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https://issues.apache.org/jira/browse/CALCITE-2018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16349476#comment-16349476
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Julian Hyde commented on CALCITE-2018:
--------------------------------------
I am still nervous about this change, because you have increased the lifetime
of {{RelMetadataQuery}}, and therefore there is more opportunity for the
metadata to go stale. I have thought of something that would help: can you add
some code that walks over the metadata and checks that it is valid? (E.g. check
that the cheapest rel in the subset really has lowest cost, and that the cached
selectivity of an expression is that same that would be calculated if we did it
again.) This method does not need be efficient - it would only be enabled in
debug mode - but it will give us confidence that the change propagation is
working correctly. If you do this I will commit.
> Queries failed with AssertionError: rel has lower cost than best cost of
> subset
> -------------------------------------------------------------------------------
>
> Key: CALCITE-2018
> URL: https://issues.apache.org/jira/browse/CALCITE-2018
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.13.0
> Reporter: Volodymyr Vysotskyi
> Assignee: Julian Hyde
> Priority: Critical
> Fix For: 1.16.0
>
>
> *Problem description*
> When rootLogger level is DEBUG, unit tests
> * MaterializationTest.testMaterializationSubstitution2
> * MaterializationTest.testJoinMaterializationUKFK8
> * MaterializationTest.testJoinMaterializationUKFK6
> * JdbcTest.testWhereNot
> unit tests are failed with error AssertionError: rel has lower cost than best
> cost of subset.
> Full stack trace for test
> {{MaterializationTest.testMaterializationSubstitution2}}:
> {noformat}
> java.lang.AssertionError: rel
> [rel#245:EnumerableUnion.ENUMERABLE.[](input#0=rel#246:Subset#5.ENUMERABLE.[],input#1=rel#239:Subset#6.ENUMERABLE.[0],all=true)]
> has lower cost {14.0 rows, 19.0 cpu, 0.0 io} than best cost {15.0 rows, 20.0
> cpu, 0.0 io} of subset [rel#243:Subset#7.ENUMERABLE.[]]
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.validate(VolcanoPlanner.java:906)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.register(VolcanoPlanner.java:866)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:883)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:101)
> at
> org.apache.calcite.rel.AbstractRelNode.onRegister(AbstractRelNode.java:336)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.registerImpl(VolcanoPlanner.java:1495)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.register(VolcanoPlanner.java:863)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:883)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.ensureRegistered(VolcanoPlanner.java:1766)
> at
> org.apache.calcite.plan.volcano.VolcanoRuleCall.transformTo(VolcanoRuleCall.java:135)
> at
> org.apache.calcite.plan.RelOptRuleCall.transformTo(RelOptRuleCall.java:234)
> at
> org.apache.calcite.rel.rules.FilterProjectTransposeRule.onMatch(FilterProjectTransposeRule.java:143)
> at
> org.apache.calcite.plan.volcano.VolcanoRuleCall.onMatch(VolcanoRuleCall.java:212)
> at
> org.apache.calcite.plan.volcano.VolcanoPlanner.findBestExp(VolcanoPlanner.java:650)
> at org.apache.calcite.tools.Programs$5.run(Programs.java:326)
> at
> org.apache.calcite.tools.Programs$SequenceProgram.run(Programs.java:387)
> at org.apache.calcite.prepare.Prepare.optimize(Prepare.java:187)
> at org.apache.calcite.prepare.Prepare.prepareSql(Prepare.java:318)
> at org.apache.calcite.prepare.Prepare.prepareSql(Prepare.java:229)
> at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepare2_(CalcitePrepareImpl.java:786)
> at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepare_(CalcitePrepareImpl.java:640)
> at
> org.apache.calcite.prepare.CalcitePrepareImpl.prepareSql(CalcitePrepareImpl.java:610)
> at org.apache.calcite.schema.Schemas.prepare(Schemas.java:346)
> at
> org.apache.calcite.materialize.MaterializationService$DefaultTableFactory.createTable(MaterializationService.java:374)
> at
> org.apache.calcite.materialize.MaterializationService.defineMaterialization(MaterializationService.java:137)
> at
> org.apache.calcite.materialize.MaterializationService.defineMaterialization(MaterializationService.java:99)
> at
> org.apache.calcite.schema.impl.MaterializedViewTable$MaterializedViewTableMacro.<init>(MaterializedViewTable.java:110)
> at
> org.apache.calcite.schema.impl.MaterializedViewTable$MaterializedViewTableMacro.<init>(MaterializedViewTable.java:100)
> at
> org.apache.calcite.schema.impl.MaterializedViewTable.create(MaterializedViewTable.java:81)
> at org.apache.calcite.model.ModelHandler.visit(ModelHandler.java:364)
> at
> org.apache.calcite.model.JsonMaterialization.accept(JsonMaterialization.java:42)
> at org.apache.calcite.model.JsonSchema.visitChildren(JsonSchema.java:98)
> at
> org.apache.calcite.model.JsonMapSchema.visitChildren(JsonMapSchema.java:48)
> at
> org.apache.calcite.model.ModelHandler.populateSchema(ModelHandler.java:257)
> at org.apache.calcite.model.ModelHandler.visit(ModelHandler.java:273)
> at
> org.apache.calcite.model.JsonCustomSchema.accept(JsonCustomSchema.java:45)
> at org.apache.calcite.model.ModelHandler.visit(ModelHandler.java:196)
> at org.apache.calcite.model.ModelHandler.<init>(ModelHandler.java:88)
> at org.apache.calcite.jdbc.Driver$1.onConnectionInit(Driver.java:104)
> at
> org.apache.calcite.avatica.UnregisteredDriver.connect(UnregisteredDriver.java:139)
> at java.sql.DriverManager.getConnection(DriverManager.java:571)
> at java.sql.DriverManager.getConnection(DriverManager.java:187)
> at
> org.apache.calcite.test.CalciteAssert$MapConnectionFactory.createConnection(CalciteAssert.java:1227)
> at
> org.apache.calcite.test.CalciteAssert$AssertQuery.createConnection(CalciteAssert.java:1266)
> at
> org.apache.calcite.test.CalciteAssert$AssertQuery.returns(CalciteAssert.java:1337)
> at
> org.apache.calcite.test.CalciteAssert$AssertQuery.returns(CalciteAssert.java:1320)
> at
> org.apache.calcite.test.CalciteAssert$AssertQuery.sameResultWithMaterializationsDisabled(CalciteAssert.java:1548)
> at
> org.apache.calcite.test.MaterializationTest.testMaterializationSubstitution2(MaterializationTest.java:2062)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
> at
> org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
> at
> org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
> at
> org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
> at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
> at
> org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
> at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
> at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
> at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
> at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
> at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
> at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
> at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
> at
> com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
> at
> com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
> at
> com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
> at
> com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
> {noformat}
> *Possible root cause*
> JaninoRelMetadataProvider caches metadata queries of {{RelSubset}} even when
> {{RelSubset.best}} value is not set.
> Actually not all RelNodes in {{RelSubset.set.rels}} have the same row count
> for some queries.
> When {{RelMetadataQuery.getRowCount(RelNode rel)}} method is called with
> {{RelSubset}} instance without best value, row count of {{RelSubset.set.rel}}
> is cached.
> After assigning best relNode, the {{RelMetadataQuery.getRowCount(RelNode
> rel)}} method returns old cached value if {{RelMetadataQuery}} instance still
> the same.
> This error appears when row count for best relNode is different from set.rel
> relNode.
> In the test {{MaterializationTest.testMaterializationSubstitution2}} row
> count of {{rel#237:LogicalFilter}} was cached and returned its value when
> relSubset had best {{rel#347:EnumerableFilter}}.
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