SYNOPSIS

Split slow.log on Thread_id into 16 session files, save in ./sessions:

mk-log-player --split Thread_id --session-files 16 --base-dir ./sessions slow.log

Play all those sessions on host1, save results in ./results:

  mk-log-player --play ./sessions --base-dir ./results h=host1

Use mk-query-digest to summarize the results:

  mk-query-digest ./results/*

RISKS

The following section is included to inform users about the potential risks, whether known or unknown, of using this tool. The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs.

``--play'' is meant to load a server as much as possible, for stress-testing purposes. It is not designed to be used on production servers.

At the time of this release, we know of no bugs that could cause serious harm to users.

The authoritative source for updated information is always the online issue tracking system. Issues that affect this tool will be marked as such. You can see a list of such issues at the following URL: <http://www.maatkit.org/bugs/mk-log-player>.

See also ``BUGS'' for more information on filing bugs and getting help.

DESCRIPTION

mk-log-player does two things: it splits MySQL slow logs into session files and it plays (executes) queries in session files on a MySQL server. Only session files can be played; slow logs cannot be played directly without being split.

A session is a group of queries from the slow log that all share a common attribute, usually Thead_id. The common attribute is specified with ``--split''. Multiple sessions are saved into a single sesssion file. See ``--session-files'', ``--max-sessions'', ``--base-file-name'' and ``--base-dir''. These session files are played with ``--play''.

mk-log-player will ``--play'' session files in parallel using N number of ``--threads''. (They're not technically threads, but we call them that anyway.) Each thread will play all the sessions in its given session files. The sessions are played as fast as possible---there are no delays---because the goal is to stress-test and load-test the server. So be careful using this script on a production server!

Each ``--play'' thread writes its results to a separate file. These result files are in slow log format so they can be aggregated and summarized with mk-query-digest. See ``OUTPUT''.

OUTPUT

Both ``--split'' and ``--play'' have two outputs: status messages printed to STDOUT to let you know what the script is doing, and session or result files written to separate files saved in ``--base-dir''. You can suppress all output to STDOUT for each with ``--quiet'', or increase output with ``--verbose''.

The session files written by ``--split'' are simple text files containing queries grouped into sessions. For example:

  -- START SESSION 10
  use foo
  SELECT col FROM foo_tbl

The format of these session files is important: each query must be a single line separated by a single blank line. And the ``-- START SESSION'' comment tells mk-log-player where individual sessions begin and end so that ``--play'' can correctly fake Thread_id in its result files.

The result files written by ``--play'' are in slow log format with a minimal header: the only attributes printed are Thread_id, Query_time and Schema.

OPTIONS

Specify at least one of ``--play'', ``--split'' or ``--split-random''.

``--play'' and ``--split'' are mutually exclusive.

--ask-pass

group: Play

Prompt for a password when connecting to MySQL.

--base-dir

type: string; default: ./

Base directory for ``--split'' session files and ``--play'' result file.

--base-file-name

type: string; default: session

Base file name for ``--split'' session files and ``--play'' result file.

Each ``--split'' session file will be saved as <base-file-name>-N.txt, where N is a four digit, zero-padded session ID. For example: session-0003.txt.

Each ``--play'' result file will be saved as <base-file-name>-results-PID.txt, where PID is the process ID of the executing thread.

All files are saved in ``--base-dir''.

--charset

group: Play

short form: -A; type: string

Default character set. If the value is utf8, sets Perl's binmode on STDOUT to utf8, passes the mysql_enable_utf8 option to DBD::mysql, and runs SET NAMES UTF8 after connecting to MySQL. Any other value sets binmode on STDOUT without the utf8 layer, and runs SET NAMES after connecting to MySQL.

--config

type: Array

Read this comma-separated list of config files; if specified, this must be the first option on the command line.

--defaults-file

short form: -F; type: string

Only read mysql options from the given file.

--dry-run

Print which processes play which session files then exit.

--filter

type: string; group: Split

Discard ``--split'' events for which this Perl code doesn't return true.

This option only works with ``--split''.

This option is a string of Perl code or a file containing Perl code that gets compiled into a subroutine with one argument: $event. This is a hashref. If the given value is a readable file, then mk-log-player reads the entire file and uses its contents as the code. The file should not contain a shebang (#!/usr/bin/perl) line.

If the code returns true, the query is split; otherwise it is discarded. The code is the last statement in the subroutine other than "return $event". The subroutine template is:

  sub { $event = shift; filter && return $event; }

Filters given on the command line are wrapped inside parentheses like like "( filter )". For complex, multi-line filters, you must put the code inside a file so it will not be wrapped inside parentheses. Either way, the filter must produce syntactically valid code given the template. For example, an if-else branch given on the command line would not be valid:

  --filter 'if () { } else { }'  # WRONG

Since it's given on the command line, the if-else branch would be wrapped inside parentheses which is not syntactically valid. So to accomplish something more complex like this would require putting the code in a file, for example filter.txt:

  my $event_ok; if (...) { $event_ok=1; } else { $event_ok=0; } $event_ok

Then specify "--filter filter.txt" to read the code from filter.txt.

If the filter code won't compile, mk-log-player will die with an error. If the filter code does compile, an error may still occur at runtime if the code tries to do something wrong (like pattern match an undefined value). mk-log-player does not provide any safeguards so code carefully!

An example filter that discards everything but SELECT statements:

  --filter '$event->{arg} =~ m/^select/i'

This is compiled into a subroutine like the following:

  sub { $event = shift; ( $event->{arg} =~ m/^select/i ) && return $event; }

You can find an explanation of the structure of $event at <http://code.google.com/p/maatkit/wiki/EventAttributes>.

--help

Show help and exit.

--host

short form: -h; type: string; group: Play

Connect to host.

--iterations

type: int; default: 1; group: Play

How many times each thread should play all its session files.

--max-sessions

type: int; default: 5000000; group: Split

Maximum number of sessions to ``--split''.

By default, "mk-log-player" tries to split every session from the log file. For huge logs, however, this can result in millions of sessions. This option causes only the first N number of sessions to be saved. All sessions after this number are ignored, but sessions split before this number will continue to have their queries split even if those queries appear near the end of the log and after this number has been reached.

--only-select

group: Play

Play only SELECT and USE queries; ignore all others.

--password

short form: -p; type: string; group: Play

Password to use when connecting.

--pid

type: string

Create the given PID file. The file contains the process ID of the script. The PID file is removed when the script exits. Before starting, the script checks if the PID file already exists. If it does not, then the script creates and writes its own PID to it. If it does, then the script checks the following: if the file contains a PID and a process is running with that PID, then the script dies; or, if there is no process running with that PID, then the script overwrites the file with its own PID and starts; else, if the file contains no PID, then the script dies.

--play

type: string; group: Play

Play (execute) session files created by ``--split''.

The argument to play must be a commaxn-separated list of session files created by ``--split'' or a directory. If the argument is a directory, ALL files in that directory will be played.

--port

short form: -P; type: int; group: Play

Port number to use for connection.

--print

group: Play

Print queries instead of playing them; requires ``--play''.

You must also specify ``--play'' with ``--print''. Although the queries will not be executed, ``--play'' is required to specify which session files to read.

--quiet

Do not print anything; disables ``--verbose''.

--[no]results

default: yes

Print ``--play'' results to files in ``--base-dir''.

--session-files

type: int; default: 8; group: Split

Number of session files to create with ``--split''.

The number of session files should either be equal to the number of ``--threads'' you intend to ``--play'' or be an even multiple of ``--threads''. This number is important for maximum performance because it:
  * allows each thread to have roughly the same amount of sessions to play
  * avoids having to open/close many session files
  * avoids disk IO overhead by doing large sequential reads

You may want to increase this number beyond ``--threads'' if each session file becomes too large. For example, splitting a 20G log into 8 sessions files may yield roughly eight 2G session files.

See also ``--max-sessions''.

--set-vars

type: string; group: Play; default: wait_timeout=10000

Set these MySQL variables. Immediately after connecting to MySQL, this string will be appended to SET and executed.

--socket

short form: -S; type: string; group: Play

Socket file to use for connection.

--split

type: string; group: Split

Split log by given attribute to create session files.

Valid attributes are any which appear in the log: Thread_id, Schema, etc.

--split-random

group: Split

Split log without an attribute, write queries round-robin to session files.

This option, if specified, overrides ``--split'' and causes the log to be split query-by-query, writing each query to the next session file in round-robin style. If you don't care about ``sessions'' and just want to split a lot into N many session files and the relation or order of the queries does not matter, then use this option.

--threads

type: int; default: 2; group: Play

Number of threads used to play sessions concurrently.

Specifies the number of parallel processes to run. The default is 2. On GNU/Linux machines, the default is the number of times 'processor' appears in /proc/cpuinfo. On Windows, the default is read from the environment. In any case, the default is at least 2, even when there's only a single processor.

See also ``--session-files''.

--type

type: string; group: Split

The type of log to ``--split'' (default slowlog). The permitted types are

binlog

Split a binary log file.

genlog

Split a general log file.

slowlog

Split a log file in any varation of MySQL slow-log format.

--user

short form: -u; type: string; group: Play

User for login if not current user.

--verbose

short form: -v; cumulative: yes; default: 0

Increase verbosity; can specifiy multiple times.

This option is disabled by ``--quiet''.

--version

Show version and exit.

--wait-between-sessions

type: array; default: 0; group: Play

Not implemented yet.

The wait time is given in seconds with microsecond precision and can be either a single value or a range. A single value causes an exact wait; example: 0.010 = wait 10 milliseconds. A range causes a random wait between the given value times; example: 0.001,1 = random wait from 1 millisecond to 1 second.

--[no]warnings

default: no; group: Play

Print warnings about SQL errors such as invalid queries to STDERR.

DSN OPTIONS

These DSN options are used to create a DSN. Each option is given like "option=value". The options are case-sensitive, so P and p are not the same option. There cannot be whitespace before or after the "=" and if the value contains whitespace it must be quoted. DSN options are comma-separated. See the maatkit manpage for full details.

• A

  dsn: charset; copy: yes

  Default character set.

• D

  dsn: database; copy: yes

  Default database.

• F

  dsn: mysql_read_default_file; copy: yes

  Only read default options from the given file

• h

  dsn: host; copy: yes

  Connect to host.

• p

  dsn: password; copy: yes

  Password to use when connecting.

• P

  dsn: port; copy: yes

  Port number to use for connection.

• S

  dsn: mysql_socket; copy: yes

  Socket file to use for connection.

• u

  dsn: user; copy: yes

  User for login if not current user.

DOWNLOADING

You can download Maatkit from Google Code at <http://code.google.com/p/maatkit/>, or you can get any of the tools easily with a command like the following:

   wget http://www.maatkit.org/get/toolname
   or
   wget http://www.maatkit.org/trunk/toolname

Where "toolname" can be replaced with the name (or fragment of a name) of any of the Maatkit tools. Once downloaded, they're ready to run; no installation is needed. The first URL gets the latest released version of the tool, and the second gets the latest trunk code from Subversion.

   MKDEBUG=1 mk-....

SYSTEM REQUIREMENTS

You need Perl and some core packages that ought to be installed in any reasonably new version of Perl.

COPYRIGHT, LICENSE AND WARRANTY

This program is copyright 2008-2010 Percona Inc. Feedback and improvements are welcome.

THIS PROGRAM IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2; OR the Perl Artistic License. On UNIX and similar systems, you can issue `man perlgpl' or `man perlartistic' to read these licenses.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.

AUTHOR

Daniel Nichter

ABOUT MAATKIT

This tool is part of Maatkit, a toolkit for power users of MySQL. Maatkit was created by Baron Schwartz; Baron and Daniel Nichter are the primary code contributors. Both are employed by Percona. Financial support for Maatkit development is primarily provided by Percona and its clients.

VERSION

This manual page documents Ver 1.0.8 Distrib 6652 $Revision: 6644 $.