CASSANDRA MCQ 5

Question 1

Which Cassandra feature enables compare-and-swap (CAS) operations to prevent race conditions?

Accepted Answer

Lightweight transactions (LWT) using IF clauses

Answer

Lightweight transactions use the Paxos consensus protocol to implement conditional updates (INSERT IF NOT EXISTS, UPDATE IF col = val), providing linearizable consistency.

Question 2

What is the function of nodetool decommission?

Accepted Answer

Gracefully removes a node from the ring after streaming its data to other replicas

Answer

`nodetool decommission` safely removes a node by streaming its token ranges to neighboring nodes before leaving the ring.

Question 3

What is a tombstone in Apache Cassandra?

Accepted Answer

A marker written to represent a deletion, which is purged after the gc_grace_seconds period

Answer

Cassandra uses tombstones to flag deleted data; they are retained for gc_grace_seconds to prevent deleted data from reappearing via hinted handoff, then removed during compaction.

Question 4

Which CQL data type is used to store a universally unique identifier generated natively by Cassandra?

Accepted Answer

timeuuid

Answer

timeuuid (version 1 UUID) embeds a timestamp, enabling time-ordered sorting and the use of now() and dateOf() functions in CQL.

Question 5

What is the recommended approach to add a new datacenter to an existing Cassandra cluster without downtime?

Accepted Answer

Bootstrap new nodes in the datacenter, then run nodetool rebuild on each to stream data

Answer

New nodes join the ring, and `nodetool rebuild` streams the required token ranges from an existing datacenter, allowing a live, zero-downtime datacenter addition.

CASSANDRA - Apache Cassandra Database Practice Test

CASSANDRA - Apache Cassandra Database Practice Test

CASSANDRA MCQ 5