postgresql - SQL - select rows until aggregate is matched -

i have table of packages. each packages has priority , weight:

priority | weight ----------------- 1         4 2         3 3         5 4         1 5         3 

i want fit packages, sorted priority, box, until maximum allowed weight of box reached. example, if have box of maximum allowed weight 10, pick following 2 packages:

priority | weight ----------------- 1         4 2         3 

in sql words, want keep select * package order priority long sum(weight) <= 10.

is possible in postgresql 9.x?

you can use window function sum order by clause calculate cumulative sum of weight in order of priority , filter on that.

select priority, weight (     select t.*,         sum(weight) on (             order priority             ) cuml_weight     your_table t     ) t cuml_weight <= 10; 

demo

as asked op, can done using correlated subquery:

select * (     select t.*,         (             select sum(weight)             your_table t2             t2.priority <= t.priority             ) cuml_weight     your_table t     ) t cuml_weight <= 10; 

demo