问题
Problem:
I am new to Hbase and I came across a situation where I need to join two tables.
Let us suppose I have Employee table and Department table both are created in Hbase. By reading Hbase in action , I got to know that we cannot join tables in Hbase.
Solution:
I found out a solution that by writing MapReduce Code using Hbase classes and Interfaces we can achieve this task.
Also if someone can help me with the coding that would be very helpful
回答1:
The easiest way would be to load your HBase tables into Hive or Impala and perform a SQL join with those tools.
回答2:
You should look at this jira issue in apache. You should use MultiTableInputFormat. https://issues.apache.org/jira/browse/HBASE-3996
See also: how to join tables in hbase
回答3:
Using Hive or Impala is costly when data is to large and we face issue like Hbase kill(region server Down) . so it is convenient when data is small but not for large Data. In mapreduce take Hbase table object to take one table and by extending tablemapper use 2nd table. By this way you can join 2 tables.
来源：https://stackoverflow.com/questions/25589288/how-to-join-two-tables-in-hbase