Slideshow:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Data structure used to keep information on the dynamic programming
algorithm
Data structure used for the Dynamic Programming algorithm for finding the best join ordering:
Values for all the one relation join results: (cost =0 because there is no intermediate result set)
- Suppose we want to find the
best ordering for
the following join:
R ⋈ S ⋈ T
- Data structure used to
find the
best
join order:
Explanation:
- Relations joined:
- List of relations that
are joined with each other
Example: R, S
- List of relations that
are joined with each other
- Estimated size of the
join result:
- The computed estimate of
the size of the
join result
Example: T( R ⋈ S ) = 50,000 tuples
- The size of the
join result is
independent of
the join ordering !!!
I.e.: T(R ⋈ S) = T(S ⋈ R) !!!
- The size of the
join result is
independent of
the join ordering !!!
- The computed estimate of
the size of the
join result
- Least cost for the
join ordering
- The lowest possible cost to
perform the join on the
given list of input relations
(The cost is discussed here: click here )
- The lowest possible cost to
perform the join on the
given list of input relations
- Join ordering that produces
the least cost in
field #3
- The specific ordering that
yield the
least cost
Example: S ⋈ R
- The specific ordering that
yield the
least cost
- Relations joined:
- Initial values: