mydumper/README.md
2019-08-09 13:38:00 +02:00

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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](https://github.com/maxbube/mydumper/releases) then:
### RedHat / Centos
```bash
yum install https://github.com/maxbube/mydumper/releases/download/v0.9.5/mydumper-0.9.5-1.el7.x86_64.rpm
```
### Ubuntu / Debian
```bash
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
```
## How to build it?
Run:
```bash
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
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:
```bash
mydumper --regex '^(?!(mysql\.|test\.))'
```
To dump only mysql and test databases:
```bash
mydumper --regex '^(mysql\.|test\.)'
```
To not dump all databases starting with test:
```bash
mydumper --regex '^(?!(test))'
```
Of course, regex functionality can be used to describe pretty much any list of tables.