pt-config-diff - Diff MySQL configuration files and server variables.
pt-config-diff [OPTIONS] CONFIG CONFIG [CONFIG...]
pt-config-diff diffs MySQL configuration files and server variables. CONFIG can be a filename or a DSN. At least two CONFIG sources must be given. Like standard Unix diff, there is no output if there are no differences.
Diff host1 config from SHOW VARIABLES against host2:
pt-config-diff h=host1 h=host2
Diff config from [mysqld] section in my.cnf against host1 config:
pt-config-diff /etc/my.cnf h=host1
Diff the [mysqld] section of two option files:
pt-config-diff /etc/my-small.cnf /etc/my-large.cnf
Percona Toolkit is mature, proven in the real world, and well tested, but all database tools can pose a risk to the system and the database server. Before using this tool, please:
Read the tool’s documentation
Review the tool’s known “BUGS”
Test the tool on a non-production server
Backup your production server and verify the backups
pt-config-diff diffs MySQL configurations by examining the values of server
system variables from two or more CONFIG sources specified on the command
line. A CONFIG source can be a DSN or a filename containing the output of
mysqld --help --verbose,
SHOW VARIABLES, or
an option file (e.g. my.cnf).
For each DSN CONFIG, pt-config-diff connects to MySQL and gets variables
and values by executing
SHOW /*!40103 GLOBAL*/ VARIABLES. This is
an “active config” because it shows what server values MySQL is
actively (currently) running with.
Only variables that all CONFIG sources have are compared because if a variable is not present then we cannot know or safely guess its value. For example, if you compare an option file (e.g. my.cnf) to an active config (i.e. SHOW VARIABLES from a DSN CONFIG), the option file will probably only have a few variables, whereas the active config has every variable. Only values of the variables present in both configs are compared.
Option file and DSN configs provide the best results.
There is no output when there are no differences. When there are differences, pt-config-diff prints a report to STDOUT that looks similar to the following:
2 config differences Variable my.master.cnf my.slave.cnf ========================= =============== =============== datadir /tmp/12345/data /tmp/12346/data port 12345 12346
Comparing MySQL variables is difficult because there are many variations and subtleties across the many versions and distributions of MySQL. When a comparison fails, the tool prints a warning to STDERR, such as the following:
Comparing log_error values (mysqld.log, /tmp/12345/data/mysqld.log) caused an error: Argument "/tmp/12345/data/mysqld.log" isn't numeric in numeric eq (==) at ./pt-config-diff line 2311.
Please report these warnings so the comparison functions can be improved.
pt-config-diff exits with a zero exit status when there are no differences, and 1 if there are.
This tool accepts additional command-line arguments. Refer to the “SYNOPSIS” and usage information for details.
Prompt for a password when connecting to MySQL.
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.
Read this comma-separated list of config files; if specified, this must be the first option on the command line. (This option does not specify a CONFIG; it’s equivalent to
short form: -D; type: string
Connect to this database.
short form: -F; type: string
Only read mysql options from the given file. You must give an absolute pathname.
Show help and exit.
short form: -h; type: string
Connect to host.
Compare the variables case-insensitively.
Ignore, do not compare, these variables.
short form: -p; type: string
Password to use for connection.
Create the given PID file. The tool won’t start if the PID file already exists and the PID it contains is different than the current PID. However, if the PID file exists and the PID it contains is no longer running, the tool will overwrite the PID file with the current PID. The PID file is removed automatically when the tool exits.
short form: -P; type: int
Port number to use for connection.
Print the MySQL config diff report to STDOUT. If you just want to check if the given configs are different or not by examining the tool’s exit status, then specify
--no-reportto suppress the report.
type: int; default: 78
Truncate report lines to this many characters. Since some variable values can be long, or when comparing multiple configs, it may help to increase the report width so values are not truncated beyond readability.
Set the MySQL variables in this comma-separated list of
By default, the tool sets:
Variables specified on the command line override these defaults. For example, specifying
--set-vars wait_timeout=500overrides the defaultvalue of
The tool prints a warning and continues if a variable cannot be set.
short form: -S; type: string
Socket file to use for connection.
short form: -u; type: string
MySQL user if not current user.
Show version and exit.
Check for the latest version of Percona Toolkit, MySQL, and other programs.
This is a standard “check for updates automatically” feature, with two additional features. First, the tool checks its own version and also the versions of the following software: operating system, Percona Monitoring and Management (PMM), MySQL, Perl, MySQL driver for Perl (DBD::mysql), and Percona Toolkit. Second, it checks for and warns about versions with known problems. For example, MySQL 5.5.25 had a critical bug and was re-released as 5.5.25a.
A secure connection to Percona’s Version Check database server is done to perform these checks. Each request is logged by the server, including software version numbers and unique ID of the checked system. The ID is generated by the Percona Toolkit installation script or when the Version Check database call is done for the first time.
Any updates or known problems are printed to STDOUT before the tool’s normal output. This feature should never interfere with the normal operation of the tool.
For more information, visit https://www.percona.com/doc/percona-toolkit/LATEST/version-check.html.
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
if the value contains whitespace it must be quoted. DSN options are
comma-separated. See the percona-toolkit manpage for full details.
dsn: charset; copy: yes
Default character set.
dsn: database; copy: yes
dsn: mysql_read_default_file; copy: yes
Only read default options from the given file
dsn: host; copy: yes
Connect to host.
dsn: password; copy: yes
Password to use when connecting. If password contains commas they must be escaped with a backslash: “exam,ple”
dsn: port; copy: yes
Port number to use for connection.
dsn: mysql_socket; copy: yes
Socket file to use for connection.
dsn: user; copy: yes
User for login if not current user.
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-config-diff ... > FILE 2>&1
Be careful: debugging output is voluminous and can generate several megabytes of output.
Using <PTDEBUG> might expose passwords. When debug is enabled, all command line parameters are shown in the output.
You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any reasonably new version of Perl.
For a list of known bugs, see https://jira.percona.com/projects/PT/issues.
Please report bugs at https://jira.percona.com/projects/PT. Include the following information in your bug report:
Complete command-line used to run the tool
MySQL version of all servers involved
Output from the tool including STDERR
Input files (log/dump/config files, etc.)
If possible, include debugging output by running the tool with
Visit http://www.percona.com/software/percona-toolkit/ to download the latest release of Percona Toolkit. Or, get the latest release from the command line:
wget percona.com/get/percona-toolkit.tar.gz wget percona.com/get/percona-toolkit.rpm wget percona.com/get/percona-toolkit.deb
You can also get individual tools from the latest release:
TOOL with the name of any tool.
ABOUT PERCONA TOOLKIT¶
This tool is part of Percona Toolkit, a collection of advanced command-line tools for MySQL developed by Percona. Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa. Those projects were created by Baron Schwartz and primarily developed by him and Daniel Nichter. Visit http://www.percona.com/software/ to learn about other free, open-source software from Percona.
COPYRIGHT, LICENSE, AND WARRANTY¶
This program is copyright 2011-2021 Percona LLC and/or its affiliates.
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.