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HBase NoSQL Interview Preparation (Q&A)



Question-31 : How "Randomization" helps in Time series data ?

Answer : A totally different approach is to randomize the row key using, for example:
byte[] rowkey = MD5(timestamp)
Using a hash function like MD5 will give you a random distribution of the key across all available region servers. For time series data, this approach is obviously less than ideal, since there is no way to scan entire ranges of consecutive timestamps. On the other hand, since you can re-create the row key by hashing the timestamp requested, it still is very suitable for random lookups of single rows. When your data is not scanned in ranges but accessed randomly, you can use this strategy.Summarizing the various approaches, you can see that it is not trivial to find the right balance between optimizing for read and write performance. It depends on your access pattern, which ultimately drives the decision on how to structure your row keys.


Question-32 : List the main component of HBase?

Answer : Zookeeper, Catalog Tables , Master , RegionServer , Region


Question: Please tell us Operational command in Hbase, we you have used ?

Answer : There are five main command in HBase.
Get
Put
Delete
Scan
Increment


Question: Write down the Java Code snippet to open a connection in Hbase?

Answer : If you are going to open connection with the help of Java API. The following code provide the connection
Configuration myConf = HBaseConfiguration.create(); HTableInterface usersTable = new HTable(myConf, "users");

Related Questions


Question: BlcokSize is configured on which level ?

Question: If your requirement is to read the data randomly from HBase User table. Then what would be your preference to keep blcok size.

Question: What is a block, in a BlockCache ?

Question: While reading the data from HBase, from which three places data will be reconciled before returning the value ?

Question: Once you delete the data in HBase, when exactly they are physically removed ?

Question: Please describe minor compaction

Question: Please describe major compactation ?

Question: What is tombstone record ?