View MySQL connections and status

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1. View the number of MySQL connections

Log on to the MySQL command line and use the following command to view a list of processes that are currently in a disconnected state;

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1. Show full processlist;

If the full option is not added, up to 100 records are displayed.

If you log in as root, you can see the current connection for all users. If you are a normal account, you can only see the connection you are occupying.

When you debug a program, you can query the number of connections (as user logins in the application) by using this command if you suspect that a DB connection has not been released in your application. If the program runs more and more connections, you can tell that the DB resource in the program is not released.

To modify the maximum number of connections allowed, the my.cnf file under/mysql-advanced-5.6.19-win32/mysql-test/suite/ndb/should be modified under the win environment.

Set-variable=max_user_connections=30 This is the number of single-user connections
set-variable=max_connections=800 This is the global limit number of connections

2. View MySQL Database status

Command:

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1. Show status;

This command prints out all the states of the DB, where specific items can be added like '% variable name% '

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1. Show status like '% variable name% ';

Common variables are:

Aborted_clients the number of connections that have been discarded because the client did not properly close the connection already dead. Aborted_connects the number of times the connection to the MySQL server has failed. Connections the number of attempts to connect to the MySQL server. Created_tmp_tables the number of suppressed temporary tables that have been created when the statement is executed. Delayed_insert_threads the number of deferred plug-in processor threads being used. Delayed_writes the number of rows written with the insert Delayed. Delayed_errors the number of rows written with insert Delayed for some errors (possibly repeating key values). Flush_commands the number of times the flush command was executed. Handler_delete the number of times a row was requested to be deleted from a table. The number of times the Handler_read_first request reads the first row in the table. The Handler_read_key requests a number based on the key read line. The number of times a handler_read_next request reads into a row based on one key. The number of times a HANDLER_READ_RND request reads into a row based on a fixed position. Handler_update the number of times a row in the table was requested to be updated. The number of times the Handler_write request inserts a row into the table. key_blocks_used the number of blocks used for the keyword cache. Key_read_requests the number of times a key value was requested to be read from the cache. Key_reads the number of times a key value has been physically read from disk. Key_write_requests requests a keyword block to be written to the cache count. Key_writes the number of times a key-value block is physically written to disk. Max_used_connections the maximum number of connections that are used at the same time. Not_flushed_key_blocks a key block that has been changed in the key cache but has not been emptied to disk. Not_flushed_delayed_rows the number of rows waiting to be written in the Insert delay queue. Open_tables the number of open tables. Open_files the number of open files. Open_streams the number of open streams (primarily for logging) Opened_tables the number of tables that have already been opened. Questions the number of queries destined for the server. Slow_queries the number of queries that will take more than long_query_time time. threads_connected the number of connections currently open. Threads_running notThe number of threads in the sleep. Uptime How many seconds the server has worked.

View MySQL connections and status