- NAME
- SYNOPSIS
- RISKS
- DESCRIPTION
- PRIVILEGES
- OUTPUT
- OPTIONS
- DSN OPTIONS
- DOWNLOADING
- ENVIRONMENT
- SYSTEM REQUIREMENTS
- BUGS
- COPYRIGHT, LICENSE AND WARRANTY
- AUTHOR
- ABOUT MAATKIT
- VERSION
Maatkit has become part of Percona Toolkit, and there will be no further development or releases of Maatkit separately from Percona Toolkit.
mk-slave-delay - Make a MySQL slave server lag behind its master.
Usage: mk-slave-delay [OPTION...] SLAVE-HOST [MASTER-HOST]
mk-slave-delay starts and stops a slave server as needed to make it lag behind the master. The SLAVE-HOST and MASTER-HOST use DSN syntax, and values are copied from the SLAVE-HOST to the MASTER-HOST if omitted.
To hold slavehost one minute behind its master for ten minutes:
mk-slave-delay --delay 1m --interval 15s --run-time 10m slavehost
The following section is included to inform users about the potential risks, whether known or unknown, of using this tool. The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs.
mk-slave-delay is generally very low-risk. It simply starts and stops the replication SQL thread. This might cause monitoring systems to think the slave is having trouble.
At the time of this release, we know of no bugs that could cause serious harm to users.
The authoritative source for updated information is always the online issue tracking system. Issues that affect this tool will be marked as such. You can see a list of such issues at the following URL: http://www.maatkit.org/bugs/mk-slave-delay.
See also BUGS for more information on filing bugs and getting help.
mk-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, mk-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, mk-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-HOST and optional MASTER-HOST are both DSNs. See DSN OPTIONS.
Missing MASTER-HOST values are filled in with values from SLAVE-HOST, so you
don't need to specify them in both places. mk-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.
mk-slave-delay tries to exit gracefully by trapping signals such as Ctrl-C.
You cannot bypass --[no]continue with a trappable signal.
mk-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
mk-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.
Prompt for a password when connecting to MySQL.
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.
type: Array
Read this comma-separated list of config files; if specified, this must be the first option on the command line.
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
mk-slave-delay with Control-C.
Fork to the background and detach from the shell. POSIX operating systems only.
short form: -F; type: string
Only read mysql options from the given file. You must give an absolute pathname.
type: time; default: 1h
How far the slave should lag its master.
Show help and exit.
short form: -h; type: string
Connect to host.
type: time; default: 1m
How frequently mk-slave-delay should check whether the slave needs to be
started or stopped.
type: string
Print all output to this file when daemonized.
short form: -p; type: string
Password to use when connecting.
type: string
Create the given PID file when daemonized. The file contains the process ID of the daemonized instance. The PID file is removed when the daemonized instance exits. The program checks for the existence of the PID file when starting; if it exists and the process with the matching PID exists, the program exits.
short form: -P; type: int
Port number to use for connection.
short form: -q
Don't print informational messages about operation. See OUTPUT for details.
type: time
How long mk-slave-delay should run before exiting. The default is to run
forever.
type: string; default: wait_timeout=10000
Set these MySQL variables. Immediately after connecting to MySQL, this string will be appended to SET and executed.
short form: -S; type: string
Socket file to use for connection.
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-HOST on the command
line, mk-slave-delay examines the slave's SHOW SLAVE STATUS to determine the
hostname and port for connecting to the master.
mk-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-HOST option
explicitly on the command line.
short form: -u; type: string
User for login if not current user.
Show version and exit.
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 maatkit 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.
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.
You can download Maatkit from Google Code at http://code.google.com/p/maatkit/, or you can get any of the tools easily with a command like the following:
wget http://www.maatkit.org/get/toolname or wget http://www.maatkit.org/trunk/toolname
Where toolname can be replaced with the name (or fragment of a name) of any
of the Maatkit tools. Once downloaded, they're ready to run; no installation is
needed. The first URL gets the latest released version of the tool, and the
second gets the latest trunk code from Subversion.
The environment variable MKDEBUG enables verbose debugging output in all of
the Maatkit tools:
MKDEBUG=1 mk-....
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.maatkit.org/bugs/mk-slave-delay.
Please use Google Code Issues and Groups to report bugs or request support: http://code.google.com/p/maatkit/. You can also join #maatkit on Freenode to discuss Maatkit.
Please include the complete command-line used to reproduce the problem you are
seeing, the version of all MySQL servers involved, the complete output of the
tool when run with --version, and if possible, debugging output produced by
running with the MKDEBUG=1 environment variable.
This program is copyright 2007-2011 Sergey Zhuravlev and Baron Schwartz. Feedback and improvements are welcome.
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.
Sergey Zhuravlev, Baron Schwartz
This tool is part of Maatkit, a toolkit for power users of MySQL. Maatkit was created by Baron Schwartz; Baron and Daniel Nichter are the primary code contributors. Both are employed by Percona. Financial support for Maatkit development is primarily provided by Percona and its clients.
This manual page documents Ver 1.0.23 Distrib 7540 $Revision: 7477 $.