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.
1 T-SQL (Transact-SQL) 2  SQL CONSTRAINT clauses: FOREIGN KEY, CHECK and DEFAULT. 3  How to create a SQL inner join and outer join: Basics to get started. 4  Top 10 SQL Server development questions.