| PT-SLAVE-DELAY(1p) | User Contributed Perl Documentation | PT-SLAVE-DELAY(1p) |
pt-slave-delay - Make a MySQL slave server lag behind its master.
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
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:
"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.
pt-slave-delay requires the following privileges: PROCESS, REPLICATION CLIENT, and SUPER.
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.
This tool accepts additional command-line arguments. Refer to the "SYNOPSIS" and usage information for details.
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.
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.
The database to use for the connection.
Only read mysql options from the given file. You must give an absolute pathname.
How far the slave should lag its master.
Connect to host.
How frequently "pt-slave-delay" should check whether the slave needs to be started or stopped.
Print all output to this file when daemonized.
Password to use when connecting. If password contains commas they must be escaped with a backslash: "exam\,ple"
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 number to use for connection.
Don't print informational messages about operation. See OUTPUT for details.
How long "pt-slave-delay" should run before exiting. The default is to run forever.
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 file to use for connection.
"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 for login if not current user.
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>.
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
Default database.
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. If password contains commas they must be escaped with a backslash: "exam\,ple"
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-slave-delay ... > 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-slave-delay>.
Please report bugs at <https://jira.percona.com/projects/PT>. 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:
wget percona.com/get/TOOL
Replace "TOOL" with the name of any tool.
Sergey Zhuravlev and Baron Schwartz
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.
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.
pt-slave-delay 3.0.13
Hey! The above document had some coding errors, which are explained below:
| 2019-02-03 | perl v5.28.1 |