godfrey he created FLINK-20899:
----------------------------------
Summary: encounter ClassCastException when calculating cost in
HepPlanner
Key: FLINK-20899
URL: https://issues.apache.org/jira/browse/FLINK-20899
Project: Flink
Issue Type: Bug
Reporter: godfrey he
Assignee: godfrey he
Fix For: 1.13.0
After TREACE level is enabled for Logger, we will encounter ClassCastException
when executing the following query:
{code:sql}
SELECT COUNT(*) FROM MyTable
{code}
the exception detail is:
{code:java}
java.lang.ClassCastException: org.apache.calcite.plan.RelOptCostImpl$Factory
cannot be cast to org.apache.flink.table.planner.plan.cost.FlinkCostFactory
at
org.apache.flink.table.planner.plan.nodes.physical.common.CommonPhysicalExchange.computeSelfCost(CommonPhysicalExchange.scala:53)
at
org.apache.flink.table.planner.plan.metadata.FlinkRelMdNonCumulativeCost.getNonCumulativeCost(FlinkRelMdNonCumulativeCost.scala:41)
at
GeneratedMetadataHandler_NonCumulativeCost.getNonCumulativeCost_$(Unknown
Source)
at
GeneratedMetadataHandler_NonCumulativeCost.getNonCumulativeCost(Unknown Source)
at
org.apache.calcite.rel.metadata.RelMetadataQuery.getNonCumulativeCost(RelMetadataQuery.java:288)
at
org.apache.flink.table.planner.plan.metadata.FlinkRelMdCumulativeCost.getCumulativeCost(FlinkRelMdCumulativeCost.scala:38)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost_$(Unknown
Source)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost(Unknown
Source)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost_$(Unknown
Source)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost(Unknown
Source)
at
org.apache.calcite.rel.metadata.RelMetadataQuery.getCumulativeCost(RelMetadataQuery.java:269)
at
org.apache.flink.table.planner.plan.metadata.FlinkRelMdCumulativeCost$$anonfun$getCumulativeCost$1.apply(FlinkRelMdCumulativeCost.scala:41)
at
org.apache.flink.table.planner.plan.metadata.FlinkRelMdCumulativeCost$$anonfun$getCumulativeCost$1.apply(FlinkRelMdCumulativeCost.scala:40)
at
scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:157)
at
scala.collection.TraversableOnce$$anonfun$foldLeft$1.apply(TraversableOnce.scala:157)
at scala.collection.Iterator$class.foreach(Iterator.scala:891)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
at
scala.collection.TraversableOnce$class.foldLeft(TraversableOnce.scala:157)
at scala.collection.AbstractTraversable.foldLeft(Traversable.scala:104)
at
org.apache.flink.table.planner.plan.metadata.FlinkRelMdCumulativeCost.getCumulativeCost(FlinkRelMdCumulativeCost.scala:39)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost_$(Unknown
Source)
at GeneratedMetadataHandler_CumulativeCost.getCumulativeCost(Unknown
Source)
at
org.apache.calcite.rel.metadata.RelMetadataQuery.getCumulativeCost(RelMetadataQuery.java:269)
at
org.apache.calcite.plan.AbstractRelOptPlanner.getCost(AbstractRelOptPlanner.java:247)
at
org.apache.calcite.plan.hep.HepPlanner.dumpGraph(HepPlanner.java:1023)
at org.apache.calcite.plan.hep.HepPlanner.setRoot(HepPlanner.java:159)
at
org.apache.flink.table.planner.plan.optimize.program.FlinkHepProgram.optimize(FlinkHepProgram.scala:60)
{code}
The reason is the HepPlanner will calcite the cost of the optimized plan when
TRACE is enabled, while the cost factory in hep planner is
{{RelOptCostImpl.Factory}} not the sub-class of FlinkCostFactory.
The solution is we should create HepPlanner with the cost factory in the
RelOptCluster.
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