Query Optimization

Question 1

Query optimization is conducted by DBMSs to select the _____ strategy for executing the query

Answer 1

best

Question 2

What is a query plan?

Answer 2

Relational algebra tree extended with annotations

Question 3

The annotations in a query plan tell which ______ ____ to use for each table and which ____________ _____ to use for each operator

Answer 3

access path, implementation method

Question 4

What are the 3 steps in query optimization?

Answer 4

1. Enumerate alternative plans
2. Estimating the costs
3. Choosing the plan

Question 5

In pipelining, the results of an _________ is passed directly to the next

Answer 5

operator

Question 6

In materialization, the intermediate result is written to a temp _____

Answer 6

table

Question 7

The iterator interface hides the internal __________ ______ of each operator

Answer 7

implementation details