Exercise 14.1 Briefly answer the following questions: Consider the three basic techniques,...
Exercise 14.1 Briefly answer the following questions:
Consider the three basic techniques, iteration, indexing, and partitioning, and the relational algebra operators selection, projection, and join. For each technique-operator pair, describe an algorithm based on the technique for evaluating the operator.
Define the term most selective access path for a query.
Describe conjunctive normal form, and explain why it is important in the context of relational query evaluation.
When does a general selection condition match an index? What is a primary term in a selection condition with respect to a given index?
How does hybrid hash join improve on the basic hash join algorithm?
Discuss the pros and cons of hash join, sort-merge join, and block nested loops join.
If the join condition is not equality, can you use sort-merge join? Can you use hash join? Can you use index nested loops join? Can you use block nested loops join?
Describe how to evaluate a grouping query with aggregation operator MAX using a sorting-based approach.
Suppose that you are building a DBMS and want to add a new aggregate operator called SECOND LARGEST, which is a variation of the MAX operator. Describe how you would implement it.
Give an example of how buffer replacement policies can affect the performance of a join algorithm.
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