Re: When and how many times does ExecSetParamPlan executes?

Vaibhav Kaushal <vaibhavkaushal123(at)gmail(dot)com> writes:
> So, I think that the function ExecSetParamPlan (as the code suggests
> too) is called _once_ in any plan/expression and that should be mostly
> for a sub-select query.

> Kindly correct me if I am wrong. Since I am not able to understand this
> usecase completely, a sample query which is capable of calling this
> function (ExecSetParamPlan) could show some light. It would be really
> kind of you / anyone to show me a query executable through psql which
> can actually call ExecSetParamPlan and involves the use of a on-disk
> relation.

regression=# explain verbose select *, (select sum(f1) from int4_tbl) ss from int8_tbl;
QUERY PLAN
-----------------------------------------------------------------------------
Seq Scan on public.int8_tbl (cost=1.07..2.12 rows=5 width=16)
Output: int8_tbl.q1, int8_tbl.q2, $0
InitPlan 1 (returns $0)
-> Aggregate (cost=1.06..1.07 rows=1 width=4)
Output: sum(int4_tbl.f1)
-> Seq Scan on public.int4_tbl (cost=0.00..1.05 rows=5 width=4)
Output: int4_tbl.f1
(7 rows)

$0 here represents the PARAM_EXEC Param.

regards, tom lane