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Manual Reference Pages  -  PERCONA-TOOLKIT (1)

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percona-toolkit - Advanced command-line tools for MySQL



Percona Toolkit is a collection of advanced command-line tools used by Percona (<>) support staff to perform a variety of MySQL and system tasks that are too difficult or complex to perform manually.

These tools are ideal alternatives to private or one-off scripts because they are professionally developed, formally tested, and fully documented. They are also fully self-contained, so installation is quick and easy and no libraries are installed.

Percona Toolkit is derived from Maatkit and Aspersa, two of the best-known toolkits for MySQL server administration. It is developed and supported by Percona. For more information and other free, open-source software developed by Percona, visit <>.


This release of Percona Toolkit includes the following tools:
pt-align Align output from other tools to columns.
pt-archiver Archive rows from a MySQL table into another table or a file.
pt-config-diff Diff MySQL configuration files and server variables.
pt-deadlock-logger Log MySQL deadlocks.
pt-diskstats An interactive I/O monitoring tool for GNU/Linux.
pt-duplicate-key-checker Find duplicate indexes and foreign keys on MySQL tables.
pt-fifo-split Split files and pipe lines to a fifo without really splitting.
pt-find Find MySQL tables and execute actions, like GNU find.
pt-fingerprint Convert queries into fingerprints.
pt-fk-error-logger Log MySQL foreign key errors.
pt-heartbeat Monitor MySQL replication delay.
pt-index-usage Read queries from a log and analyze how they use indexes.
pt-ioprofile Watch process IO and print a table of file and I/O activity.
pt-kill Kill MySQL queries that match certain criteria.
pt-mext Look at many samples of MySQL SHOW GLOBAL STATUS side-by-side.
pt-mysql-summary Summarize MySQL information nicely.
pt-online-schema-change ALTER tables without locking them.
pt-pmp Aggregate GDB stack traces for a selected program.
pt-query-digest Analyze MySQL queries from logs, processlist, and tcpdump.
pt-show-grants Canonicalize and print MySQL grants so you can effectively replicate, compare and version-control them.
pt-sift Browses files created by pt-stalk.
pt-slave-delay Make a MySQL slave server lag behind its master.
pt-slave-find Find and print replication hierarchy tree of MySQL slaves.
pt-slave-restart Watch and restart MySQL replication after errors.
pt-stalk Collect forensic data about MySQL when problems occur.
pt-summary Summarize system information nicely.
pt-table-checksum Verify MySQL replication integrity.
pt-table-sync Synchronize MySQL table data efficiently.
pt-table-usage Analyze how queries use tables.
pt-upgrade Verify that query results are identical on different servers.
pt-variable-advisor Analyze MySQL variables and advise on possible problems.
pt-visual-explain Format EXPLAIN output as a tree.
For more free, open-source software developed Percona, visit <>.


Tool options use standard types (int, string, etc.) as well as these special types:
time Time values are seconds by default. For example, --run-time 60 means 60 seconds. Time values support an optional suffix: s (seconds), m (minutes), h (hours), d (days). --run-time 1m means 1 minute (the same as 60 seconds).
size Size values are bytes by default. For example, --disk-space-free 1024 means 1 Kibibyte. Size values support an optional suffix: k (Kibibyte), M (Mebibyte), G (Gibibyte).
Hash, hash, Array, array Hash, hash, Array, and array values are comma-separated lists of values. For example, --ignore-tables foo,bar ignores tables foo and bar.


Percona Toolkit tools can read options from configuration files. The configuration file syntax is simple and direct, and bears some resemblances to the MySQL command-line client tools. The configuration files all follow the same conventions.

Internally, what actually happens is that the lines are read from the file and then added as command-line options and arguments to the tool, so just think of the configuration files as a way to write your command lines.


The syntax of the configuration files is as follows:
o Whitespace followed by a hash sign (#) signifies that the rest of the line is a comment. This is deleted. For example:
o Whitespace is stripped from the beginning and end of all lines.
o Empty lines are ignored.
o Each line is permitted to be in either of the following formats:


Do not prefix the option with --. Do not quote the values, even if it has spaces; value are literal. Whitespace around the equals sign is deleted during processing.

o Only long options are recognized.
o A line containing only two hyphens signals the end of option parsing. Any further lines are interpreted as additional arguments (not options) to the program.


This config file for pt-stalk,

  # Config for pt-stalk
  cycles=2  # trigger if problem seen twice in a row
  --user daniel

is equivalent to this command line:

  pt-stalk --variable Threads_connected --cycles 2 -- --user daniel

Options after -- are passed literally to mysql and mysqladmin.


The tools read several configuration files in order:
1. The global Percona Toolkit configuration file, /etc/percona-toolkit/percona-toolkit.conf. All tools read this file, so you should only add options to it that you want to apply to all tools.
2. The global tool-specific configuration file, /etc/percona-toolkit/TOOL.conf, where TOOL is a tool name like pt-query-digest. This file is named after the specific tool you’re using, so you can add options that apply only to that tool.
3. The user’s own Percona Toolkit configuration file, $HOME/.percona-toolkit.conf. All tools read this file, so you should only add options to it that you want to apply to all tools.
4. The user’s tool-specific configuration file, $HOME/.TOOL.conf, where TOOL is a tool name like pt-query-digest. This file is named after the specific tool you’re using, so you can add options that apply only to that tool.


There is a special --config option, which lets you specify which configuration files Percona Toolkit should read. You specify a comma-separated list of files. However, its behavior is not like other command-line options. It must be given <B>firstB> on the command line, before any other options. If you try to specify it anywhere else, it will cause an error. Also, you cannot specify --config=/path/to/file; you must specify the option and the path to the file separated by whitespace without an equal sign between them, like:

  --config /path/to/file

If you don’t want any configuration files at all, specify --config to provide an empty list of files.


Percona Toolkit tools use DSNs to specify how to create a DBD connection to a MySQL server. A DSN is a comma-separated string of key=value parts, like:


The standard key parts are shown below, but some tools add additional key parts. See each tool’s documentation for details.

Some tools do not use DSNs but still connect to MySQL using options like --host, --user, and --password. Such tools uses these options to create a DSN automatically, behind the scenes.

Other tools uses both DSNs and options like the ones above. The options provide defaults for all DSNs that do not specify the option’s corresponding key part. For example, if DSN h=host1 and option --port=12345 are specified, then the tool automatically adds P=12345 to DSN.


DSNs are usually specified on the command line, so shell quoting and escaping must be taken into account. Special characters, like asterisk (*), need to be quoted and/or escaped properly to be passed as literal characters in DSN values.

Since DSN parts are separated by commas, literal commas in DSN values must be escaped with a single backslash (\). And since a backslash is the escape character for most shells, two backslashes are required to pass a literal backslash. For example, if the username is literally my,name, it must be specified as my\\,name on most shells. This applies to DSNs and DSN-related options like --user.


Many of the tools add more parts to DSNs for special purposes, and sometimes override parts to make them do something slightly different. However, all the tools support at least the following:
A Default character set for the connection (SET NAMES).

Enables character set settings in Perl and MySQL. 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. Other values set binmode on STDOUT without the utf8 layer and run SET NAMES after connecting to MySQL.

Unfortunately, there is no way from within Perl itself to specify the client library’s character set. SET NAMES only affects the server; if the client library’s settings don’t match, there could be problems. You can use the defaults file to specify the client library’s character set, however. See the description of the F part below.

D Default database to use when connecting. Tools may USE a different databases while running.
F Defaults file for the MySQL client library (the C client library used by DBD::mysql, not Percona Toolkit itself). All tools all read the [client] section within the defaults file. If you omit this, the standard defaults files will be read in the usual order. Standard varies from system to system, because the filenames to read are compiled into the client library. On Debian systems, for example, it’s usually /etc/mysql/my.cnf then ~/.my.cnf. If you place the following in ~/.my.cnf, you won’t have to specify your MySQL username and password on the command line:


Omitting the F part is usually the right thing to do. As long as you have configured your ~/.my.cnf correctly, that will result in tools connecting automatically without needing a username or password.

You can also specify a default character set in the defaults file. Unlike the A part described above, this will actually instruct the client library (DBD::mysql) to change the character set it uses internally, which cannot be accomplished any other way.

h MySQL hostname or IP address to connect to.
L Explicitly enable LOAD DATA LOCAL INFILE.

For some reason, some vendors compile libmysql without the --enable-local-infile option, which disables the statement. This can lead to weird situations, like the server allowing LOCAL INFILE, but the client throwing exceptions if it’s used.

However, as long as the server allows LOAD DATA, clients can easily re-enable it; see <> and <>. This option does exactly that.

p MySQL password to use when connecting.
P Port number to use for the connection. Note that the usual special-case behaviors apply: if you specify localhost as your hostname on Unix systems, the connection actually uses a socket file, not a TCP/IP connection, and thus ignores the port.
S MySQL socket file to use for the connection (on Unix systems).
u MySQL username to use when connecting, if not current system user.


Many of the tools will let you specify a DSN as a single word, without any key=value syntax. This is called a ’bareword’. How this is handled is tool-specific, but it is usually interpreted as the h part. The tool’s --help output will tell you the behavior for that tool.


Many tools will let you propagate values from one DSN to the next, so you don’t have to specify all the parts for each DSN. For example, if you want to specify a username and password for each DSN, you can connect to three hosts as follows:

 h=host1,u=fred,p=wilma host2 host3

This is tool-specific.


The environment variable PTDEBUG enables verbose debugging output to STDERR. To enable debugging and capture all output to a file, run the tool like:

   PTDEBUG=1 pt-table-checksum ... > FILE 2>&1

Be careful: debugging output is voluminous and can generate several megabytes of output.


Most tools require:
o Perl v5.8 or newer
o Bash v3 or newer
o Core Perl modules like Time::HiRes
Tools that connect to MySQL require:
o Perl modules DBI and DBD::mysql
o MySQL 5.0 or newer
Percona Toolkit officially supports and is tested on many popular Linux distributions and MySQL 5.0 through 5.6; see for the list of supported platforms and versions.


Please report bugs at <>. Include the following information in your bug report:
o Complete command-line used to run the tool
o Tool --version
o MySQL version of all servers involved
o Output from the tool including STDERR
o Input files (log/dump/config files, etc.)
If possible, include debugging output by running the tool with PTDEBUG; see ENVIRONMENT.


Baron Schwartz Baron created Maatkit, from which Percona Toolkit was forked. Many of the tools and modules were originally written by Baron.
Daniel Nichter Daniel has been the project’s lead developer since 2008. He is employed by Percona.
Frank Cizmich Frank is a full-time Percona Toolkit developer employed by Percona.
Others Many people have contributed code over the years. See each tool’s AUTHORS section for details.


Percona Toolkit is copyright 2011-2015 Percona LLC and/or its affiliates, et al. See each program’s documentation for complete copyright notices.


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.


Percona Toolkit v2.2.14 released 2015-04-10
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