The MySQL Federated storage engine for the MySQL relational database management system is a storage engine which allows a user to create a table that is a local representation of a foreign (remote) table. It utilizes the MySQL client library API as a data transport, treating the remote data source the same way other storage engines treat local data sources whether they be MYD files (MyISAM), memory (Cluster, Heap), or tablespace (InnoDB). Each Federated table that is defined there is one .frm (data definition file containing information such as the URL of the data source). The actual data can exist on a local or remote MySQL instance.
To create a Federated table, one has to specify a URL in the "CONNECTION" string:
The connection URL is in the format of:
scheme://user:pass@host:port/schema/tablename
Upon creation of a Federated table, the user must ensure that the remote data source does indeed exist or an error will be issued.
The MySQL Federated Storage Engine was authored by Patrick Galbraith and Brian Aker and is currently being maintained by Patrick Galbraith and Antony Curtis. It was introduced in 2005 with MySQL 5.0.
Source of the article : Wikipedia
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