[CALCITE-1907] Table function with 1 column gives ClassCastException

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.14.0
• Assignee: Julian Hyde
• Reporter: Julian Hyde
• Created: 27/Jul/17 22:49
• Updated: 02/Oct/17 14:30
• Resolved: 28/Jul/17 22:52

Description

If a table function has 1 column and is used under a Filter or Aggregate, the query gives ClassCastException when executed:

java.lang.RuntimeException: exception while executing [select *
from table("s"."fibonacci"())]

	at org.apache.calcite.test.CalciteAssert$AssertQuery.returns(CalciteAssert.java:1270)
	at org.apache.calcite.test.CalciteAssert$AssertQuery.returns(CalciteAssert.java:1249)
	at org.apache.calcite.test.TableFunctionTest.testUserDefinedTableFunction6(TableFunctionTest.java:381)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	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:51)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.lang.Long
	at org.apache.calcite.avatica.util.AbstractCursor$LongAccessor.getLong(AbstractCursor.java:550)
	at org.apache.calcite.avatica.AvaticaResultSet.getLong(AvaticaResultSet.java:277)
	at org.apache.calcite.test.TableFunctionTest$1.apply(TableFunctionTest.java:387)
	at org.apache.calcite.test.TableFunctionTest$1.apply(TableFunctionTest.java:382)
	at org.apache.calcite.test.CalciteAssert.assertQuery(CalciteAssert.java:533)
	at org.apache.calcite.test.CalciteAssert$AssertQuery.returns(CalciteAssert.java:1266)

The cause is a slight difference what the enumerable to iterable converter requires (arrays if there is more than one column, scalars is there is 1 column) and the specification of table functions (always return arrays).

Up until now we have been masking the problem by applying "slice" to the output of table functions. Which is fine if the output goes straight into the JDBC result set, but not fine if there are other operators, such as Filter or Aggregate, downstream.