Big Data Interview Questions and Answers-Hbase
1. When should we use hbase ?
when we need to work with billions of rows and millions of columns, hbase is the best.
2. Difference b/w hbase and hdfs ?
HDFS is a distributed file system for storing and managing large data across clusters. HBase built on top of HDFS and it provides fast record lookups
3.why to use Hbase?
High capacity storage system.Distributed design to cater large tables.Column-Oriented Stores.Horizontally Scalable.High performance & Availability.supports random real time CRUD operations.
4.why to use Hbase?High capacity storage systemDistributed design to cater large tablesColumn-Oriented StoresHorizontally ScalableHigh performance & Availabilitysupports random real time CRUD operations
5. Mention how many operational commands in Hbase?Operational command in Hbases is about five typesGetPutDeleteScanIncrement
6) In Hbase what is column families?Column families comprise the basic unit of physical storage in Hbase to compression are applied.
7) What is the use of row key ?The use of row key is to have logical grouping of cells which ensures all cells with the same row-key are co-located on the same server.
8) Explain deletion in Hbase? Mention what are the three types of tombstone markers in Hbase?
When you delete the cell in Hbase, the data is not actually deleted but a tombstone marker is set, making the deleted cells invisible. So, Hbase deleted cells are actually removed during compaction.
Three types of tombstone markers are there:
Version delete marker: For deletion, it marks a single version of a columnColumn delete marker: For deletion, it marks all the versions of a columnFamily delete marker: For deletion, it marks of all column for a column family.
9) Explain how does Hbase actually delete a row?
Whatever you write will be stored from RAM to disk, It can write immutable barring compaction. Hence, during deletion process in Hbase, major compaction process delete marker while minor compaction don’t.
10) Explain what happens if you alter the block size of a column family on an already occupied database?
When you alter the block size of the column family, the new data occupies the new block size while the old data remains within the old block size. During data compaction, old data will take the new block size.
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