• consist of 256 [0..1000] values as short[256]

• contain many zero values (on average >200/256)

Scope for compression

• 16-bit quantities used for 10-bit values   (fixed-length compressed vectors)

• because of repetition of particular value (zero)   (variable-length compressed vectors)

Have implemented second:

• reduced storage costs and query I/O by around 2/3

• no increase in processing cost   (slight reduction)