Haisheng, No I included just 4-5 rules which I don't think they tinker with
subqueries.
I found SubQueryRemoveRule with three configs.
Are there any others too? Please let us know.
I don't want to include this rule because I want to maintain these
structures post-optimization too.
Julian, Yes I was referring to scalar subqueries.
The subqueries if they are in a Rex Form are not picked up for optimization
by default.
If someone from the core team wants to expand on this please do, I might be
wrong.
I support the above statement because the Rel Inside the RexSubQuery was
NOT optimized.
But with the same set of rules, it got optimized when sent to HepPlanner as
the main rel.
As of now, I will be writing a new Rule which basically does exactly what
Julian said of scanning Rexes for RexSubquery
and applying rules on them.
This rule will need to be added to the Rule List so it's not enabled by
default.
Please let me know a more graceful/optimized way to do this if any.
Sample RexSubquery(IN operator):-
LogicalFilter(condition=[IN($8, {
LogicalProject(EXPR$0=[$8])
LogicalFilter(condition=[=($7, 1)])
LogicalTableScan(table=[[foodmart, employee]])
})])
LogicalTableScan(table=[[foodmart, employee]])
On Thu, Jun 10, 2021 at 12:43 AM Julian Hyde <jhyde.apa...@gmail.com> wrote:
> I presume we’re talking about scalar sub-queries (e.g. sub-query in
> SELECT) and sub-queries with IN and EXISTS, as opposed to sub-queries in
> the FROM clause. The former are represented using RexSubQuery because the
> queries appear in scalar expressions.
>
> There are rules to expand RexSubQuery into relational operators. After
> those rules have been applied, then I’m sure that the Hep engine will be
> able to find them. I think that’s what Haisheng is referring to.
>
> But while those sub-queries are still wrapped in RexSubQuery, it’s
> possible that the Hep engine won’t find them. Because it will have to walk
> over every RexNode inside a Project, Filter or Join and if that RexNode is
> a RexSubQuery, traverse into it to apply the rules to the RelNodes inside.
> I don’t know whether that happens today. Someone should check. It’s a
> reasonable ask (but there might be unforeseen consequences if we enable it
> by default).
>
> Julian
>
>
>
> > On Jun 9, 2021, at 12:02 PM, Haisheng Yuan <hy...@apache.org> wrote:
> >
> > Did you include the subquery related rules in the HepPlanner?
> >
> > Haisheng
> >
> > On 2021/06/09 17:59:44, Krishnakant Agrawal <kk.agrawa...@gmail.com>
> wrote:
> >> Hi All,
> >>
> >> When running a HepOptimizer on top of a RelNode which has a subquery
> >> embedded in it, The Optimizer does not take the RelNode representing the
> >> subquery up for optimization.
> >>
> >> Is this by design, what's the correct way for the Subquery RelNode to
> be
> >> picked up for Optimization?
> >>
> >> If this is a bug, what is the conceptually correct way to go about
> fixing
> >> this?
> >>
> >> Thanks,
> >> KK
> >>
>
>
