Introduction

Replication state on the slave is stored in two files: relay-log.info and master.info. The slave SQL thread commits transactions to a storage engine and then updates these files to indicate the next event from the relay log to be executed. When the slave mysqld process is stopped between the commit and the file update, replication state is inconsistent and the slave SQL thread will duplicate the last transaction when the slave mysqld process is restarted.

Details

This feature prevents that for the InnoDB storage engine by storing replication state in the InnoDB transaction log. On restart, this state is used to make the replication state files consistent with InnoDB.

The feature is enabled by the configuration parameter rpl_transaction_enabled=1. Normally, this is added to the mysqld section in /etc/my.cnf.

The state stored in the InnoDB transaction log can be cleared setting a parameter and then committing a transaction in InnoDB. For example:

set session innodb_clear_replication_status=1;
create table foo(i int) type=InnoDB;
insert into foo values (1);
commit;
drop table foo;

TODO -- describe reset slave purge binlog