Thanks for looking more into this Mark. Passing RelNodes from one planner to another is not a good idea. Ideally this should be possible but I guess it requires CALCITE-1536 [1] to be solved.
Another way to avoid problems like the one you observed is to copy RelNodes from one cluster to another [2]. Best, Stamatis [1] https://issues.apache.org/jira/browse/CALCITE-1536 [2] https://issues.apache.org/jira/browse/CALCITE-1681 On Mon, May 6, 2019 at 12:02 PM Mark Pasterkamp < [email protected]> wrote: > I think I found the origin of the exception. > To convert a single query to a rel node I am using the PlannerImp provided > by Frameworks.getPlanner(). > This planner provides a VolcanoPlanner to the relnode clusters. > When calling the HepPlanner.findBestExp() it will eventually call > the applyTransformationResults which will compute a cost using the > rel.getCluster().getPlanner() (which is a VolcanoPlanner). > > Mark > > On Fri, 3 May 2019 at 19:56, Mark Pasterkamp <[email protected] > > > wrote: > > > I did not know this is how it works, I just copied the example above. > > Would there be an easy way to create a RelNode containg a tablescan over > > the materialized view "mv"? > > Trying to create one using for instance a relbuilder gives a calcite > > exception. > > Otherwise I might just look for another test file in which I can get > > access to the schema and use the materiaqlizationservice. > > > > Mark > > > > On Fri, 3 May 2019 at 18:35, Jesus Camacho Rodriguez > > <[email protected]> wrote: > > > >> bq . Since we are talking about materialized views, I think in most > cases > >> tableRel should be simply a LogicalTableScan. > >> > >> Stamatis is correct about this, I had not realized tableRel == queryRel > >> in > >> your sample code. > >> > >> Thanks, > >> Jesús > >> > >> On Fri, May 3, 2019 at 6:12 AM Stamatis Zampetakis <[email protected]> > >> wrote: > >> > >> > I think the main problem comes from the fact that tableRel == queryRel > >> in > >> > the test case you provided. > >> > Defining the materialized view like that basically says that when you > >> find > >> > a part of the query that satisfies queryRel replace it with itself. > >> > In conjunction with the rule that is used, which allows partial > >> rewritings > >> > using union, you end up with a rule that matches infinite number of > >> times. > >> > Since we are talking about materialized views, I think in most cases > >> > tableRel should be simply a LogicalTableScan. > >> > The idea is that expression represented by queryRel is materialized > >> into a > >> > table so in order to retrieve the results we only need to scan the > >> table. > >> > > >> > Regarding the "if (true)" statements that you observed, most likely > they > >> > were introduced as release toggles [1]. > >> > However, since the last commit was in 2013 I think by now it is safe > to > >> > refactor that part and remove dead code. > >> > > >> > [1] https://www.martinfowler.com/articles/feature-toggles.html > >> > > >> > Best, > >> > Stamatis > >> > > >> > On Fri, May 3, 2019 at 12:50 PM Mark Pasterkamp < > >> > [email protected]> wrote: > >> > > >> > > Dear Jesus, > >> > > > >> > > I think your intuition in this regard is correct. > >> > > After executing the main program in the HepPlanner the resulting > plan > >> > > contains a lot of circular references. > >> > > Changing the matching order does not influence this behaviour. > >> > > > >> > > > >> > > Mark > >> > > > >> > > On Thu, 2 May 2019 at 22:14, Jesus Camacho Rodriguez > >> > > <[email protected]> wrote: > >> > > > >> > > > Mark, > >> > > > > >> > > > I have an intuition that this happens because the rule creates a > >> > > partially > >> > > > contained rewriting with a union, where one side contains a scan > >> over > >> > the > >> > > > materialized view and the other side contains the query itself > with > >> a > >> > > > filter on top excluding the data that is coming from the > >> materialized > >> > > view. > >> > > > Then the rule is triggered on the plan representing the original > >> query > >> > > > again and the process is repeated. Have you tried changing the > >> matching > >> > > > order for your hep program? > >> > > > > >> > > > Thanks, > >> > > > Jesús > >> > > > > >> > > > On Thu, May 2, 2019 at 8:53 AM Mark Pasterkamp < > >> > > > [email protected]> > >> > > > wrote: > >> > > > > >> > > > > Hi Stamatis, > >> > > > > > >> > > > > I have tried to recreate the issue but I have not been able to > do > >> > > that. I > >> > > > > was however able to create a new exception which I don't quite > >> > > > understand. > >> > > > > The error happened when calcite was creating a union rewriting > >> using > >> > > > > materialized views. But trying to recreate this situation gave > me > >> > > another > >> > > > > interesting one. > >> > > > > This time, the planner rewrites one of the children nodes into > >> > itself I > >> > > > > would assume which causes a stack overflow. The method itself > can > >> be > >> > > > found > >> > > > > here: > >> > > > > > >> > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > https://github.com/mpasterkamp/calcite/blob/768b7928dbde5f6f9775a1119e7466d8eafafb4b/core/src/test/java/org/apache/calcite/test/HepPlannerTest.java#L312 > >> > > > > > >> > > > > Perhaps I am doing something wrong, perhaps not? I am not > >> > knowledgeable > >> > > > > enough about this to understand why this is happening. Wish I > >> could > >> > > help > >> > > > > more for that. > >> > > > > > >> > > > > Also, while investigating this issue I found another interesting > >> > > artifact > >> > > > > in de source code of the VolcanoCost. A lot of methods in this > >> class > >> > > have > >> > > > > an "if (true)"-statement like here: > >> > > > > > >> > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > https://github.com/apache/calcite/blob/4b4d8037c5073e4eb5702b12bc4ecade31476616/core/src/main/java/org/apache/calcite/plan/volcano/VolcanoCost.java#L100 > >> > > > > > >> > > > > Now I was just curious, is there any reason for this to be there > >> that > >> > > you > >> > > > > know of? > >> > > > > > >> > > > > Thank you for responding and congratulations for your recent > >> > > promotions. > >> > > > > > >> > > > > > >> > > > > With kind regards, > >> > > > > > >> > > > > Mark > >> > > > > > >> > > > > > >> > > > > On Thu, 2 May 2019 at 14:58, Stamatis Zampetakis < > >> [email protected]> > >> > > > > wrote: > >> > > > > > >> > > > > > Said like that it looks like a bug. > >> > > > > > > >> > > > > > I think the best would be to reproduce the exception as a unit > >> test > >> > > in > >> > > > > > HepPlannerTest [1], RelOptRulesTest [2], or PlannerTest [3] so > >> that > >> > > we > >> > > > > > could understand better the use case. > >> > > > > > > >> > > > > > [1] > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/test/HepPlannerTest.java > >> > > > > > [2] > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java > >> > > > > > [3] > >> > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > https://github.com/apache/calcite/blob/master/core/src/test/java/org/apache/calcite/tools/PlannerTest.java > >> > > > > > > >> > > > > > On Thu, May 2, 2019 at 7:56 AM Mark Pasterkamp < > >> > > > > > [email protected]> > >> > > > > > wrote: > >> > > > > > > >> > > > > > > I don't, I would assume that the HepPlanner.findBestExp() > >> > > calculates > >> > > > > the > >> > > > > > > cost somewhere down the line > >> > > > > > > > >> > > > > > > On Thu, May 2, 2019, 03:31 Yuzhao Chen < > [email protected]> > >> > > wrote: > >> > > > > > > > >> > > > > > > > Why you care about cost when use HepPlanner ? The > >> HepPlanner is > >> > > > aimed > >> > > > > > for > >> > > > > > > > some deterministic planning rules, we usually do not need > >> cost > >> > in > >> > > > > Hep. > >> > > > > > > Some > >> > > > > > > > exceptions like Join reorder may need a cost. > >> > > > > > > > > >> > > > > > > > What kind of planning promotion you did ? I'm kind of > >> curious > >> > > about > >> > > > > it. > >> > > > > > > > > >> > > > > > > > Best, > >> > > > > > > > Danny Chan > >> > > > > > > > 在 2019年5月1日 +0800 PM9:27，Mark Pasterkamp < > >> > > > > [email protected] > >> > > > > > > > >，写道： > >> > > > > > > > > Dear all, > >> > > > > > > > > > >> > > > > > > > > While playing around with the HepPlanner I ran into an > >> issue > >> > > > where > >> > > > > > the > >> > > > > > > > > planner wants to rewrite a query with a union rewrite. > >> When > >> > the > >> > > > > > > > > RelMetaDataQuery computes the cost, the cost instance > is a > >> > > > > > VolcanoCost. > >> > > > > > > > > Then when it tries to calculate the cost of one of the > >> > union's > >> > > > > > operands > >> > > > > > > > it > >> > > > > > > > > is a RelCostImpl which results in the > ClassCastException. > >> > > > > > > > > > >> > > > > > > > > How would I go about solving this issue? As far as my > >> > knowledge > >> > > > > > goes, I > >> > > > > > > > am > >> > > > > > > > > not able to change the costhandler of the > >> RelMetaDataQuery. > >> > > > Another > >> > > > > > > > > approach I could see is removing the cast in the > >> VolcanoCost > >> > > > class, > >> > > > > > > but I > >> > > > > > > > > would hope I do not have to do that. > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > With kind regards, > >> > > > > > > > > > >> > > > > > > > > Mark > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > > >
