=pod

=head1 NAME

percona-toolkit - Advanced command-line tools for MySQL

=head1 DESCRIPTION

Percona Toolkit is a collection of advanced command-line tools used by
Percona (L<http://www.percona.com/>) 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 L<http://www.percona.com/software/>.

=head1 TOOLS

This release of Percona Toolkit includes the following tools:

=over

=item pt-align

Align output from other tools to columns.

=item pt-archiver

Archive rows from a MySQL table into another table or a file.

=item pt-config-diff

Diff MySQL configuration files and server variables.

=item pt-deadlock-logger

Log MySQL deadlocks.

=item pt-diskstats

An interactive I/O monitoring tool for GNU/Linux.

=item pt-duplicate-key-checker

Find duplicate indexes and foreign keys on MySQL tables.

=item pt-fifo-split

Split files and pipe lines to a fifo without really splitting.

=item pt-find

Find MySQL tables and execute actions, like GNU find.

=item pt-fingerprint

Convert queries into fingerprints.

=item pt-fk-error-logger

Log MySQL foreign key errors.

=item pt-heartbeat

Monitor MySQL replication delay.

=item pt-index-usage

Read queries from a log and analyze how they use indexes.

=item pt-ioprofile

Watch process IO and print a table of file and I/O activity.

=item pt-kill

Kill MySQL queries that match certain criteria.

=item pt-mext

Look at many samples of MySQL C<SHOW GLOBAL STATUS> side-by-side.

=item pt-mysql-summary

Summarize MySQL information nicely.

=item pt-online-schema-change

ALTER tables without locking them.

=item pt-pmp

Aggregate GDB stack traces for a selected program.

=item pt-query-digest

Analyze MySQL queries from logs, processlist, and tcpdump.

=item pt-show-grants

Canonicalize and print MySQL grants so you can effectively replicate, compare and version-control them.

=item pt-sift

Browses files created by pt-stalk.

=item pt-slave-delay

Make a MySQL slave server lag behind its master.

=item pt-slave-find

Find and print replication hierarchy tree of MySQL slaves.

=item pt-slave-restart

Watch and restart MySQL replication after errors.

=item pt-stalk

Collect forensic data about MySQL when problems occur.

=item pt-summary

Summarize system information nicely.

=item pt-table-checksum

Verify MySQL replication integrity.

=item pt-table-sync

Synchronize MySQL table data efficiently.

=item pt-table-usage

Analyze how queries use tables.

=item pt-upgrade

Verify that query results are identical on different servers.

=item pt-variable-advisor

Analyze MySQL variables and advise on possible problems.

=item pt-visual-explain

Format EXPLAIN output as a tree.

=back

For more free, open-source software developed Percona, visit
L<http://www.percona.com/software/>.

=head1 SPECIAL OPTION TYPES

Tool options use standard types (C<int>, C<string>, etc.) as well as
these special types:

=over

=item time

Time values are seconds by default.  For example, C<--run-time 60> means
60 seconds.  Time values support an optional suffix: s (seconds),
m (minutes), h (hours), d (days).  C<--run-time 1m> means 1 minute
(the same as 60 seconds).

=item size

Size values are bytes by default.  For example, C<--disk-space-free 1024>
means 1 Kibibyte.  Size values support an optional suffix: k (Kibibyte),
M (Mebibyte), G (Gibibyte).

=item DSN

See L<"DSN (DATA SOURCE NAME) SPECIFICATIONS">.

=item Hash, hash, Array, array

Hash, hash, Array, and array values are comma-separated lists of values.
For example, C<--ignore-tables foo,bar> ignores tables C<foo> and C<bar>.

=back

=head1 CONFIGURATION FILES

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.

=head2 SYNTAX

The syntax of the configuration files is as follows:

=over

=item *

Whitespace followed by a hash sign (#) signifies that the rest of the line is a
comment.  This is deleted.  For example:

=item *

Whitespace is stripped from the beginning and end of all lines.

=item *

Empty lines are ignored.

=item *

Each line is permitted to be in either of the following formats:

  option
  option=value

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

=item *

Only long options are recognized.

=item *

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.

=back

=head2 EXAMPLE

This config file for pt-stalk,

  # Config for pt-stalk
  variable=Threads_connected
  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 C<--> are passed literally to mysql and mysqladmin.

=head2 READ ORDER

The tools read several configuration files in order:

=over

=item 1.

The global Percona Toolkit configuration file,
F</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.

=item 2.

The global tool-specific configuration file, F</etc/percona-toolkit/TOOL.conf>,
where C<TOOL> is a tool name like C<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.

=item 3.

The user's own Percona Toolkit configuration file,
F<$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.

=item 4.

The user's tool-specific configuration file, F<$HOME/.TOOL.conf>,
where C<TOOL> is a tool name like C<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.

=back

=head2 SPECIFYING

There is a special C<--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<first> 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 C<--config=/path/to/file>;
you must specify the option and the path to the file separated by whitespace
I<without an equal sign> between them, like:

  --config /path/to/file

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

=head1 DSN (DATA SOURCE NAME) SPECIFICATIONS

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 C<key=value> parts, like:

  h=host1,P=3306,u=bob

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
C<--host>, C<--user>, and C<--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 C<h=host1> and option C<--port=12345> are
specified, then the tool automatically adds C<P=12345> to DSN.

=head2 ESCAPING VALUES

DSNs are usually specified on the command line, so shell quoting and escaping
must be taken into account.  Special characters, like asterisk (C<*>), 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 (C<\>).  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 C<my,name>,
it must be specified as C<my\\,name> on most shells.  This applies to DSNs
and DSN-related options like C<--user>.

=head2 KEY PARTS

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:

=over

=item A

Default character set for the connection (C<SET NAMES>).

Enables character set settings in Perl and MySQL.  If the value is C<utf8>,
sets Perl's binmode on STDOUT to utf8, passes the C<mysql_enable_utf8> option
to DBD::mysql, and runs C<SET NAMES 'utf8'> after connecting to MySQL.  Other
values set binmode on STDOUT without the utf8 layer and run C<SET NAMES> after
connecting to MySQL.

Unfortunately, there is no way from within Perl itself to specify the client
library's character set.  C<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.

=item D

Default database to use when connecting.  Tools may C<USE> a different
databases while running.

=item F

Defaults file for the MySQL client library (the C client library used by
DBD::mysql, I<not Percona Toolkit itself>).  All tools all read the
C<[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 C</etc/mysql/my.cnf> then
C<~/.my.cnf>.  If you place the following in C<~/.my.cnf>, you won't have
to specify your MySQL username and password on the command line:

  [client]
  user=your_user_name
  pass=secret

Omitting the F part is usually the right thing to do.  As long as you have
configured your C<~/.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
L<"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.

=item h

MySQL hostname or IP address to connect to.

=item 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 L<https://dev.mysql.com/doc/refman/5.0/en/load-data-local.html>
and L<http://search.cpan.org/~capttofu/DBD-mysql/lib/DBD/mysql.pm>.
This option does exactly that.

=item p

MySQL password to use when connecting.

=item P

Port number to use for the connection.  Note that the usual special-case
behaviors apply: if you specify C<localhost> as your hostname on Unix systems,
the connection actually uses a socket file, not a TCP/IP connection, and thus
ignores the port.

=item S

MySQL socket file to use for the connection (on Unix systems).

=item u

MySQL username to use when connecting, if not current system user.

=back

=head2 BAREWORD

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

=head2 PROPAGATION

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.

=head1 ENVIRONMENT

The environment variable C<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.

=head1 SYSTEM REQUIREMENTS

Most tools require:

=over

=item * Perl v5.8 or newer

=item * Bash v3 or newer

=item * Core Perl modules like Time::HiRes

=back

Tools that connect to MySQL require:

=over

=item * Perl modules DBI and DBD::mysql

=item * MySQL 5.0 or newer

=back

Percona Toolkit officially supports and is tested on many popular Linux
distributions and MySQL 5.0 through 5.6; see http://goo.gl/srHm7 for the
list of supported platforms and versions.

=head1 BUGS

Please report bugs at L<https://jira.percona.com>.
Include the following information in your bug report:

=over

=item * Complete command-line used to run the tool

=item * Tool C<--version>

=item * MySQL version of all servers involved

=item * Output from the tool including STDERR

=item * Input files (log/dump/config files, etc.)

=back

If possible, include debugging output by running the tool with C<PTDEBUG>;
see L<"ENVIRONMENT">.

=head1 AUTHORS

=over

=item Baron Schwartz

Baron created Maatkit, from which Percona Toolkit was forked.  Many of
the tools and modules were originally written by Baron.

=item Daniel Nichter

Daniel has been the project's lead developer since 2008 until 2016.

=item Frank Cizmich

Frank was a full-time Percona Toolkit developer employed by Percona until 2016.

=item Carlos Salguero

Carlos has been the project's lead developer since 2016. He is hired by Percona.

=item Others

Many people have contributed code over the years.  See each tool's
"AUTHORS" section for details.

=back

=head1 COPYRIGHT, LICENSE, AND WARRANTY

Percona Toolkit is copyright 2011-2018 Percona LLC and/or its affiliates, et al.
See each program's documentation for complete copyright notices.

THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTABILITY 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.

=head1 VERSION

Percona Toolkit v3.1.0 released 2019-09-07

=cut
