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This page contains the configuration and implementation details for Drizzle replication.
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See these pages for user-level information:
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The replication slave plugin provides a native implementation of replication
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between two Drizzle processes.
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This plugin requires a master that is running with the InnoDB replication log
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Replication enables data from one Drizzle database server (the master) to be replicated to one or more Drizzle database servers (the slaves). It provides a native implementation of replication between two Drizzle processes. Depending on your configuration, you can replicate all databases, selected databases, or selected tables within a database.
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Drizzle’s replication system is entirely new and different from MySQL. Replication events are stored using Google Protocol Buffer messages in an InnoDB table. These events are read by the slave, stored locally, and applied. The advantage of the Google Protocol Buffer messages is a script or program can be put together in pretty much any language in minutes, and read the replication log. In other words, replication plugins are easy to implement, which enable developers to entirely customize their replication system.
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This plugin requires a master that is running with the InnoDB replication log enabled. The slave plugin allows a server to replicate from another server that is using the innodb-trx log. It is a very simple setup:
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master options: –innodb.replication-log=true
slave options: –plugin-add=slave –slave.config-file=XYZ
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The config file may contain the following options in option=value format:
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master-host – hostname/ip of the master host
master-port – port used by the master server
master-user – username
master-pass – password
max-reconnects – max # of reconnect attempts if the master disappears
seconds-between-reconnects – how long to wait between reconnect attempts
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Most of the options that can be used to control the replication slave plugin
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can only be given in a configuration file. The only exception is the
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**config-file** option which designates the location of this configuration
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Path to the replication slave configuration file.
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can only be given in a configuration file. The only exceptions are the
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:option:`--slave.config-file` and :option:`--slave.max-commit-id` options.
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.. option:: --slave.config-file=arg
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Path to the replication slave configuration file. By default, the
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plugin will look for a file named `slave.cfg` in the `etc` directory
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of the Drizzle installation. If you want to specify a different path or
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configuration file name, it is best to specify a full path to the
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file. The relative path used by plugins is within the :option:`--datadir`
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directory, so a full path is recommended.
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.. option:: --slave.max-commit-id=arg
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Manually set the maximum commit ID the slave is assumed to have retrieved
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from the master. This value will be used by the slave to determine where
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to begin retrieving replication messages from the master transaction log.
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This option can be used to provision a new slave machine by setting it to
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the value output from the drizzledump client when used with the
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--single-transaction option.
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This value is not allowed to be set via the configuration file since
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you would normally only set it once on initial slave startup. This
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eliminates the possibility of forgetting to delete it from the configuration
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file for subsequent slave restarts.
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The options below are read from the configuration file.
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.. confval:: master-host
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Hostname/IP address of the master server.
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.. confval:: master-port
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Drizzle port used by the master server. Default is 3306.
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.. confval:: master-user
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Username to use for connecting to the master server.
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Password associated with the username given by **master-user**.
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.. confval:: master-pass
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Password associated with the username given by :confval:`master-user`.
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.. confval:: max-reconnects
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The number of reconnection attempts the slave plugin will try if the
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master server becomes unreachable. Default is 10.
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**seconds-between-reconnects**
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.. confval:: seconds-between-reconnects
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The number of seconds to wait between reconnect attempts when the master
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server becomes unreachable. Default is 30.
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.. confval:: io-thread-sleep
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The number of seconds the IO (producer) thread sleeps between queries to the
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master for more replication events. Default is 5.
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.. confval:: applier-thread-sleep
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The number of seconds the applier (consumer) thread sleeps between applying
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replication events from the local queue. Default is 5.
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Implementation Details
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----------------------
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metadata. It stores everything in the **sys_replication** schema. The
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following are the tables that it will create:
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**sys_replication.io_state**
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.. dbtable:: sys_replication.io_state
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Stores metadata about the IO/producer thread.
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**sys_replication.applier_state**
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.. dbtable:: sys_replication.applier_state
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Stores metadata about the applier/consumer thread.
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**sys_replication.queue**
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.. dbtable:: sys_replication.queue
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The replication event queue.
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plugin/slave/docs/index.rst
