pt-config-diff - Diff MySQL configuration files and server variables.
pt-config-diff [OPTION...] 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
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.
pt-config-diff reads MySQL’s configuration and examines it and is thus very low risk.
At the time of this release there are no known bugs that pose a serious risk.
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.percona.com/bugs/pt-config-diff.
See also “BUGS” for more information on filing bugs and getting help.
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, my_print_defaults, 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 --defaults-file.)
Fork to the background and detach from the shell. POSIX operating systems only.
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.
Ignore, do not compare, these variables.
short form: -p; type: string
Password to use for connection.
Create the given PID file when daemonized. The file contains the process ID of the daemonized instance. The PID file is removed when the daemonized instance exits. The program checks for the existence of the PID file when starting; if it exists and the process with the matching PID exists, the program 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-report to 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.
type: string; default: wait_timeout=10000
Set these MySQL variables. Immediately after connecting to MySQL, this string will be appended to SET and executed.
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.
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 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.
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.
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 http://www.percona.com/bugs/pt-config-diff.
Please report bugs at https://bugs.launchpad.net/percona-toolkit. Include the following information in your bug report:
If possible, include debugging output by running the tool with PTDEBUG; see “ENVIRONMENT”.
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:
Replace TOOL with the name of any tool.
This tool is part of Percona Toolkit, a collection of advanced command-line tools developed by Percona for MySQL support and consulting. Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa. Those projects were created by Baron Schwartz and developed primarily by him and Daniel Nichter, both of whom are employed by Percona. Visit http://www.percona.com/software/ for more software developed by Percona.
This program is copyright 2011-2012 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 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.
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