The Ultimate Guide to High Availability with MariaDB

Cassandra storage engine

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This page is a documentation for Cassandra storage engine which is a work in progress.

This page describes a feature that's under development. The feature has not been released (even in beta), its interface and function may change, etc.

Cassandra table

MariaDB's table represents a column family in Cassandra. The table must follow this pattern:

create table cassandra_tbl               -- name can be chosen at will
(
  rowkey  char(N),                       -- First field must be named 'rowkey'. This
                                         --   is what Cassandra's row key is mapped to.

  column1    varchar(N),                 -- columns go here
  ... 
  PRIMARY KEY(rowkey)                    -- Primary key over 'rowkey' is mandatory
) engine=cassandra 
  thrift_host='192.168.1.0' 
  keyspace= 'cassandra_key_space'
  column_family='column_family_name';

MariaDB's table is a view of Cassandra's column family.

  • column family must exist before the MariaDB table can be created
  • dropping MariaDB's table will not drop the column family.

How columns are mapped

Cassandra has three kinds of columns

  1. The row key. It is not considered to be a column by Cassandra, but MySQL/MariaDB do not have separate 'keys', so we make it a column.
  2. Columns that were present in static column family declaration. These columns have a defined name/data type.
  3. "Ad-hoc" columns that can be encountered in individual rows.

See also

  1. cassandra-storage-engine-future-plans
  2. hbase-storage-engine

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