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You can use the mysqld options and system variables that are described in this section to affect the operation of the binary log as well as to control which statements are written to the binary log. Startup options used with binary logging. The following list describes startup options for enabling and configuring the binary log. System variables used with binary logging are discussed later in this section.
Specify the maximum size of a row-based binary log event, in bytes. Rows are grouped into events smaller than this size if possible. The value should be a multiple of The default is The server logs all statements that change data to the binary log, which is used for backup and replication. The option value, if given, is the basename for the log sequence. The server creates binary log files in sequence by adding a numeric suffix to the basename.
This is a known issue; see Bug for more information. The index file for binary log file names. If no argument is given, the option sets the variable to 1. The options in the following list affect which statements are written to the binary log, and thus sent by a replication master server to its slaves.
There are also options for slave servers that control which statements received from the master should be executed or ignored. This option affects binary logging in a manner similar to the way that --replicate-do-db affects replication. The effects of this option depend on whether the statement-based or row-based logging format is in use, in the same way that the effects of --replicate-do-db depend on whether statement-based or row-based replication is in use.
To specify multiple databases you must use multiple instances of this option. Because database names can contain commas, the list will be treated as the name of a single database if you supply a comma-separated list.
An example of what does not work as you might expect when using statement-based logging: It is also faster to check only the default database rather than all databases if there is no need. Another case which may not be self-evident occurs when a given database is replicated even though it was not specified when setting the option.
Another important difference in --binlog-do-db handling for statement-based logging as opposed to the row-based logging occurs with regard to statements that refer to multiple databases. If you are using statement-based logging, the updates to both tables are written to the binary log.
However, when using the row-based format, only the changes to table1 are logged; table2 is in a different database, so it is not changed by the UPDATE. However, when using row-based logging, the change to table1 is logged, but not that to table2 —in other words, only changes to tables in the database named by --binlog-do-db are logged, and the choice of default database has no effect on this behavior.
This option affects binary logging in a manner similar to the way that --replicate-ignore-db affects replication. The effects of this option depend on whether the statement-based or row-based logging format is in use, in the same way that the effects of --replicate-ignore-db depend on whether statement-based or row-based replication is in use. The current database has no effect. When using statement-based logging, the following example does not work as you might expect.
Because the sales database was specified explicitly in the statement, the statement has not been filtered. However, when using row-based logging, the UPDATE statement's effects are not written to the binary log, which means that no changes to the sales.
To specify more than one database to ignore, use this option multiple times, once for each database. You should not use this option if you are using cross-database updates and you do not want these updates to be logged. Testing and debugging options. The following binary log options are used in replication testing and debugging.
They are not intended for use in normal operations. This option is used internally by the MySQL test suite for replication testing and debugging. System variables used with the binary log. The following list describes system variables for controlling binary logging.
They can be set at server startup and some of them can be changed at runtime using SET. Server options used to control binary logging are listed earlier in this section. The size of the cache to hold changes to the binary log during a transaction. A binary log cache is allocated for each client if the server supports any transactional storage engines and if the server has the binary log enabled --log-bin option. If you often use large transactions, you can increase this cache size to get better performance.
Begining with MySQL 5. Due to concurrency issues, a slave can become inconsistent when a transaction contains updates to both transactional and non-transactional tables. MySQL tries to preserve causality among these statements by writing non-transactional statements to the transaction cache, which is flushed upon commit. However, problems arise when modifications done to nontransactional tables on behalf of a transaction become immediately visible to other connections because these changes may not be written immediately into the binary log.
Beginning with MySQL 5. By default, this variable is disabled. Otherwise, such statements are likely to cause the slave to diverge from the master. The rules governing when changes to this variable take effect and how long the effect lasts are the same as for other MySQL server system variables.
When MIXED is specified, statement-based replication is used, except for cases where only row-based replication is guaranteed to lead to proper results. An exception to this rule is that MIXED always uses statement-based replication for stored functions and triggers.
There are exceptions when you cannot switch the replication format at runtime:. If the session is currently in row-based replication mode and has open temporary tables. These effects are discussed in detail in the descriptions of the individual options. The minimum value is The maximum and default values are 4GB on bit platforms and 16PB petabytes on bit platforms.
If nontransaction statements within a transaction require more than this many bytes of memory, the server generates an error. If a write to the binary log causes the current log file size to exceed the value of this variable, the server rotates the binary logs closes the current file and opens the next one. The minimum value is bytes. The maximum and default value is 1GB. A transaction is written in one chunk to the binary log, so it is never split between several binary logs.
If you often use large nontransactional statements during transactions, you can increase this cache size to get more performance. There is one write to the binary log per statement if autocommit is enabled, and one write per transaction otherwise.
A value of 1 is the safest choice because in the event of a crash you lose at most one statement or transaction from the binary log. However, it is also the slowest choice unless the disk has a battery-backed cache, which makes synchronization very fast.
Binary Log Options and Variables. From within a stored function or a trigger. Common Replication Administration Tasks.