ColumnEvictionConfig : For column level in-memory eviction, it’s the best effort TTL for in-memory data. Column level eviction has nothing to do with data availability, but based on how much data we pre-loaded, the major impact will be there for query performance. Here we bring in two priorities configs: Preloading days and Priority. Preloading days is defined at each column level to indicate how many recent days data we want to preload to host memory. This is best effort operation. Priority is defined at each column level to indicate the priority of each column. When data eviction happens, we will rely on column priority to decide which column will be evicted first. High number implies high priority.