Does not contain the data anymore.
It is distributed across shards.Root
Horizontal scaling 3
- contains federation metadata;
- global database data;
- route connections.
- provides physical data separation;
- can have its own schema;
- the collection of all rows in a
federation member that match
a specific federation key value.
• The federation distribution key must be an
INT, BIGINT, UNIQUEIDENTIFIER, or VARBINARY and specifies a
• Federation columns cannot be NULL-able.
• Federated members do not support the IDENTITY property.
• Reference tables cannot have foreign key relationships with federated
tables. Federated tables can have foreign key relationships with
reference tables without restrictions.
• Each federation member cannot be larger than 150 GB.
• Cross database joins are not supported. An application must implement
the logic for joining data from multiple federation members or multiple
Federations in Windows Azure SQL Database:
SQL Database Federations Tutorial:
Federation Guidelines and Limitations: