Query Optimization Flashcards
1
Q
Query optimization is conducted by DBMSs to select the _____ strategy for executing the query
A
best
2
Q
What is a query plan?
A
Relational algebra tree extended with annotations
3
Q
The annotations in a query plan tell which ______ ____ to use for each table and which ____________ _____ to use for each operator
A
access path, implementation method
4
Q
What are the 3 steps in query optimization?
A
- Enumerate alternative plans
- Estimating the costs
- Choosing the plan
5
Q
In pipelining, the results of an _________ is passed directly to the next
A
operator
6
Q
In materialization, the intermediate result is written to a temp _____
A
table
7
Q
The iterator interface hides the internal __________ ______ of each operator
A
implementation details
