Rearranging Relational Algebra Expressions
Can the select be done before the join?
- In general, this can be done for predicates that refer to
columns from one input to the join. Which is extremely common.
- "Pushing the select below the join" is a very important
- Query optimization involves discovering rearrangements like this,
estimating the cost of each, and picking the cheapest alternative.
A faster version of the query
What are the titles of albums by The Detroit Cobras?
name == 'The Detroit Cobras')
select(Artist, name == 'The Detroit Cobras'),