Cache and Raid performance. One of the key limitations of spinning disk hardware is the use of a physical reading armature and the time this takes to move across the surface of a diskâs platter to the required data blocks.
Constraints are part of a database schema definition. A constraint is usually associated with a table and is created with a CREATE CONSTRAINT or CREATE ASSERTION SQL statement. They define certain properties that data in a database must comply with.
If a source table has a foreign key constraint note that the SQL Server Import and Export Wizard does not load tables a specific order for constraints, and it is possible that a table containing a foreign key will get loaded before a table containing a referenced primary key, which will cause a foreign key constraint failure.