FEDERATED Storage Engine Overview-opracowanie

FEDERATED Storage Engine Overview
When you create a table using one of the standard storage engines (such as MyISAM, CSV or
InnoDB), the table consists of the table definition and the associated data. When you create a
FEDERATED table, the table definition is the same, but the physical storage of the data is handled on a
remote server.
A FEDERATED table consists of two elements:
• A remote server with a database table, which in turn consists of the table definition (stored in the
.frm file) and the associated table. The table type of the remote table may be any type supported by
the remote mysqld server, including MyISAM or InnoDB.
• A local server with a database table, where the table definition matches that of the corresponding
table on the remote server. The table definition is stored within the .frm file. However, there is no
data file on the local server. Instead, the table definition includes a connection string that points to
the remote table.
When executing queries and statements on a FEDERATED table on the local server, the operations that
would normally insert, update or delete information from a local data file are instead sent to the remote
server for execution, where they update the data file on the remote server or return matching rows from
the remote server.
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