A.HDFS

B.Kafka

C.HBase

D.Redis

A.uniq operation, for example, get the weight value of all data in a certain period of time

B.Get the latest N data operations: for example, get the latest 10 comments on a Weibo

C.Build a queue system, such as a message queue

D.Simulate stack operation

A.If the client and the connected DataNode fail during reading, the client will abandon the failed node and connect to the node where the other replica is located.

B.Support multiple clients to read the same file data from the DataNode at the same time.

C.The file data is first returned from the DataNode to the NameNode, and then sent from the NameNode to the client.

D.Download data from the nearest DataNode first.

A.Scala

B.Java

C.C

D.Python

A.The MemStore setting of the Region exceeds the threshold

B.The total memory of RegionServer exceeds the threshold

C.Initiate Flush operation through the client specified method

D.The scan caching is set too large when the client initiates a scan request