What is mydumper? Why?

• Parallelism (hence, speed) and performance (avoids expensive character set conversion routines, efficient code overall)
• Easier to manage output (separate files for tables, dump metadata, etc, easy to view/parse data)
• Consistency - maintains snapshot across all threads, provides accurate master and slave log positions, etc
• Manageability - supports PCRE for specifying database and tables inclusions and exclusions

How to build it?

Run:

cmake .
make

One needs to install development versions of required libaries (MySQL, GLib, ZLib, PCRE): NOTE: you must use the correspondent mysql devel package.

• Ubuntu or Debian: apt-get install libglib2.0-dev libmysqlclient15-dev zlib1g-dev libpcre3-dev libssl-dev
• Fedora, RedHat and CentOS: yum install glib2-devel mysql-devel zlib-devel pcre-devel openssl-devel
• openSUSE: zypper install glib2-devel libmysqlclient-devel pcre-devel zlib-devel
• MacOSX: port install glib2 mysql5 pcre pkgconfig cmake (You may want to run 'port select mysql mysql5' afterwards)

One has to make sure, that pkg-config, mysql_config, pcre-config are all in $PATH

Binlog dump is disabled by default to compile with it you need to add -DWITH_BINLOG=ON to cmake options

How does consistent snapshot work?

This is all done following best MySQL practices and traditions:

• As a precaution, slow running queries on the server either abort the dump, or get killed
• Global write lock is acquired ("FLUSH TABLES WITH READ LOCK")
• Various metadata is read ("SHOW SLAVE STATUS","SHOW MASTER STATUS")
• Other threads connect and establish snapshots ("START TRANSACTION WITH CONSISTENT SNAPSHOT") ** On pre-4.1.8 it creates dummy InnoDB table, and reads from it.
• Once all worker threads announce the snapshot establishment, master executes "UNLOCK TABLES" and starts queueing jobs.

This for now does not provide consistent snapshots for non-transactional engines - support for that is expected in 0.2 :)

How to exclude (or include) databases?

Once can use --regex functionality, for example not to dump mysql and test databases:

 mydumper --regex '^(?!(mysql|test))'

Of course, regex functionality can be used to describe pretty much any list of tables.