pt-slave-delay(1p)
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 2011-2016 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 2.2.20
Opportunity
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
Free Books
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Education
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.
