Data abstraction is the reduction of a particular body of data to a simplified representation of the whole.
Abstraction, in general, is the process of taking away or removing characteristics from something in order to reduce it to a set of essential characteristics. As in abstract art, the representation is likely to be one potential abstraction of a number of possibilities. A database abstraction layer, for example, is one of a number of such possibilities.
Data abstraction is usually the first step in database design. A complete database is much too complex a system to be developed without first creating a simplified framework. Data abstraction makes it possible for the developer to start from essential elements — data abstractions — and incrementally add data detail to create the final system.
Three Levels of data abstraction
Three levels of data abstraction are:
- Physical level : how the data is stored physically and where it is stored in database.
- Logical level : what information or data is stored in the database (like what is the datatype or what is format of data.
- View level : end users work on view level. if any amendment is made it can be saved by other name.
for the database to be usable it must retrieve data efficently.this efficency led designer to use complex data structure in the database