Explanation/Reference:
Hyperion recommends that you should turn compression off if you have a block density > 90% (rarely happens) and you should change to RLE compression when the block density is < 3% (or if you have all the same values in the database - lots of zeros).
Note: You may want to disable data compression if blocks have very high density (90% or greater) and have few consecutive, repeating data values. Under these conditions, enabling compression consumes resources unnecessarily. Don't use compression if disc space/memory is not an issue compared to your application. It can become a drain on the processor.