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Query Optimization Techniques

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Questions and Answers

What is the primary goal of Query Optimization?

To reduce the size of a file by applying SELECT and PROJECT operations
To increase the size of a file by applying JOIN and Cartesian product operations
To maximize the number of tuples in the output
To execute the query in the least amount of time by minimizing the cost (correct)

What is the disadvantage of using SELECT *?

It selects the entire database, which is inefficient (correct)
It selects only the required columns
It is faster than selecting specific columns
It reduces the size of the output

Why should IN be avoided in favor of EXISTS?

IN and EXISTS have the same cost
IN is more efficient than EXISTS
IN is more costly than EXISTS (correct)
IN is faster than EXISTS

What is the purpose of the LIMIT command?

To limit the number of results displayed (B) Signup and view all the answers

What is the main factor influencing cost estimation in query optimization?

All of the above (D) Signup and view all the answers

What is the logical AND operator used for in query optimization?

To calculate the probability of two conditions being true (A) Signup and view all the answers

In a relational database, what happens when no value meets a specified condition?

It returns 0 (C) Signup and view all the answers

What is the purpose of the BASE structure in NoSQL databases?

To provide high availability and partition tolerance (A) Signup and view all the answers

What is the main advantage of using a graph-oriented model?

It is suited for storing and managing highly connected data (B) Signup and view all the answers

What is the purpose of the $mod operator in MongoDB?

It returns the remainder of a division operation (C) Signup and view all the answers

What is the default isolation level in MongoDB?

Read uncommitted (B) Signup and view all the answers

What is the purpose of the CYPHER language in Neo4J?

It is used to query graph databases (B) Signup and view all the answers