Database Reference
In-Depth Information
CHAPTER 3
Indexes and Composite Columns
In previous chapters we have discussed big data problems, Cassandra data modeling
concepts, and various schema management techniques. Although you should avoid nor-
malizing the form of your data too much, you still need to model read requirements
around columns rather than primary keys in your database applications.
The following topics will be covered in this chapter
•
Indexing concept
•
Data partitioning
•
Cassandra read/write mechanism
•
Secondary indexes
•
Composite columns
•
What's new in Cassandra 2.0
Indexes
An index in a database is a data structure for faster retrieval of a data set in a table. In-
dexes can be made over single or multiple columns.
Indexing is a process to create and manage a data structure called Index for fast data
retrieval. Each index consists of indexed field values and references to physical records.
In some cases a reference can be an actual row itself. We will discuss these cases in the
clustered indexes
section.
Physically data is stored on blocks in data structure form (like sstable in Cassandra).
These data blocks are unordered and distributed across multiple nodes. Accessing data
