Provided by: percona-toolkit_2.2.16-1_all 
NAME
pt-slave-delay - Make a MySQL slave server lag behind its master.
SYNOPSIS
Usage: pt-slave-delay [OPTIONS] SLAVE_DSN [MASTER_DSN]
pt-slave-delay starts and stops a slave server as needed to make it lag behind the master.
The SLAVE_DSN and MASTER_DSN use DSN syntax, and values are copied from the SLAVE_DSN to
the MASTER_DSN if omitted.
To hold slavehost one minute behind its master for ten minutes:
pt-slave-delay --delay 1m --interval 15s --run-time 10m slavehost
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-slave-delay" watches a slave and starts and stops its replication SQL thread as
necessary to hold it at least as far behind the master as you request. In practice, it
will typically cause the slave to lag between "--delay" and "--delay"+"--interval" behind
the master.
It bases the delay on binlog positions in the slave's relay logs by default, so there is
no need to connect to the master. This works well if the IO thread doesn't lag the master
much, which is typical in most replication setups; the IO thread lag is usually
milliseconds on a fast network. If your IO thread's lag is too large for your purposes,
"pt-slave-delay" can also connect to the master for information about binlog positions.
If the slave's I/O thread reports that it is waiting for the SQL thread to free some relay
log space, "pt-slave-delay" will automatically connect to the master to find binary log
positions. If "--ask-pass" and "--daemonize" are given, it is possible that this could
cause it to ask for a password while daemonized. In this case, it exits. Therefore, if
you think your slave might encounter this condition, you should be sure to either specify
"--use-master" explicitly when daemonizing, or don't specify "--ask-pass".
The SLAVE_DSN and optional MASTER_DSN are both DSNs. See "DSN OPTIONS". Missing
MASTER_DSN values are filled in with values from SLAVE_DSN, so you don't need to specify
them in both places. "pt-slave-delay" reads all normal MySQL option files, such as
~/.my.cnf, so you may not need to specify username, password and other common options at
all.
"pt-slave-delay" tries to exit gracefully by trapping signals such as Ctrl-C. You cannot
bypass "--[no]continue" with a trappable signal.
PRIVILEGES
pt-slave-delay requires the following privileges: PROCESS, REPLICATION CLIENT, and SUPER.
OUTPUT
If you specify "--quiet", there is no output. Otherwise, the normal output is a status
message consisting of a timestamp and information about what "pt-slave-delay" is doing:
starting the slave, stopping the slave, or just observing.
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.
--[no]continue
default: yes
Continue replication normally on exit. After exiting, restart the slave's SQL thread
with no UNTIL condition, so it will run as usual and catch up to the master. This is
enabled by default and works even if you terminate "pt-slave-delay" with Control-C.
--daemonize
Fork to the background and detach from the shell. POSIX operating systems only.
--database
short form: -D; type: string
The database to use for the connection.
--defaults-file
short form: -F; type: string
Only read mysql options from the given file. You must give an absolute pathname.
--delay
type: time; default: 1h
How far the slave should lag its master.
--help
Show help and exit.
--host
short form: -h; type: string
Connect to host.
--interval
type: time; default: 1m
How frequently "pt-slave-delay" should check whether the slave needs to be started or
stopped.
--log
type: string
Print all output to this file when daemonized.
--password
short form: -p; type: string
Password to use when connecting. If password contains commas they must be escaped
with a backslash: "exam\,ple"
--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.
--quiet
short form: -q
Don't print informational messages about operation. See OUTPUT for details.
--run-time
type: time
How long "pt-slave-delay" should run before exiting. The default is to run forever.
--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.
--use-master
Get binlog positions from master, not slave. Don't trust the binlog positions in the
slave's relay log. Connect to the master and get binlog positions instead. If you
specify this option without giving a MASTER_DSN on the command line, "pt-slave-delay"
examines the slave's SHOW SLAVE STATUS to determine the hostname and port for
connecting to the master.
"pt-slave-delay" uses only the MASTER_HOST and MASTER_PORT values from SHOW SLAVE
STATUS for the master connection. It does not use the MASTER_USER value. If you want
to specify a different username for the master than the one you use to connect to the
slave, you should specify the MASTER_DSN option explicitly on the command line.
--user
short form: -u; type: string
User for login 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-slave-delay ... > 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.
BUGS
For a list of known bugs, see <http://www.percona.com/bugs/pt-slave-delay>.
Please report bugs at <https://bugs.launchpad.net/percona-toolkit>. Include the following
information in your bug report:
• Complete command-line used to run the tool
• Tool "--version"
• 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 "PTDEBUG"; see
"ENVIRONMENT".
DOWNLOADING
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:
wget percona.com/get/TOOL
Replace "TOOL" with the name of any tool.
AUTHORS
Sergey Zhuravlev and Baron Schwartz
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 2011-2015 Percona LLC and/or its affiliates, 2007-2011 Sergey
Zhuravle and Baron Schwartz.
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.
VERSION
pt-slave-delay 2.2.16