HBase

Question 1

What does scan do?

Answer 1

Shows the items in the given file

Question 2

What is the coding syntax to create a table in the Hbase

Answer 2

create ‘’NAME, COLUMN FAMILY’’

Question 3

What is the coding syntax to input values into Hbase?

Answer 3

put ‘store’,’1’, ‘customer:name’ , ‘haseeb’

Question 4

What is the difference between ‘get’ and the ‘scan’

Answer 4

Get only returns one column, while scan gives the total output of the table.

Question 5

What are the key components of Hbase?

Answer 5

❑ Zookeeper: It does the co-ordination work between client and Hbase Master
❑ Hbase Master: Hbase Master monitors the Region Server
❑ RegionServer: RegionServer monitors the Region
❑ Region: It contains in memory data store(MemStore) and Hfile.
❑ Catalog Tables: Catalog tables consist of ROOT and META

Question 6

What are the elements of a Hbase Model?

Answer 6

HBase Data Model consists of following elements:

❑ Set of tables
❑ Each table with column families and rows
❑ Each table must have an element defined as Primary Key.
❑ Row key acts as a Primary key in HBase.
❑ Any access to HBase tables uses this Primary Key
❑ Each column present in HBase denotes attribute corresponding to object

Question 7

What are the limitations of Hbase?

Answer 7

❑ We cannot expect completely to use HBase as a replacement for traditional models. Some of the traditional models features cannot support by HBase
❑ HBase cannot perform functions like SQL. It doesn’t support SQL structure, so it does not contain any query optimizer
❑ HBase is CPU and Memory intensive with large sequential input or output access while as Map Reduce jobs are primarily input or output bound with fixed memory. HBase integrated with Map-reduce jobs will result in unpredictable latencies
❑ HBase integrated with pig and Hive jobs results in some time memory issues on cluster
❑ In a shared cluster environment, the set up requires fewer task slots per node to allocate for HBase CPU requirements

Question 8

This is to summarize an HBase table’s mappings:

Answer 8

This is to summarize an HBase table’s mappings:
❑ a row key maps to a list of column families
❑ a column family maps to a list of column qualifiers (columns)
❑ a column qualifier maps to a list of timestamps (versions)
❑ a timestamp maps to a value (the cell itself)