CASSANDRA Performance and Tuning

Question 1

What consistency level in Cassandra offers the lowest latency but the weakest consistency guarantee?

Accepted Answer

ONE

Answer

ALL

Answer

QUORUM

Answer

LOCAL_QUORUM

Question 2

What is the formula for calculating quorum in a Cassandra cluster?

Accepted Answer

(replication_factor / 2) + 1

Answer

(replication_factor / 2)

Answer

replication_factor - 1

Answer

replication_factor * 0.75

Question 3

What does 'speculative execution' do in Cassandra drivers?

Accepted Answer

Sends duplicate requests to multiple replicas and uses the fastest response to reduce tail latency

Answer

Pre-fetches the next page of results

Answer

Executes a query on a secondary index speculatively

Answer

Pre-compiles CQL statements to reduce parse overhead

Question 4

Which Cassandra compaction strategy minimizes read amplification and is best for mixed read/write workloads?

Accepted Answer

LeveledCompactionStrategy (LCS)

Answer

SizeTieredCompactionStrategy (STCS)

Answer

TimeWindowCompactionStrategy (TWCS)

Answer

DateTieredCompactionStrategy (DTCS)

Question 5

What is the 'row cache' in Cassandra and when should it be used?

Accepted Answer

An in-JVM cache of entire partitions for tables with very few partitions and high read frequency

Answer

A disk-based cache for recently flushed SSTables

Answer

A client-side cache maintained by the driver

Answer

A cache of CQL prepared statement results

Question 6

What tool can be used to run benchmark load tests against a Cassandra cluster?

Accepted Answer

cassandra-stress

Answer

nodetool benchmark

Answer

cqlsh --bench

Answer

sstableloader --test