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.

Other Information

• Author/Origin:

  Google; Percona added the INFORMATION_SCHEMA tables and the userstat_running variable.

System Variables

variable userstat_running

Version Info:

• 5.1.49-rel11.3 – variable introduced

Command Line:

Yes

Config File:

Yes

Scope:

Global

Dynamic:

Yes

Variable Type:

BOOLEAN

Default Value:

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.

INFORMATION_SCHEMA Tables

table INFORMATION_SCHEMA.CLIENT_STATISTICS

Columns:

• 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 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.

Example:

mysql> SELECT * FROM INFORMATION_SCHEMA.CLIENT_STATISTICS\G
*************************** 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

table INFORMATION_SCHEMA.INDEX_STATISTICS

Columns:

• 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. If the index has not been used it won’t be in this table.

Example:

mysql> SELECT * FROM INFORMATION_SCHEMA.INDEX_STATISTICS
   WHERE TABLE_NAME='tables_priv';
+--------------+-----------------------+--------------------+-----------+
| TABLE_SCHEMA | TABLE_NAME            | INDEX_NAME         | ROWS_READ |
+--------------+-----------------------+--------------------+-----------+
| mysql        | tables_priv           | PRIMARY            |         2 |
+--------------+-----------------------+--------------------+-----------+

table INFORMATION_SCHEMA.TABLE_STATISTICS

Columns:

• 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.

Example:

mysql> SELECT * FROM INFORMATION_SCHEMA.TABLE_STATISTICS
   WHERE TABLE_NAME=``tables_priv``;
+--------------+-------------------------------+-----------+--------------+------------------------+
| TABLE_SCHEMA | TABLE_NAME                    | ROWS_READ | ROWS_CHANGED | ROWS_CHANGED_X_INDEXES |
+--------------+-------------------------------+-----------+--------------+------------------------+
| mysql        | tables_priv                   |         2 |            0 |                      0 |
+--------------+-------------------------------+-----------+--------------+------------------------+

table INFORMATION_SCHEMA.THREAD_STATISTICS

Columns:

• THREAD_ID – ID of the thread.
• TOTAL_CONNECTIONS – The number of connections created from this thread.
• CONCURRENT_CONNECTIONS – The number of concurrent connections 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.

In order for this table to be populated with statistics, additional variable thread_statistics should be set to ON.

table INFORMATION_SCHEMA.USER_STATISTICS

Columns:

• USER – The username. The value #mysql_system_user# appears when there is no username (such as for the slave SQL thread).
• TOTAL_CONNECTIONS – The number of connections created for 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 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
*************************** 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.