Slideshow:
Definition of the join
(⋈)
operator
Using the definition of the join
(⋈) to re-write
a cartesian product
(×)
operator
Using the definition of the join
(⋈) to re-write
a cartesian product
(×)
operator
- Example
We have seen this previously:
- This identity is
are not
a "law"...
This identity is true because of the definition of the join (⋈) operator:
- The definition of the
join (⋈) operation is:
- The definition of the
join (⋈) operation is:
- The definition of ⋈ is
always used
in the reverse order in
query (re-writing) optimization:
