On 10/10/2025 10:51, Frits Jalvingh wrote:
Hi Andrei,
Thanks a lot for your response. I do not fully get it though because the
well-performing query also references the outer (external?) relation:
-> where eenheid.id_h_eenheid = eenheid_s.id_h_eenheid
But your response made me think a but more.This is the schema of EXPLAIN for
the second 'optimal' query:
Seq Scan on s_h_eenheid_ssm D
SubPlan 2
-> Hash Join
Hash Cond: (A.x = B.x)
-> Seq Scan on A
Filter: ...
-> Hash
-> Hash Join
Hash Cond: (C.y = B.x)
-> Seq Scan on s_h_huurovereenkomst_ssm C
-> Hash
-> Seq Scan on s_h_eenheid_ssm B
There is no reference to the upper relation D - each HashJoin refers to
its left and right side only.
-- regards, Andrei Lepikhov, pgEdge
