1. If you have not too much information for the essbase, you don't need to make any compression setting on the Essbase. By default, the essbase is compressed using BITMAP which is the best way in most cases.
2. If your essbase is 90% dense, you may use ZLIB for the compression method
3. If your Essbase is sparse, and you have huge repeated nonmissing data cells, you should use RLE for essbase compression method.
By the way, the "Index Value Pair" compression is selected automatically by the Essbase system. Index Value Pair addresses compression on databases with larger block sizes, where the blocks are highly sparse. This compression algorithm is not selectable but is automatically used whenever appropriate by the database. The user must still choose between the compression types None, bitmap, RLE, and zlib through Administration Services.
