Query execution algorithms

The function of the optimizer is to translate certain SQL statements (SELECT, INSERT, UPDATE, or DELETE) into an efficient access plan made up of various relational algebra operators (join, duplicate elimination, union, and so on). The operators within the access plan may not be structurally equivalent to the original SQL statement, but the access plan's various operators will compute a result that is semantically equivalent to that SQL request.


Relational algebra operators in access plans
Parallelism during query execution
Table access methods
Types of algorithms