Don't zero tuple_fraction when planning UNIONs with ORDER BYs Since 66c0185a3, the planner is able to use Merge Append -> Unique to implement UNION queries and each subquery is prompted to produce Paths correctly sorted by the UNION's targetlist.
Here we remove some now redundant code which was zeroing the tuple_fraction at the parent level. This will allow the planner to consider cheap startup paths when planning the UNION's subqueries. EXCEPT and INTERSECT set operations still have the tuple_fraction zeroed in generate_nonunion_paths(). These operations currently always read all of their subqueries' tuples. Reported-by: Tom Lane Discussion: https://postgr.es/m/3703023.1711654...@sss.pgh.pa.us Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/3b1a7eb28930e9835cda5e42256b7ccc2d044d41 Modified Files -------------- src/backend/optimizer/plan/planner.c | 11 ----------- 1 file changed, 11 deletions(-)
