This technical note covers the type of index used by 4D—the B-tree index. It describes what a
B-tree is, why and how it is used, and its advantages. The second part of this technical note will cover the disadvantages of B-tree indexes, some details about indexes in 4D, and possible alternatives to 4D indexes.
Among the features of every general purpose database engine is the ability to search for and retrieve data quickly. This capability is aided by the use of indexes. Conceptually, a database index is similar to other types of indexes, such a card catalog, telephone book, or the index in the back of a book. Basically, an index is a condensed representation of data that is organized in a manner that allows the program to quickly perform operations such as locating that data.