[Calcite] Volcano planner fails to optimize

[Zhangrucong]

Hi everyone,

I want to test calcite optimization of volcano planner with null cost factory. 
To avoid implementing some RelNodes and ConvertRules, I use BindableConvention 
trait set to transform converted RelNode. The QueryPlanner references to the 
implementation of SamzaSQL:

https://github.com/milinda/samza-sql/blob/master/samza-sql-planner/src/main/java/org/apache/samza/sql/planner/QueryPlanner.java

I replace the SamzaLogicalConvention.INSTANCE with the 
BindableConvention.INSTANCE and remove the HepPlanner optimization.

With the simple SQL test("select stream * from orders"), the volcano planner 
always complains following errors:

org.apache.calcite.plan.RelOptPlanner$CannotPlanException: Node 
[rel#11:Subset#2.BINDABLE.[]] could not be implemented; planner state:

Root: rel#11:Subset#2.BINDABLE.[]
Original rel:

Sets:
Set#0, type: RecordType(INTEGER orderId, INTEGER productId)
    rel#6:Subset#0.ENUMERABLE.[], best=rel#3, importance=0.7290000000000001
             rel#3:EnumerableTableScan.ENUMERABLE.[](table=[orders]), 
rowcount=100.0, cumulative cost={100.0 rows, 101.0 cpu, 0.0 io}
    rel#20:Subset#0.BINDABLE.[], best=null, importance=0.36450000000000005
Set#1, type: RecordType(INTEGER orderId, INTEGER productId)
    rel#8:Subset#1.NONE.[], best=null, importance=0.81
             
rel#7:LogicalProject.NONE.[](input=rel#6:Subset#0.ENUMERABLE.[],orderId=$0,productId=$1),
 rowcount=100.0, cumulative cost={inf}
    rel#17:Subset#1.BINDABLE.[], best=null, importance=0.405
             
rel#16:InterpretableConverter.BINDABLE.[](input=rel#8:Subset#1.NONE.[]), 
rowcount=100.0, cumulative cost={inf}
             
rel#21:BindableProject.BINDABLE.[](input=rel#20:Subset#0.BINDABLE.[],orderId=$0,productId=$1),
 rowcount=100.0, cumulative cost={inf}
Set#2, type: RecordType(INTEGER orderId, INTEGER productId)
    rel#10:Subset#2.NONE.[], best=null, importance=0.9
             rel#9:LogicalDelta.NONE.[](input=rel#8:Subset#1.NONE.[]), 
rowcount=100.0, cumulative cost={inf}
    rel#11:Subset#2.BINDABLE.[], best=null, importance=1.0
             
rel#12:AbstractConverter.BINDABLE.[](input=rel#10:Subset#2.NONE.[],convention=BINDABLE,sort=[]),
 rowcount=100.0, cumulative cost={inf}
             
rel#13:InterpretableConverter.BINDABLE.[](input=rel#10:Subset#2.NONE.[]), 
rowcount=100.0, cumulative cost={inf}

    at 
org.apache.calcite.plan.volcano.RelSubset$CheapestPlanReplacer.visit(RelSubset.java:443)
    at 
org.apache.calcite.plan.volcano.RelSubset.buildCheapestPlan(RelSubset.java:293)
    at 
org.apache.calcite.plan.volcano.VolcanoPlanner.findBestExp(VolcanoPlanner.java:841)
    at org.apache.calcite.tools.Programs$RuleSetProgram.run(Programs.java:334)
    at org.apache.calcite.prepare.PlannerImpl.transform(PlannerImpl.java:290)

I have no idea what to do with the runtime exceptions. Anything did I forget ? 
Or Did I misuse the BindableConvention trait set ?

Thanks.