--! qt:transactional
set hive.strict.checks.type.safety=false;

create table sketch_input (id int, category char(1))
STORED AS ORC
TBLPROPERTIES ('transactional'='true');

insert into table sketch_input values
  (1,'a'),(1, 'a'), (2, 'a'), (3, 'a'), (4, 'a'), (5, 'a'), (6, 'a'), (7, 'a'), (8, 'a'), (9, 'a'), (10, 'a'),
  (6,'b'),(6, 'b'), (7, 'b'), (8, 'b'), (9, 'b'), (10, 'b'), (11, 'b'), (12, 'b'), (13, 'b'), (14, 'b'), (15, 'b'),
  (1,null),(2,null),(10,null),(13,null);
; 

select id,category,ntile(4) over (partition by category order by id) from sketch_input order by category,id;

select id,category,
		ntile(4) over (partition by category order by id),
		case when ceil(ds_kll_cdf(ds, CAST(id AS FLOAT) )[0]*4) < 1 then 1 else ceil(ds_kll_cdf(ds, CAST(id AS FLOAT) )[0]*4) end
from sketch_input
join ( select category as c,ds_kll_sketch(cast(id as float)) as ds from sketch_input group by category) q on (q.c=category)
order by category,id;

set hive.optimize.bi.enabled=true;

-- see if rewrite happens
explain
select id,'rewrite',ntile(4) over (partition by category order by id) from sketch_input order by category,id;

select id,'rewrite',ntile(4) over (partition by category order by id) from sketch_input order by category,id;