If Drill has more than 20 in-lists , Drill can do an optimization to convert that in-lists into a small hash table in memory, and then do a table join instead.
This can improve the performance of the query which has many in-lists.
Could we make "20" configurable? So that we do not need to add duplicate/junk in-list to make it more than 20.
Sample query is :
select count from table where col in (1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1);