On Sat, 27 Aug 2022 at 18:04, PG Doc comments form <nore...@postgresql.org> wrote: > > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/14/queries-with.html > Description: > > I believe that the second query in section 7.8.2 (Recursive Queries) should > be modified to properly account for quantities. In the recursive term, > p.quantity should be multiplied by pr.quantity: > > WITH RECURSIVE included_parts(sub_part, part, quantity) AS ( > SELECT sub_part, part, quantity FROM parts WHERE part = 'our_product' > UNION ALL > SELECT p.sub_part, p.part, p.quantity * pr.quantity > FROM included_parts pr, parts p > WHERE p.part = pr.sub_part > ) > SELECT sub_part, SUM(quantity) as total_quantity > FROM included_parts > GROUP BY sub_part > > As currently written, if a car has four wheels, and each wheel has five > bolts, the whole example returns five bolts for the parts of a car. With the > proposed change, it will return 20 bolts.
I agree, based on the attached test. psql -f parts.sql Existing sub_part | total_quantity ----------+---------------- wheel | 4 bolt | 5 (2 rows) Proposed change sub_part | total_quantity ----------+---------------- wheel | 4 bolt | 20 Doc patch attached. -- Simon Riggs http://www.EnterpriseDB.com/
parts.sql
Description: Binary data
recursive_correction.v1.patch
Description: Binary data
