Database Reference
In-Depth Information
Variety
One type (relational)
Four main types: document, column-oriented, key-value, and graph
Structure
Predefined
Dynamic
Scaling
Primarily vertical
Primarily horizontal
Focus
Data integrity
Data performance and availability
VARIETY
RDBMS have one type of structure (relational) where individual records are stored as rows
in tables, with each column storing a specific piece of data about that record. When data
is needed from more than one table, these tables are joined together. For example, offices
might be stored in one table and employees in another. When a user wants to find the work
address of an employee, the Employee and Office tables are joined together. NoSQL has
four main varieties, and each will be described shortly: document, column-oriented, key-
value, and graph. Each variety has its own way of storing data. An RDBMS has tradition-
ally been chosen as the solution for every type of operational or analytical scenario. NoSQL
solutions, however, excel in particular scenarios and therefore are used for specific types
of situations (e.g., a graph database is often used in scenarios where a document database
would be inefficient).
STRUCTURE
The RDBMS database structure is predefined. To store information about a new property,
we need to modify the structure before we can add the data. Before we can add all of our
employees' birth dates, we first need to create the Employee Birth Date field. The NoSQL
structures are typically dynamic. New types of information can be added as needed without
having to reload data or rebuild database structures.
SCALING
RDBMS are usually just scaled vertically, meaning a single server must be upgraded in
order to deal with increased demand. NoSQL databases are usually scaled horizontally,
meaning that to add capacity, a database administrator can add more inexpensive servers or
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