Knowing how 4D stores data, organizes the data file (<< .4DD >> file) and uses indexes is important for two main reasons:

- Understanding how our development tool works is part of the Fundamental Knowledge,

- It will help to improve the performances (speed and/or storage volume) of our database, and it sometimes can dramatically improve it.

As it is a huge subject, we divided it in two sessions: the first one will focus on explanations and fundamental knowledge about records storage and indexes; the second session will focus on optimizations (using indexes in queries and sorts, choosing types of fields, ...). In the current document, we’ll focus on the main explanations about data storage, the sessions go more in-depth. A component is provided, to illustrate the concepts and to help you to analyze your data.