Analytics CBO is choosing suboptimal index paths

With the CBO, analytics optimizer is choosing two indexes and intersection when it can simply choose one index (wider one).

create a collection c and load some data; In my case, I loaded 1664 documents.

create index ic1a on c(a:int);

create index ic1b on c(a:int, b:int);

analyze analytics collection c;

select count(distinct uuid) from c 

where a = 1 and b between 100 and 200;

The plan shows the intersection of results from the two scans on ic1a and ic1b.

the plan can simply choose ic1b and be efficient. query_plan.txt