PRE_LOAD_CACHE - Result column preloads and COMPARES the column into the memory, prior to EXECUTING the lookup.PRE_LOAD_CACHE is used when the table can exactly fit in the memory space.
DEMAND_LOAD_CACHE - Result column loads and compares the column into the memory when a FUNCTION performs the execution.DEMAND_LOAD_CACHE is suitable while looking up the highly repetitive values with small subset of data.