Other Query Processing Strategies

In addition to the optimization strategies covered so far, SQL Server also has some additional strategies it can apply for special types of queries. These strategies are employed to help further reduce the cost of executing various types of queries.

Predicate Transitivity

You might be familiar with the transitive property from algebra. The transitive property simply states that if A=B and B=C then A=C. SQL Server supports the transitive property in its query predicates. Predicate transitivity enables SQL Server to infer a join equality from two given equalities. Consider the following example:

SELECT * 
   FROM table1 t1
   join table2 t2 on t1.column1 = t2.column1
   join table3 t3 on t2.column1 = t3.column1

Using the ...

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