Engineering Questions with Answers - Multiple Choice Questions
MCQs on Cassandra with Hadoop – 2
1 - Question
_________ is a Cassandra feature that optimizes the cluster consistency process.
a) Hinted handon
b) Hinted handoff
c) Tombstone
d) Hinted tomb
View Answer
Answer: b
Explanation: You can enable or disable hinted handoff in the cassandra.yaml file.
2 - Question
Point out the correct statement.
a) Cassandra does not immediately remove data marked for deletion from disk
b) A deleted column can reappear if you do not run node repair routinely
c) The deletion of marked data occurs during compaction
d) All of the mentioned
View Answer
Answer: d
Explanation: Marking data with a tombstone signals Cassandra to retry sending a delete request to a replica that was down at the time of delete.
3 - Question
Cassandra searches the __________ to determine the approximate location on disk of the index entry.
a) partition record
b) partition summary
c) partition search
d) all of the mentioned
View Answer
Answer: b
Explanation: If the Bloom filter does not rule out the SSTable, Cassandra checks the partition key cache.
4 - Question
You configure sample frequency by changing the ________ property in the table definition.
a) index_time
b) index_interval
c) index_secs
d) none of the mentioned
View Answer
Answer: b
Explanation: By default, the partition summary is a sample of the partition index.
5 - Question
Point out the wrong statement.
a) A hint indicates that a write needs to be replayed to one or more unavailable nodes
b) When the cluster cannot meet the consistency level specified by the client, Cassandra does store a hint
c) By default, hints are saved for three hours after a replica fails because if the replica is down longer than that, it is likely permanently dead
d) All of the mentioned
View Answer
Answer: b
Explanation: When the cluster cannot meet the consistency level specified by the client, Cassandra does not store a hint.
6 - Question
The compression offset map grows to ____ GB per terabyte compressed.
a) 1-3
b) 10-16
c) 20-22
d) 0-1
View Answer
Answer: a
Explanation: The more you compress data, the greater number of compressed blocks you have and the larger the compression offset table.
7 - Question
The type of __________ strategy Cassandra performs on your data is configurable and can significantly affect read performance.
a) compression
b) collection
c) compaction
d) decompression
View Answer
Answer: c
Explanation: Using the SizeTieredCompactionStrategy or DateTieredCompactionStrategy tends to cause data fragmentation when rows are frequently updated.
8 - Question
There are _________ types of read requests that a coordinator can send to a replica.
a) two
b) three
c) four
d) all of the mentioned
View Answer
Answer: b
Explanation: The coordinator node contacts one replica node with a direct read request.
9 - Question
_________ can be configured per table for non-QUORUM consistency levels.
a) Read repair
b) Read damage
c) Write repair
d) None of the mentioned
View Answer
Answer: a
Explanation: If the replicas are inconsistent, the coordinator issues writes to the out-of-date replicas to update the row to the most recent values. This process is known as read repair.
10 - Question
If the table has been configured with the __________ property, the coordinator node for the read request will retry the request with another replica node.
a) rapid_retry
b) speculative_retry
c) speculative_rapid
d) none of the mentioned
View Answer
Answer: b
Explanation: Rapid read protection allows Cassandra to still deliver read requests when the originally selected replica nodes are either down or taking too long to respond.