Data access performance using decompression maps

A computer program product for decompressing data in a database system, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code being executable by a processor to:

• receive, by the processor, a query pertaining to a subset of data within a compressed set of data;
• evaluate, by the processor, one or more decompression strategies using a cost model, the cost model including an estimated filter factor;
• select, by the processor, a low cost decompression strategy based on the results of the evaluation of the one or more decompression strategies;
• locate, by the processor, one or more bytes representing the requested subset of data within the compressed set of data;
• and
• decompress, by the processor, only a portion of the compressed data that corresponds to the subset of data, using the selected decompression strategy, while leaving the remaining set of data in a compressed state.