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SQL Query Optimization and Execution Worksheet

Authored by Nandhini TJ

Engineering

University

Used 1+ times

SQL Query Optimization and Execution Worksheet
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93 questions

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1.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

A banking analytics system receives SQL queries joining three tables: Accounts, Transactions, and Customers. The optimizer rewrites the query tree before execution. Which transformation occurs during this stage?

Logical optimization through heuristic rules

Query parsing and translation into relational algebra

Execution plan generation

Cost estimation using statistics

2.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

A data warehouse query SELECT * FROM Sales WHERE amount>1000 AND region='APAC' passes through several stages. Which step determines which indexes or scans are used?

Parsing

Evaluation/Execution planning

Syntax checking

Logical transformation

3.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

A government tax portal executes complex joins. What metric does the planner use to estimate cost?

Number of queries

CPU usage only

Number of disk I/Os and tuple comparisons

Cache miss rate

4.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

In an OLTP system, optimizer chooses between join types. Orders fits in memory but Products does not. Which plan minimizes I/O?

Merge join

Block nested loop join

Cartesian join

Index join

5.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Optimizer converts a subquery in WHERE clause into a join. What is this process?

Physical optimization

Query rewriting (logical optimization)

Parsing

Execution

6.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

An ecommerce dashboard runs SELECT COUNT(*) FROM Orders WHERE status='Shipped' using index on status. What happens during execution?

Index ignored

Index scan counts tuples without fetching full rows

Full table scan

Cached result

7.

MULTIPLE CHOICE QUESTION

30 sec • 1 pt

Temporary relations are created during query execution. Which operator generates the largest temporary relation?

Projection

Join

Selection

Aggregation

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