MTOP(1) User Contributed Perl Documentation MTOP(1)NAMEmtop - Shows top mysql threads
SYNOPSISmtop [--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
DESCRIPTION
Shows the MySQL commands consuming the greatest time. By default, only
non-sleeping threads are shown, the --idle option shows idle threads.
While running several keys will affect the operation of mtop. Hitting
h or ? will show the available options.
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.
OPTIONS
All options can be abbreviated by their shortest unique abbreviation.
-?, --help
Show the help screen and exit.
-v, --version
Show the version number and exit.
-h {mysql_host}, --host={mysql_host}
By default, the mysqld on localhost is monitored. Specify an
alternate host with this option.
-dbu {mysql_user}, --dbuser={mysql_user}
By default, the user 'mysqltop' is used to connect to the database.
Specify an alternate user with this option.
-p {mysqluser_pw}, --password={mysqluser_pw}
By default, there is no password associated with the mysqltop user,
specify a password with this option.
-se {refresh}, --seconds={refresh}
The default screen refresh is 5 seconds.
-sl {seconds}, --slow={seconds}
The number of seconds before a slow query is highlighted. The
default is the server's long_query configuration variable.
-vs {seconds}, --veryslow={seconds}
The number of seconds before a very slow query is highlighted. The
default is the the --slow option * 2.
-vvs {seconds}, --veryveryslow={seconds}
The number of seconds before a very very slow query is highlighted.
The default is the the --slow option * 4.
-i, --[no]idle
By default, processes in the Sleep command state are not shown.
This option turns on display of idle threads.
-u {user}, --user={user}
Show only threads owned by this user.
-fu {regex_pattern}, --filter-user={regex_pattern}
-fh {regex_pattern}, --filter-host={regex_pattern}
-fd {regex_pattern}, --filter-db={regex_pattern}
-fs {regex_pattern}, --filter-state={regex_pattern}
-fc {regex_pattern}, --filter-command={regex_pattern}
-fi {regex_pattern}, --filter-info={regex_pattern}
Filter the display based on the regex_pattern provided. The
regex_pattern is a perl regular expression. The regular expression
match is done with case insensitivity.
For example, to only show select statements on the user table, use
the following:
--filter-info='select from user'
or, to be more forgiving for mutil-table joins and extra spaces,
use:
--filter-info='select\s+from\s+.*\buser\b.*where'
These same regular expression filters can be used with the
interactive d command. Be careful to escape any special shell
characters in the regex.
-m, --manualrefresh
In this mode, the screen only refreshes when the user hits a key on
the keyboard. The screen will refresh automatically until a query
is seen and then wait for further input. An uppercase M will
appear in the top right hand corner of the screen to indicate that
you are in this mode.
All options can be stored in initialization files. Command line
options override options stored in the initialization file(s). The
following files are checked for arguments: current direcotry .mtoprc,
home directory .mtoprc, /usr/local/etc/mtoprc, /etc/mtoprc. Options in
the former files override options in the later files.
The format of the initialization file is one option per line. Options
are specified just as they would be on the command line. They can be
abbreviated and use the one or two hyphen syntax. Comments and blank
lines are ignored. The following is an exmple .mtoprc file which sets
a user filter to user1 and sets the refresh rate to one second:
# Only look at 'user1'
-fu user1
--seconds=1 # refresh every one seconds
SETUP
The most convenient way to setup your system to use mtop is to create a
database user called mysqltop which has no password. For security
purposes, this user should have all privileges set to N except
Process_priv which must be set to Y.
To grant these privileges, execute the following from the MySQL command
prompt
For mysql 4.0.2 and greater:
mysql> grant super, reload, process on *.* to mysqltop;
mysql> grant super, reload, process on *.* to mysqltop@localhost;
mysql> flush privileges;
For mysql 3.x and 4.0.1:
mysql> grant reload, process on *.* to mysqltop;
mysql> grant reload, process on *.* to mysqltop@localhost;
mysql> flush privileges;
Notes:
· GRANT only works in MySQL 3.22.11 or later, for earlier versions
add the user manually and fix the permissions as noted above.
· The GRANT to mysqltop and mysqltop@localhost may be modified
depending upon which hosts you want to grant access from. In
general, you probably want to limit it to the hosts in your domain.
· The reload privilege is not required for mtop to do basic
monitoring. It is only needed if you wish to issue flush commands
from mtop. The super privilege is needed if you wish to kill
queries in mysql 4.0.2 versions and above. In 3.x, the process
privilege allows a user to terminate a query.
Initially, mtop does not connect to a specific database. Most commands
this program issues are non-database specific (SHOW FULL PROCESSLIST,
SHOW VARIABLES, KILL id). However, when database-specific commands are
needed, mtop will try to connect to the the required database and
prompt for a username/password if the default one fails.
To install mtop, run the following shell commands:
perl Makefile.PL
make
make install
The default {install_prefix} is /usr/local which means that mtop is
installed in /usr/local/bin/. To change this, run:
perl Makefile.PL --prefix={install_prefix}
or modify the PREFIX line in Makefile.PL.
Requires the following perl modules:
Module Available At
--------------------------------------------------------------------
Curses http://www.cpan.org/authors/id/WPS
DBI Distributed as Bundle::DBI: http://www.cpan.org/authors/id/TIMB
DBD::mysql http://www.cpan.org/authors/id/JWIED
Getopt::Long (Distributed with Perl 5)
Net::Domain Part of libnet: http://www.cpan.org/authors/id/GBARR/
AUTHOR
Marc Prewitt, Chelsea Networks <mprewitt@chelsea.net>
Copyright (C) 2002 Marc Prewitt/Chelsea Networks, under the GNU GPL.
mtop comes with ABSOLUTELY NO WARRANTY. This is free software, and you
are welcome to redistribute it under certain conditions; see the
COPYING file for details.
KNOWN BUGS
The cache hit ratio may look very low if your server receives more than
4 billion key_read_requests. This is due to a roll-over condition. If
that number exceeds 4 billion and change, it rolls over to 1. The
cache hit ratio is calculated as: 100 - (key_reads/key_read_requests) *
100.
If you are really trying to focus on the cache hit ratio, flush the
status variables with the mtop f command to reset both the key_reads
and key_read_requests.
Win2K telnet.exe - If you are using the Windows 2000 telnet program, it
defaults to ansi mode which doesn't work well with curses (in my
testing on Solaris 8). To work around this, set the terminal type to
vt100. To do this, issue the following command from the telnet prompt
before connecting to a host:
set term vt100
Alternatively, you can manually set your TERM environment variable to
vt100 after you are logged in.
TODO
Offer sorts by other columns
For the 'More:' paging, it would be nice to support 'Less' behaviour.
Add 'n' command and properly calculate number of lines on screen.
$Id: mtop.PL,v 1.61 2004/09/12 22:22:03 mdprewitt Exp $
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 2000:
'=end' without a target? (Should be "=end showsatus")
perl v5.20.2 2015-09-15 MTOP(1)
