Getting Started with MyRocks

Alex Yang edited this page Mar 16, 2017 · 12 revisions

Download Facebook MySQL 5.6

See Build Steps for directions on how to build from source.

Set up my.cnf

To enable RocksDB storage engine (a.k.a. MyRocks), you need to set at least the following parameters in my.cnf.

[mysqld]
rocksdb
default-storage-engine=rocksdb
skip-innodb
default-tmp-storage-engine=MyISAM
collation-server=latin1_bin #(or utf8_bin, binary)

log-bin
binlog-format=ROW

If you want to use both InnoDB and MyRocks within the same instance, set allow-multiple-engines and remove skip-innodb in my.cnf. Using mixed storage engines is not recommended in production, because it is not really transactional. But it is ok for experimental purposes.

Statement based binary logging is allowed on replication slave, but not on master. This is because MyRocks does not support next-key locking.

In addition you may want to set some of the following settings :

datadir=<location_for_data_files>
socket=<socket_file>
port=<port>
sql_mode=<mode1>[,<mode2>]

NOTE - this is not exhaustive list of settings by any means, see my.cnf tuning and server variables for more details.

Initialize database with mysql_install_db

mysql_install_db --defaults-file=/path/to/my.cnf

Start Mysqld

mysqld_safe --defaults-file=/path/to/my.cnf

Create a RocksDB table

    CREATE TABLE `linktable` (
      `id1` bigint(20) unsigned NOT NULL DEFAULT '0',
      `id1_type` int(10) unsigned NOT NULL DEFAULT '0',
      `id2` bigint(20) unsigned NOT NULL DEFAULT '0',
      `id2_type` int(10) unsigned NOT NULL DEFAULT '0',
      `link_type` bigint(20) unsigned NOT NULL DEFAULT '0',
      `visibility` tinyint(3) NOT NULL DEFAULT '0',
      `data` varchar(255) NOT NULL DEFAULT '',
      `time` bigint(20) unsigned NOT NULL DEFAULT '0',
      `version` int(11) unsigned NOT NULL DEFAULT '0',
      PRIMARY KEY (link_type, `id1`,`id2`) COMMENT 'cf_link_pk',
      KEY `id1_type` (`id1`,`link_type`,`visibility`,`time`,`version`,`data`) COMMENT 'rev:cf_link_id1_type'
    ) ENGINE=RocksDB DEFAULT COLLATE=latin1_bin; 

The example highlights some important features and limitations in MyRocks. For more on limitations, please read MyRocks Limitations.

Interpretation of COMMENT associated with key definitions

  • MyRocks data is stored in RocksDB, per index basis. RocksDB internally allocates a column family to store indexes. By default all data is stored into the default column family. You can change the column family by setting the COMMENT for a given index. In the example above, the primary key is stored into cf_link_pk column family, and id1_type index data is stored into rev:cf_link_id1_type column family.

  • MyRocks has also a feature called reverse column family. Reverse column family is useful if the index is mainly used for descending scan (ORDER BY ... DESC). You can configure reverse column family by setting rev: before the column family name. In this example, id1_type belongs to a reverse column family.

  • For a given table, MyRocks supports storing column families on a per partition basis. More information on how to specify the column families is in Column Families on Partitioned Tables.

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