | Yes |
| Data type | BOOLEAN |
| Default | OFF |
| Range | ON/OFF |
Enables or disables collection of thread statistics. The default is OFF, meaning no thread statistics are gathered. This is to ensure that the statistics collection doesn’t cause any extra load on the server unless desired. The variable userstat must be enabled as well in order for thread statistics to be collected.
INFORMATION_SCHEMA Tables¶
INFORMATION_SCHEMA.CLIENT_STATISTICS¶
| Column Name | Description |
|---|---|
| ‘CLIENT’ | ‘The IP address or hostname from which the connection originated.’ |
| ‘TOTAL_CONNECTIONS’ | ‘The number of connections created for this client.’ |
| ‘CONCURRENT_CONNECTIONS’ | ‘The number of concurrent connections for this client.’ |
| ‘CONNECTED_TIME’ | ‘The cumulative number of seconds elapsed while there were connections from this client.’ |
| ‘BUSY_TIME’ | ‘The cumulative number of seconds there was activity on connections from this client.’ |
| ‘CPU_TIME’ | ‘The cumulative CPU time elapsed, in seconds, while servicing this client’s connections.’ |
| ‘BYTES_RECEIVED’ | ‘The number of bytes received from this client’s connections.’ |
| ‘BYTES_SENT’ | ‘The number of bytes sent to this client’s connections.’ |
| ‘BINLOG_BYTES_WRITTEN’ | ‘The number of bytes written to the binary log from this client’s connections.’ |
| ‘ROWS_FETCHED’ | ‘The number of rows fetched by this client’s connections.’ |
| ‘ROWS_UPDATED’ | ‘The number of rows updated by this client’s connections.’ |
| ‘TABLE_ROWS_READ’ | ‘The number of rows read from tables by this client’s connections. (It may be different from ROWS_FETCHED.)’ |
| ‘SELECT_COMMANDS’ | ‘The number of SELECT commands executed from this client’s connections.’ |
| ‘UPDATE_COMMANDS’ | ‘The number of UPDATE commands executed from this client’s connections.’ |
| ‘OTHER_COMMANDS’ | ‘The number of other commands executed from this client’s connections.’ |
| ‘COMMIT_TRANSACTIONS’ | ‘The number of COMMIT commands issued by this client’s connections.’ |
| ‘ROLLBACK_TRANSACTIONS’ | ‘The number of ROLLBACK commands issued by this client’s connections.’ |
| ‘DENIED_CONNECTIONS’ | ‘The number of connections denied to this client.’ |
| ‘LOST_CONNECTIONS’ | ‘The number of this client’s connections that were terminated uncleanly.’ |
| ‘ACCESS_DENIED’ | ‘The number of times this client’s connections issued commands that were denied.’ |
| ‘EMPTY_QUERIES’ | ‘The number of times this client’s connections sent empty queries to the server.’ |
This table holds statistics about client connections. The Percona version of the feature restricts this table’s visibility to users who have the SUPER or PROCESS privilege.
For example:
mysql>SELECT * FROM INFORMATION_SCHEMA.CLIENT_STATISTICS\G
Expected output
*************************** 1. row ***************************
CLIENT: 10.1.12.30
TOTAL_CONNECTIONS: 20
CONCURRENT_CONNECTIONS: 0
CONNECTED_TIME: 0
BUSY_TIME: 93
CPU_TIME: 48
BYTES_RECEIVED: 5031
BYTES_SENT: 276926
BINLOG_BYTES_WRITTEN: 217
ROWS_FETCHED: 81
ROWS_UPDATED: 0
TABLE_ROWS_READ: 52836023
SELECT_COMMANDS: 26
UPDATE_COMMANDS: 1
OTHER_COMMANDS: 145
COMMIT_TRANSACTIONS: 1
ROLLBACK_TRANSACTIONS: 0
DENIED_CONNECTIONS: 0
LOST_CONNECTIONS: 0
ACCESS_DENIED: 0
EMPTY_QUERIES: 0
INFORMATION_SCHEMA tables¶
INFORMATION_SCHEMA.INDEX_STATISTICS¶
| Column Name | Description |
|---|---|
| ‘TABLE_SCHEMA’ | ‘The schema (database) name.’ |
| ‘TABLE_NAME’ | ‘The table name.’ |
| ‘INDEX_NAME’ | ‘The index name (as visible in SHOW CREATE TABLE).’ |
| ‘ROWS_READ’ | ‘The number of rows read from this index.’ |
This table shows statistics on index usage. An older version of the feature contained a single column that had the TABLE_SCHEMA, TABLE_NAME, and INDEX_NAME columns concatenated together. The Percona version of the feature separates these into three columns. Users can see entries only for tables to which they have SELECT access.
This table makes it possible to do many things that were difficult or impossible previously. For example, you can use it to find unused indexes and generate DROP commands to remove them.
Example:
mysql> SELECT * FROM INFORMATION_SCHEMA.INDEX_STATISTICS WHERE TABLE_NAME='tables_priv';
Expected output
+--------------+-----------------------+--------------------+-----------+
| TABLE_SCHEMA | TABLE_NAME | INDEX_NAME | ROWS_READ |
+--------------+-----------------------+--------------------+-----------+
| mysql | tables_priv | PRIMARY | 2 |
+--------------+-----------------------+--------------------+-----------+
Note
The current implementation of index statistics doesn’t support partitioned tables.
INFORMATION_SCHEMA.TABLE_STATISTICS¶
| Column Name | Description |
|---|---|
| ‘TABLE_SCHEMA’ | ‘The schema (database) name.’ |
| ‘TABLE_NAME’ | ‘The table name.’ |
| ‘ROWS_READ’ | ‘The number of rows read from the table.’ |
| ‘ROWS_CHANGED’ | ‘The number of rows changed in the table.’ |
| ‘ROWS_CHANGED_X_INDEXES’ | ‘The number of rows changed in the table, multiplied by the number of indexes changed.’ |
This table is similar in function to the INDEX_STATISTICS table.
For example:
mysql> SELECT * FROM INFORMATION_SCHEMA.TABLE_STATISTICS WHERE TABLE_NAME=``tables_priv``;
Expected output
+--------------+-------------------------------+-----------+--------------+------------------------+
| TABLE_SCHEMA | TABLE_NAME | ROWS_READ | ROWS_CHANGED | ROWS_CHANGED_X_INDEXES |
+--------------+-------------------------------+-----------+--------------+------------------------+
| mysql | tables_priv | 2 | 0 | 0 |
+--------------+-------------------------------+-----------+--------------+------------------------+
Note
The current implementation of table statistics doesn’t support partitioned tables.
INFORMATION_SCHEMA.THREAD_STATISTICS¶
| Column Name | Description |
|---|---|
| ‘THREAD_ID’ | ‘Thread ID’ |
| ‘TOTAL_CONNECTIONS’ | ‘The number of connections created from this thread.’ |
| ‘CONNECTED_TIME’ | ‘The cumulative number of seconds elapsed while there were connections from this thread.’ |
| ‘BUSY_TIME’ | ‘The cumulative number of seconds there was activity from this thread.’ |
| ‘CPU_TIME’ | ‘The cumulative CPU time elapsed while servicing this thread.’ |
| ‘BYTES_RECEIVED’ | ‘The number of bytes received from this thread.’ |
| ‘BYTES_SENT’ | ‘The number of bytes sent to this thread.’ |
| ‘BINLOG_BYTES_WRITTEN’ | ‘The number of bytes written to the binary log from this thread.’ |
| ‘ROWS_FETCHED’ | ‘The number of rows fetched by this thread.’ |
| ‘ROWS_UPDATED’ | ‘The number of rows updated by this thread.’ |
| ‘TABLE_ROWS_READ’ | ‘The number of rows read from tables by this tread.’ |
| ‘SELECT_COMMANDS’ | ‘The number of SELECT commands executed from this thread.’ |
| ‘UPDATE_COMMANDS’ | ‘The number of UPDATE commands executed from this thread.’ |
| ‘OTHER_COMMANDS’ | ‘The number of other commands executed from this thread.’ |
| ‘COMMIT_TRANSACTIONS’ | ‘The number of COMMIT commands issued by this thread.’ |
| ‘ROLLBACK_TRANSACTIONS’ | ‘The number of ROLLBACK commands issued by this thread.’ |
| ‘DENIED_CONNECTIONS’ | ‘The number of connections denied to this thread.’ |
| ‘LOST_CONNECTIONS’ | ‘The number of thread connections that were terminated uncleanly.’ |
| ‘ACCESS_DENIED’ | ‘The number of times this thread issued commands that were denied.’ |
| ‘EMPTY_QUERIES’ | ‘The number of times this thread sent empty queries to the server.’ |
| ‘TOTAL_SSL_CONNECTIONS’ | ‘The number of thread connections that used SSL.’ |
In order for this table to be populated with statistics, the additional variable thread_statistics should be set to ON.
INFORMATION_SCHEMA.USER_STATISTICS¶
| Column Name | Description |
|---|---|
| ‘USER’ | ‘The username. The value #mysql_system_user# appears when there is no username (such as for the replica SQL thread).’ |
| ‘TOTAL_CONNECTIONS’ | ‘The number of connections created from this user.’ |
| ‘CONCURRENT_CONNECTIONS’ | ‘The number of concurrent connections for this user.’ |
| ‘CONNECTED_TIME’ | ‘The cumulative number of seconds elapsed while there were connections from this user.’ |
| ‘BUSY_TIME’ | ‘The cumulative number of seconds there was activity on connections from this user.’ |
| ‘CPU_TIME’ | ‘The cumulative CPU time elapsed, in seconds, while servicing this user’s connections.’ |
| ‘BYTES_RECEIVED’ | ‘The number of bytes received from this user’s connections.’ |
| ‘BYTES_SENT’ | ‘The number of bytes sent to this user’s connections.’ |
| ‘BINLOG_BYTES_WRITTEN’ | ‘The number of bytes written to the binary log from this user’s connections.’ |
| ‘ROWS_FETCHED’ | ‘The number of rows fetched by this user’s connections.’ |
| ‘ROWS_UPDATED’ | ‘The number of rows updated by this user’s connections.’ |
| ‘TABLE_ROWS_READ’ | ‘The number of rows read from tables by this user’s connections. (It may be different from ROWS_FETCHED.)’ |
| ‘SELECT_COMMANDS’ | ‘The number of SELECT commands executed from this user’s connections.’ |
| ‘UPDATE_COMMANDS’ | ‘The number of UPDATE commands executed from this user’s connections.’ |
| ‘OTHER_COMMANDS’ | ‘The number of other commands executed from this user’s connections.’ |
| ‘COMMIT_TRANSACTIONS’ | ‘The number of COMMIT commands issued by this user’s connections.’ |
| ‘ROLLBACK_TRANSACTIONS’ | ‘The number of ROLLBACK commands issued by this user’s connections.’ |
| ‘DENIED_CONNECTIONS’ | ‘The number of connections denied to this user.’ |
| ‘LOST_CONNECTIONS’ | ‘The number of this user’s connections that were terminated uncleanly.’ |
| ‘ACCESS_DENIED’ | ‘The number of times this user’s connections issued commands that were denied.’ |
| ‘EMPTY_QUERIES’ | ‘The number of times this user’s connections sent empty queries to the server.’ |
This table contains information about user activity. The Percona version of the patch restricts this table’s visibility to users who have the SUPER or PROCESS privilege.
The table gives answers to questions such as which users cause the most load, and whether any users are being abusive. It also lets you measure how close to capacity the server may be. For example, you can use it to find out whether replication is likely to start falling behind.
Example:
mysql>SELECT * FROM INFORMATION_SCHEMA.USER_STATISTICS\G
Expected output
*************************** 1. row ***************************
USER: root
TOTAL_CONNECTIONS: 5592
CONCURRENT_CONNECTIONS: 0
CONNECTED_TIME: 6844
BUSY_TIME: 179
CPU_TIME: 72
BYTES_RECEIVED: 603344
BYTES_SENT: 15663832
BINLOG_BYTES_WRITTEN: 217
ROWS_FETCHED: 9793
ROWS_UPDATED: 0
TABLE_ROWS_READ: 52836023
SELECT_COMMANDS: 9701
UPDATE_COMMANDS: 1
OTHER_COMMANDS: 2614
COMMIT_TRANSACTIONS: 1
ROLLBACK_TRANSACTIONS: 0
DENIED_CONNECTIONS: 0
LOST_CONNECTIONS: 0
ACCESS_DENIED: 0
EMPTY_QUERIES: 0
Commands Provided¶
-
FLUSH CLIENT_STATISTICS -
FLUSH INDEX_STATISTICS -
FLUSH TABLE_STATISTICS -
FLUSH THREAD_STATISTICS -
FLUSH USER_STATISTICS
These commands discard the specified type of stored statistical information.
-
SHOW CLIENT_STATISTICS -
SHOW INDEX_STATISTICS -
SHOW TABLE_STATISTICS -
SHOW THREAD_STATISTICS -
SHOW USER_STATISTICS
These commands are another way to display the information you can get from the INFORMATION_SCHEMA tables. The commands accept WHERE clauses. They also accept but ignore LIKE clauses.
Status Variables¶
Com_show_client_statistics¶
| Option | Description |
|---|---|
| Scope | Global/Session |
| Data type | numeric |
The Com_show_client_statistics statement counter variable indicates the number of times the statement SHOW CLIENT_STATISTICS has been executed.
Com_show_index_statistics¶
| Option | Description |
|---|---|
| Scope | Global/Session |
| Data type | numeric |
The Com_show_index_statistics statement counter variable indicates the number of times the statement SHOW INDEX_STATISTICS has been executed.
Com_show_table_statistics¶
| Option | Description |
|---|---|
| Scope | Global/Session |
| Data type | numeric |
The Com_show_table_statistics statement counter variable indicates the number of times the statement SHOW TABLE_STATISTICS has been executed.
Com_show_thread_statistics¶
| Option | Description |
|---|---|
| Scope | Global/Session |
| Data type | numeric |
The Com_show_thread_statistics statement counter variable indicates the number of times the statement SHOW THREAD_STATISTICS has been executed.
Com_show_user_statistics¶
| Option | Description |
|---|---|
| Scope | Global/Session |
| Data type | numeric |
The Com_show_user_statistics statement counter variable indicates the number of times the statement SHOW USER_STATISTICS has been executed.
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