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server’s binlog_transaction_compression  system variable is set to ON , transaction payloads are compressed and then written to the server’s binary log file as a single event (a Transaction_payload_event ). With the --verbose  option, mysqlbinlog  adds comments stating the compression algorithm used, the compressed payload size that was originally received, and the resulting payload size after decompression. 

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## Note 

The end position ( end_log_pos ) that mysqlbinlog  states for an individual event that was part of a compressed transaction payload is the same as the end position of the original compressed payload. Multiple decompressed events can therefore have the same end position. 

mysqlbinlog ’s own connection compression does less if transaction payloads are already compressed, but still operates on uncompressed transactions and headers. 

For more information on binary log transaction compression, see Section 5.4.4.5, “Binary Log Transaction Compression” . 

When running mysqlbinlog  against a large binary log, be careful that the filesystem has enough space for the resulting files. To configure the directory that mysqlbinlog  uses for temporary files, use the TMPDIR  environment variable. 

mysqlbinlog  sets the value of pseudo_slave_mode  to true before executing any SQL statements. This system variable affects the handling of XA transactions, the original_commit_timestamp  replication delay timestamp and the original_server_version  system variable, and unsupported SQL modes. 

mysqlbinlog  supports the following options, which can be specified on the command line or in the [mysqlbinlog]  and [client]  groups of an option file. For information about option files used by MySQL programs, see Section 4.2.2.2, “Using Option Files” . 

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