mtop [--host={mysql_host}] [--dbuser={mysql_user}]
        [--password={mysqluser_pw}] [--seconds={refresh}] [--[no]idle]
        [--filter-user={regex}] [--filter-host={regex}] [--filter-db={regex}]
        [--filter-command={regex}] [--filter-state={regex}] [--filter-info={{regex}}]
        [--fold-select-columns]
        [--user={user}] [--manualrefresh] [--slow={seconds}] [--vs|veryslow={seconds}]
        [--vvs|veryveryslow={seconds}]

    mtop --help

    mtop --version

Normally, run as a console program this will allow you to see errant or badly optimized queries as they will stay on the screen for a while. However, if you are hunting for short lived queries, running in the manualrefresh mode with a short refresh time will allow you to catch short lived queries as well.

The following keys are active while mtop is running:

    q - quit
    ? - help

    Filtering/display

    s - change the number of seconds to delay between updates
    m - toggle manual refresh mode on/off
    d - filter display with regular expression (user/host/db/command/state/info)
    F - fold/unfold column names in select statement display
    h - display process for only one host
    u - display process for only one user
    i - toggle all/non-Sleeping process display
    o - reverse the sort order

    Control/Detail

    k - kill processes; send a kill to a list of ids
    e - explain a process; show query optimizer info
    z - zoom in on a process; show sql statement detail
    f - flush stats (reset show status variables)
    t - show mysqld stats (show status/mysqladmin ext)
    T - show short/important status
    v - show mysqld variables (show variables/mysqladmin vars)
    r - show replication status for master/slaves

Main Screen

The main query screen shows the following information as well as the currently active queries (explanations are from the MySQL online manual and references refer to the section in the manual where the explanation came from):

n Threads: running, cached

The n Threads represents how many threads the mysqld has allocated. One thread is allocated for each user connection. Additional threads are allocated for replication.

Queries/slow: Total queries / Total SLOW QUERIES

The first number is the total number of queries sent to the server since the last 'flush status' or since server start. The second number is the number of queries that have taken more than long_query_time. See section 4.9.5 The Slow Query Log.

Cache Hit: Cache hit ratio

This is the percentage of times a key read is handled from the key buffer cache. See section 4.5.7.4 SHOW VARIABLES of the MySQL manual for more information.

Opened tables: tables opened

MySQL has a cache for open tables. If 'opened tables' is high, your cache may be too small. Look at the MySQL manual section: 5.4.7 How MySQL Opens and Closes Tables for further information.

RRN: Handler_read_rnd_next

Number of requests to read the next row in the datafile. This will be high if you are doing a lot of table scans. Generally this suggests that your tables are not properly indexed or that your queries are not written to take advantage of the indexes you have. (4.5.7.3)

TLW: Table_locks_waited

Number of times a table lock could not be acquired immediately and a wait was needed. If this is high, and you have performance problems, you should first optimise your queries, and then either split your table(s) or use replication. Available after 3.23.33. (4.5.7.3)

SFJ: Select_full_join

Number of joins without keys (If this is not 0, you should carefully check the indexes of your tables). (4.5.7.3)

SMP: Sort_merge_passes

Number of merges passes the sort algoritm have had to do. If this value is large you should consider increasing sort_buffer. (4.5.7.3)

QPS: Questions per second

The total number of sql commands handled by the MySQL server since startup or the last flush status command.

Statistics/Variables

When viewing the stats screen (t), the screen will refresh until a key is pressed at which point you will return to the main screen. The bottom of the stats screen is denoted with a line containing ---. If you do not see that line, resize your screen until you do.

The statistics screen has the following format:

    Stat:      total [avg per sec / instant per sec ]

For example:

    Questions:     720,672 [30/12]

The short/important status screen is a list of recommendations from the MySQL manual.

The first number is the total since startup or the last 'flush status'. The second number is the number per second since startup or flush. The last is the number per second since the last screen refresh.

The variables screen only shows the information once and returns to the main screen as the variables do not change after server startup.

Replication

The replication monitor screen looks for a master or slave server running on the currently monitored mysqld. If a master server is found, it then tries to connect to each slave connected to the master. Replication is shown for all masters and slaves found. Offsets from the master for each of the slaves is shown. Note: the offset may be less than zero because the slave position is checked after the master position. The offset shown is the number of queries in the binlog that the slave has to process before being caught up with the master.