Output Files

mydumper generates several files during the generation of the dump. Many of these are for the table data itself since every table has at least one file.


When a dump is executed a file called metadata.partial is created in the output directory and is renamed to metadata when mydumper finish without error. This contains the start and end time of the dump as well as the master binary log positions if applicable.

This is an example of the content of this file:

Started dump at: 2011-05-05 13:57:17
  Log: linuxjedi-laptop-bin.000001
  Pos: 106

Finished dump at: 2011-05-05 13:57:17

Table Data

The data from every table is written into a separate file, also if the --rows option is used then each chunk of table will be in a separate file. The file names for this are in the format:


or if chunked:


Where ‘chunk’ is a number padded with up to 5 zeros.

Table Schemas

When the --schemas option is used mydumper will create a file for the schema of every table it is writing data for. The files for this are in the following format:


Binary Logs

Binary logs are retrieved when --binlogs option has been set. This will store them in the binlog_snapshot/ sub-directory inside the dump directory.

The binary log files have the same filename as the MySQL server that supplies them and will also have a .gz on the end if they are compressed.

Daemon mode

Daemon mode does things a little differently. There are the directories 0 and 1 inside the dump directory. These alternate when dumping so that if mydumper fails for any reason there is still a good snapshot. When a snapshot dump is complete the last_dump symlink is updated to point to that dump.

If binary logging is enabled mydumper will connect as if it is a slave server and constantly retreives the binary logs into the binlogs subdirectory.