CREATE statement is used to create a HBase table, in this section, I will explain how to create an HBase table from the shell, syntax, usage, and practice with some examples.
HBase stores rows in the tables and each table is split into ‘regions’. Those regions are distributed across the cluster, hosted and made available to client processes by the RegionServer process in the system. All rows in the tables are sorted between regions start and end key. Every single row is belonging to exactly one region and a region is served by a single region server at any given point of time
HBase Create Table from Shell
Use CREATE command to create a HBase table, It takes name and column family as mandatory arguments. The syntax to create the table is as follows.
Create Table Syntax
CREATE 'name_space:table_name', 'column_family'
Note that namespace for table name is optional and when not specified it creates a table in the default namespace. column_family is mandatory, at least one column family needed in order to create a table successfully. when not specified, it returns an error.
Create Table Examples
Below example creates an ’emp’ table in default namespace and sets the column family as ‘office’. Make sure you create a namespace before using with the table.
When trying to create a table with an already existing name regardless of column family (with the same or different column family), you will get the bellow error message.
HBase Tables in a namespace should be unique.
HBase Split Table
As explained in the beginning, HBase tables are split and stores date into several regions. When the table is created, by default, HBase allocates a single region to it. Let’s see an example of how to split the table to multiple regions and use the cluster effectively.
HBase Split Table Syntax
CREATE 'name_space:table_name', 'column_family' SPLITS => ['10', '20', '30', '40']
Below example creates a new table dep
Refer Internals of HBase table splitting for understanding how splitting works.
Use list to list all the tables. This is similar to show tables in Hive
Besides these above examples, there are multiple options you can use while creating a table. I will leave these to you to explore.
Let’s insert some data using Put command, refer to the link for more detail examples.
hbase(main):060:0> put ’emp’, ‘1’ , ‘office:name’, ‘Scott’ hbase(main):060:0> put ’emp’, ‘2’ , ‘office:name’, ‘Mark’ hbase(main):061:0> put ’emp’, ‘2’ , ‘office:gender’, ‘M’ hbase(main):062:0> put ’emp’, ‘2’ , ‘office:age’, ’30’ hbase(main):063:0> put ’emp’, ‘2’ , ‘office:age’, ’50Finally use the Scan command to fetch the data from a table.
Conclusion
In this tutorial, you have learned how to create an HBase table from shell command and also have seen an example of how to split the table into regions.
Related Articles
- How to list all and filter the HBase tables
- HBase – Get rows from Table with Examples
- HBase Disable and Enable Table with Examples
- HBase – List Tables with examples
- HBase – Scan or Select the table
- HBase Describe table with Examples
Happy Learning !!
