Provided by: percona-toolkit_3.1+dfsg-1.1_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 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>.
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://jira.percona.com/projects/PT>. 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 2011-2018 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 3.1.0
POD ERRORS
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