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What is MyDumper?

MyDumper is a MySQL Logical Backup Tool. It has 2 tools:

  • mydumper which is responsible to export a consistent backup of MySQL databases
  • myloader reads the backup from mydumper, connects the to destination database and imports the backup.

Both tools use multithreading capabilities.
MyDumper is Open Source and maintained by the community, it is not a Percona, MariaDB or MySQL product.

Why do we need MyDumper?

  • 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

release=$(curl -Ls -o /dev/null -w %{url_effective} https://github.com/mydumper/mydumper/releases/latest | cut -d'/' -f8)
yum install https://github.com/mydumper/mydumper/releases/download/${release}/mydumper-${release:1}.el7.x86_64.rpm
yum install https://github.com/mydumper/mydumper/releases/download/${release}/mydumper-${release:1}.el8.x86_64.rpm

Ubuntu / Debian

For ubuntu, you need to install the dependencies:

apt-get install libatomic1

Then you can download and install the package:

release=$(curl -Ls -o /dev/null -w %{url_effective} https://github.com/mydumper/mydumper/releases/latest | cut -d'/' -f8)
wget https://github.com/mydumper/mydumper/releases/download/${release}/mydumper_${release:1}.$(lsb_release -cs)_amd64.deb
dpkg -i mydumper_${release:1}.$(lsb_release -cs)_amd64.deb

FreeBSD

By using pkg

pkg install mydumper

or from ports

cd /usr/ports/databases/mydumper && make install

OSX

By using Homebrew

brew install mydumper

Dependencies for building mydumper

One needs to install development tools:

  • Ubuntu or Debian:
apt-get install cmake g++ git
  • Fedora, RedHat and CentOS:
yum install -y cmake gcc gcc-c++ git make
  • MacOSX:
brew install cmake pkg-config sphinx-doc glib mysql-client openssl@1.1 pcre
port install pkgconfig cmake

One needs to install development versions of GLib, ZLib, PCRE and ZSTD:

  • Ubuntu or Debian:
apt-get install libglib2.0-dev zlib1g-dev libpcre3-dev libssl-dev libzstd-dev
  • Fedora, RedHat and CentOS:
yum install -y glib2-devel openssl-devel pcre-devel zlib-devel libzstd-devel
  • openSUSE:
zypper install glib2-devel libmysqlclient-devel pcre-devel zlib-devel
  • MacOSX:
port install glib2 pcre 

One needs to install MySQL/Percona/MariaDB development versions:

  • Ubuntu or Debian:
apt-get install libmysqlclient-dev
apt-get install libperconaserverclient20-dev
apt-get install libmariadbclient-dev 
  • Fedora, RedHat and CentOS:
yum install -y mysql-devel
yum install -y Percona-Server-devel-57
yum install -y mariadb-devel

CentOS 7 comes by default with MariaDB 5.5 libraries which are very old. It might be better to download a newer version of these libraries (MariaDB, MySQL, Percona etc).

  • openSUSE:
zypper install libmysqlclient-devel
  • MacOSX: port install mysql5 (You may want to run 'port select mysql mysql5' afterwards)

How to build it?

Run:

cmake .
make

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

Build Docker image

You can build the Docker image either from local sources or directly from Github sources with the provided Dockerfile.

docker build --build-arg CMAKE_ARGS='-DWITH_ZSTD=ON' -t mydumper github.com/mydumper/mydumper

Keep in mind that the main purpose the Dockerfile addresses is development and build from source locally. It might not be optimal for distribution purposes, but can also work as a quick build and run solution with the above one-liner, though.

How to use mydumper

See Usage

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 read 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))'

To dump specify tables in different databases (Note: The name of tables should end with $. related issue):

 mydumper --regex '^(db1\.table1$|db2\.table2$)'

If you want to dump a couple of databases but discard some tables, you can do:

 mydumper --regex '^(?=(?:(db1\.|db2\.)))(?!(?:(db1\.table1$|db2\.table2$)))'

Which will dump all the tables in db1 and db2 but it will exclude db1.table1 and db2.table2

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

How to use --exec?

You can execute external commands with --exec like this:

 mydumper --exec "/usr/bin/gzip FILENAME"

--exec is single threaded, similar implementation than Stream. The exec program must be an absolute path. FILENAME will be replaced by the filename that you want to be processed. You can set FILENAME in any place as argument.

Defaults file

The default file (aka: --defaults-file parameter) is starting to be more important in MyDumper

  • mydumper and myloader sections:
[mydumper]
host = 127.0.0.1
user = root
password = p455w0rd
database = db
rows = 10000

[myloader]
host = 127.0.0.1
user = root
password = p455w0rd
database = new_db
innodb-optimize-keys = AFTER_IMPORT_PER_TABLE
  • Variables for mydumper and myloader executions:
[mydumper_variables]
wait_timeout = 300
sql_mode = ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION

[myloader_variables]
long_query_time = 300
innodb_flush_log_at_trx_commit = 0
  • Per table sections:
[`db`.`table`]
where = column > 20