pt-config-diffp - Online in the Cloud

PROGRAM:

NAME

pt-config-diff - Diff MySQL configuration files and server variables.

SYNOPSIS

Usage: 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

RISKS

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

DESCRIPTION

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.

OUTPUT

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.

EXIT STATUS

pt-config-diff exits with a zero exit status when there are no differences, and 1 if there
are.

OPTIONS

This tool accepts additional command-line arguments. Refer to the "SYNOPSIS" and usage
information for details.

--ask-pass
Prompt for a password when connecting to MySQL.

--charset
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. (This option does not specify a CONFIG; it's equivalent
to "--defaults-file".)

--database
short form: -D; type: string

Connect to this database.

--defaults-file
short form: -F; type: string

Only read mysql options from the given file. You must give an absolute pathname.

--help
Show help and exit.

--host
short form: -h; type: string

Connect to host.

--[no]ignore-case
default: yes

Compare the variables case-insensitively.

--ignore-variables
type: array

Ignore, do not compare, these variables.

--password
short form: -p; type: string

Password to use for connection.

--pid
type: string

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.

--port
short form: -P; type: int

Port number to use for connection.

--[no]report
default: yes

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.

--report-width
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-vars
type: Array

Set the MySQL variables in this comma-separated list of "variable=value" pairs.

By default, the tool sets:

wait_timeout=10000

Variables specified on the command line override these defaults. For example,
specifying "--set-vars wait_timeout=500" overrides the defaultvalue of 10000.

The tool prints a warning and continues if a variable cannot be set.

--socket
short form: -S; type: string

Socket file to use for connection.

--user
short form: -u; type: string

MySQL user if not current user.

--version
Show version and exit.

--[no]version-check
default: yes

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 the version of other programs on the local system in
addition to its own version. For example, it checks the version of every MySQL server
it connects to, Perl, and the Perl module DBD::mysql. 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.

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/version-check>.

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 percona-toolkit 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. If password contains commas they must be escaped
with a backslash: "exam\,ple"

· 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.

ENVIRONMENT

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.

SYSTEM REQUIREMENTS

You need Perl, DBI, DBD::mysql, and some core packages that ought to be installed in any
reasonably new version of Perl.

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