Three types of buffering can be found in SAP ABAP, that can be configured for a database view or database table in ABAP Dictionary. They are:
SAP Buffer - Single Record Buffering : In this type of buffering, only actually accessed rows in the table will be buffered. It needs less space in the buffer when compared to generic or full buffering. But it requires more amount of administration work and direct database access. If SELECT SINGLE is used for accessing a non-buffered row, it tries to load the row. If the row is not available, this will be noted in the buffer and the database will not again access the next time SELECT SINGLE has been used.
SAP Buffer - Generic Buffering : In this type of buffering, SAP buffer will be loaded with all rows that match a row(on which read is performed) in a left-justified part of the primary key. The count of key fields covered is mentioned within the definition and will be always less than the key field’s total count. Altogether, these key fields are considered as the generic key. Each generic area will be managed similarly as standalone views or tables whose primary key will be the generic key and that are fully buffered.
SAP Buffer - Full Buffering : In this buffering, on reading a row, all rows in the view or table will be loaded into the SAP buffer. The buffered view or table will be either completely in the buffer or not at all. In the buffer, the buffered data records will be sorted on the Key of the view or table basis. Optimized access needs the left-justified part of the primary key/the secondary index fields to be as large as possible. If not, the buffer will be scanned in a linear format.
