  Data compression schemes have exhibited their importance in column databases
by contributing to the high-performance OLAP (Online Analytical Processing)
query processing. Existing works mainly concentrate on evaluating compression
schemes for disk-resident databases as data is mostly stored on disks. With the
continuously decreasing of the price/capacity ratio of main memory, it is the
tendencies of the times to reside data in main memory. But the discussion of
data compression on in-memory databases is very vague in the literature. In
this work, we present an updated discussion about whether it is valuable to use
data compression techniques in memory databases. If yes, how should memory
databases apply data compression schemes to maximize performance?
