FEDERATED tables in MySQL are a type of storage engine that allows you to access data from a remote MySQL database without physically storing the data on the local server. This feature is particularly useful for distributed database architectures where data is spread across multiple databases or servers.
Key Features and Usage
Remote Data Access: The primary use of FEDERATED tables is to enable the querying of data from a remote server as if it were local. This means you can perform SQL operations like SELECT, INSERT, UPDATE, and DELETE on a remote table through a local table that acts as a proxy[1][2][4].
Setup and Configuration: To create a FEDERATED table, you must first ensure that the FEDERATED storage engine is enabled on your MySQL server. You then define a local table with the same structure as the remote table and specify the connection parameters (such as server, database, table, username, and password) in the CONNECTION string of the table definition[1][3][4].
Performance Considerations: While FEDERATED tables provide the convenience of remote data access, they can also introduce performance bottlenecks. Since the data is accessed over a network, operations that involve large amounts of data or complex queries might be slower compared to operations on local tables. Additionally, because the local server does not store the data, indexes on the FEDERATED table do not apply; the indexing capabilities of the remote table are used instead[2].
Limitations: There are several limitations to the use of FEDERATED tables. For instance, they do not support tran...
