CASSANDRA CQL and Data Modeling 3

Question 1

What does a CQL BATCH statement guarantee in Cassandra?

Accepted Answer

Atomicity for mutations to a single partition (logged batch)

Answer

ACID transactions across multiple partitions

Answer

Distributed joins between tables

Answer

Ordered execution of statements across nodes

Question 2

Which CQL function generates a new unique time-based UUID suitable for use as a clustering key?

Accepted Answer

now()

Answer

uuid()

Answer

toTimestamp()

Answer

currentTime()

Question 3

In Cassandra, what is 'upsert' behavior?

Accepted Answer

Cassandra always treats INSERT and UPDATE as an upsert — existing rows are overwritten at the cell level

Answer

Cassandra throws an error if a row already exists during INSERT

Answer

Cassandra merges new and existing rows using a conflict resolution algorithm

Answer

Cassandra requires a prior SELECT to check existence before writing

Question 4

What is the purpose of the FROZEN keyword in CQL when used with collections or UDTs?

Accepted Answer

Serializes the entire collection/UDT as a single blob, preventing partial updates

Answer

Marks the column as read-only

Answer

Compresses the collection on disk

Answer

Enables secondary indexing on nested fields

Question 5

What CQL command is used to examine the current schema of a table, including its primary key and options?

Accepted Answer

DESCRIBE TABLE tablename

Answer

SHOW CREATE TABLE tablename

Answer

EXPLAIN TABLE tablename

Answer

SELECT * FROM schema_tables WHERE name='tablename'

Question 6

What is a user-defined type (UDT) in Cassandra CQL?

Accepted Answer

A named group of typed fields that can be embedded as a column value in a table

Answer

A custom compaction strategy

Answer

A stored procedure written in Java

Answer

A custom partition key type