An extract dataset, or short extract, is a dataset in the internal session of an ABAP program that is not handled as a data object and therefore has no data type. There is only one extract dataset for every ABAP program. It can be filled will ABAP statements and read. The content of the extract dataset cannot be explicitly deleted.
In the same way as an internal table, an extract dataset is made up of a dynamic number of lines. The size of the extract dataset is theoretically unlimited, if the size exceeds 500 KB, it is stored in a file of the operating system. Sizes of up to 2 GB (and larger for 64-bit processors) are practicable. In contrast to internal tables, the individual lines can have different structures. The line structures are declared using the statement FIELD-GROUPS.
The exact structure of each line is not determined until the program is executed using the statement INSERT.
The statements used for processing extracts are: