Free Test Query Optimization Tec... – Databas...

Q1: What is the main goal of query optimization?

A. To minimize the cost of query execution B. To maximize storage C. To encrypt data D. To backup data

Q2: Which of the following is a common heuristic in query optimization?

A. Perform selection operations before joins B. Perform joins before selection C. Ignore selections D. Always use full table scans

Q3: What is predicate pushdown?

A. Migrating selection conditions closer to data retrieval operations B. Moving data to cache C. Encrypting predicates D. Ignoring filters

Q4: What is join reordering?

A. Rearranging the order of joins to optimize query performance B. Ignoring join conditions C. Removing joins D. Duplicating joins

Q5: Which join algorithm is generally most efficient for small datasets?

A. Nested-loop join B. Hash join C. Sort-merge join D. Cartesian join

Q6: What does a cost model estimate in query optimization?

A. Resources like CPU, I/O, and memory used by query plans B. Query text C. Data size D. Backup time

Q7: Which method helps avoid generating all possible query plans?

A. Heuristics B. Exhaustive search C. Random search D. Brute force

Q8: What is selectivity estimation?

A. Estimating the fraction of tuples that satisfy a condition B. Data encryption C. Storage allocation D. Query parsing

Q9: Which join technique uses a hash table for matching tuples?

A. Hash join B. Nested-loop join C. Sort-merge join D. Cartesian join

Q10: What is a bushy tree in query optimization?

A. A join tree where both children are results of joins B. A single table scan C. A linear chain of joins D. A backup plan

Q11: What does the term "interesting order" mean in optimization?

A. Orderings that can be used by subsequent operations to improve efficiency B. Sorting data randomly C. Ignoring order D. Backup order

Q12: Which is NOT a query optimization technique?

A. Data replication B. Join reordering C. Predicate pushdown D. Use of indexes

Q13: What is plan caching in query optimization?

A. Saving query plans for reuse B. Deleting old data C. Backing up indexes D. Encrypting queries

Q14: Which cost metric is most important for query optimization?

A. I/O cost B. Encryption overhead C. Storage capacity D. Backup time

Q15: What does "query rewrite" mean?

A. Transforming query into an equivalent but more efficient form B. Deleting queries C. Backing up queries D. Encrypting queries

Q16: What is a semi-join?

A. A join that returns only attributes from one relation B. A full join C. A cross join D. A backup join

Q17: What is the impact of statistics on query optimization?

A. Better statistics improve plan selection accuracy B. They have no impact C. They slow down queries D. They cause errors

Q18: What is dynamic programming used for in query optimization?

A. Systematically finding the best join order B. Encrypting data C. Backing up data D. Writing queries

Q19: Which join type is preferred for sorted relations?

A. Sort-merge join B. Hash join C. Nested-loop join D. Cartesian join

Q20: What is the purpose of query hints?

A. To guide the optimizer in choosing certain plans B. To encrypt queries C. To store data D. To backup queries

Quiz for Query Optimization Techniques