Database Reference
In-Depth Information
Deining the Schema
In this chapter, we are going to learn some of the basic concepts of the column family
database, that is, HBase, and cover the following topics:
• Data modeling
• Designing tables
• CRUD operations
Let's dive in and start off by taking a look at how we can model data in HBase.
Data modeling in HBase
In the RDBMS world, data modeling has principles around tables, columns, data
types, size, and so on, and the only supported format is structured data. HBase
is quite different in this aspect, as in each row, it can store different numbers of
columns and data types, making it ideal for storing so-called semi-structured data.
Storing semi-structured data not only impacts the physical schema but also the
logical schema of HBase. For the same reason, some features such as relational
constraints are also not present in HBase.
Similar to a typical RDBMS, tables are composed of rows and these rows are composed
of columns. Rows in HBase are identiied by a unique rowkey and are compared with
each other at the byte level, which resembles a primary key in RDBMS.
In HBase, columns are organized into column families. There is no restriction on the
number of columns that can be grouped together in a single column family. This
column family is part of the data deinition statement used to create the HBase table.
