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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 install mydumper/myloader?

First get the correct url from the releases section then:

RedHat / Centos

yum install https://github.com/maxbube/mydumper/releases/download/v0.9.5/mydumper-0.9.5-1.el7.x86_64.rpm

Ubuntu / Debian

wget https://github.com/maxbube/mydumper/releases/download/v0.9.5/mydumper_0.9.5-1.xenial_amd64.deb
dpkg -i mydumper_0.9.5-1.xenial_amd64.deb

OSX

By using Homebrew

brew install mydumper

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: brew install glib mysql-client pcre pkgconfig cmake openssl gettext libffi gdbm readline xz python sqlite

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

To build against mysql libs < 5.7 you need to disable SSL adding -DWITH_SSL=OFF

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\.))'

To dump only mysql and test databases:

 mydumper --regex '^(mysql\.|test\.)'

To not dump all databases starting with test:

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

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