Exercise 15.1 Briefly answer the following questions: In the context of query optimization...
Exercise 15.1 Briefly answer the following questions:
In the context of query optimization, what is an SQL query block?
Define the term reduction factor.
Describe a situation in which projection should precede selection in processing a project-select query, and describe a situation where the opposite processing order is better. (Assume that duplicate elimination for projection is done via sorting.)
If there are unclustered (secondary) B+ tree indexes on both R.a and S.b, the join could be processed by doing a sort-merge type of join—without doing any sorting—by using these indexes.
Would this be a good idea if R and S each has only one tuple per page or would it be better to ignore the indexes and sort R and S? Explain.
What if R and S each have many tuples per page? Again, explain.
Explain the role of interesting orders in the System R optimizer.
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