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♣ Tip: Before going through this Apache HBase interview questions, I would suggest you to go through Apache HBase Tutorial and HBase Architecture to revise your HBase concepts.
Now moving on, let us look at the Apache HBase interview questions.
What do you mean by WAL?
It stands for Write Ahead Log. It is basically a log that is responsible for recording all the changes in the data irrespective of the mode of their change. Generally, it is considered the standard sequence file. It is actually very useful to consider after the issues like a server crash or failure. The users can still access data through it during such problems.
2 Tell a few important features of the Apache Hbase?
The following are the features of the Apache Hbase
What constitutes a cell in HBase?
Cells are the smallest units of HBase tables, holding the data in the form of tuples. A tuple is a data structure having multiple parts. In HBase, it consists of {row, column, version}.
1 Discuss deletion and tombstone markers in HBase.
In HBase, a normal deletion process results in a tombstone marker. The deleted cells become invisible, but the data represented by them is actually removed during compaction. HBase has three types of tombstone markers:
Here, it needs to be noted that a row in HBase would be entirely deleted after major compaction. Therefore, when you delete and add more data, the Gets may be masked by tombstone markers, and you may not see the inserted values until after the compactions.
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Compare Hbase and Hive and tell the noticeable differences?
Both are based on Hadoop but both are different from one another. Hive is generally considered as one of the best available data warehouse infrastructure. The operations of Hbase are limited when compared to the Hive. However, when it comes to handling real-time operations, the Hbase is good. On the other hand, the Hive is preferred only when the querying of data is the prime need.
| Related Article: Hive vs HBase |