Re: When and how many times does ExecSetParamPlan executes?

Vaibhav Kaushal <vaibhavkaushal123@gmail.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;
QUERYPLAN                                  
 
-----------------------------------------------------------------------------Seq Scan on public.int8_tbl
(cost=1.07..2.12rows=5 width=16)  Output: int8_tbl.q1, int8_tbl.q2, $0  InitPlan 1 (returns $0)    ->  Aggregate
(cost=1.06..1.07rows=1 width=4)          Output: sum(int4_tbl.f1)          ->  Seq Scan on public.int4_tbl
(cost=0.00..1.05rows=5 width=4)                Output: int4_tbl.f1
 
(7 rows)

$0 here represents the PARAM_EXEC Param.
        regards, tom lane