[jira] [Created] (FLINK-4962) Improve exception information about operand type inference failed in UDF SQL validation

[Jark Wu (JIRA)]

Jark Wu created FLINK-4962:
------------------------------

             Summary: Improve exception information about operand type 
inference failed in UDF SQL validation
                 Key: FLINK-4962
                 URL: https://issues.apache.org/jira/browse/FLINK-4962
             Project: Flink
          Issue Type: Improvement
            Reporter: Jark Wu
            Priority: Minor


In the SQL validation phase, the custom scalar function 's operand types will 
be checked. If there is no corresponding signature , an exception will be 
thrown, but the exception message is unclear.

For example:

{code}
object Func13 extends ScalarFunction {
  def eval(a: Double): String = {
    s"$a"
  }
}

tEnv.registerFunction("Func13", Func13)
tEnv.sql("SELECT Func13(1.1) FROM MyTable")
{code}

and it throws 

{code}

Disconnected from the target VM, address: '127.0.0.1:63497', transport: 'socket'

org.apache.flink.api.table.ValidationException: SQL validation failed. Operand 
types of could not be inferred.

        at 
org.apache.flink.api.table.FlinkPlannerImpl.validate(FlinkPlannerImpl.scala:91)
        at 
org.apache.flink.api.table.expressions.utils.ExpressionTestBase.addSqlTestExpr(ExpressionTestBase.scala:140)
        at 
org.apache.flink.api.table.expressions.utils.ExpressionTestBase.testSqlApi(ExpressionTestBase.scala:208)
        at 
org.apache.flink.api.table.expressions.UserDefinedScalarFunctionTest.testResults(UserDefinedScalarFunctionTest.scala:114)
        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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
        at 
org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
        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:117)
        at 
com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
        at 
com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:262)
        at 
com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:84)
Caused by: org.apache.flink.api.table.ValidationException: Operand types of 
could not be inferred.
        at 
org.apache.flink.api.table.functions.utils.ScalarSqlFunction$$anon$2$$anonfun$2.apply(ScalarSqlFunction.scala:108)
        at 
org.apache.flink.api.table.functions.utils.ScalarSqlFunction$$anon$2$$anonfun$2.apply(ScalarSqlFunction.scala:108)
        at scala.Option.getOrElse(Option.scala:120)
        at 
org.apache.flink.api.table.functions.utils.ScalarSqlFunction$$anon$2.inferOperandTypes(ScalarSqlFunction.scala:108)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.inferUnknownTypes(SqlValidatorImpl.java:1659)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.expandSelectItem(SqlValidatorImpl.java:427)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelectList(SqlValidatorImpl.java:3549)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validateSelect(SqlValidatorImpl.java:3052)
        at 
org.apache.calcite.sql.validate.SelectNamespace.validateImpl(SelectNamespace.java:60)
        at 
org.apache.calcite.sql.validate.AbstractNamespace.validate(AbstractNamespace.java:86)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validateNamespace(SqlValidatorImpl.java:865)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validateQuery(SqlValidatorImpl.java:846)
        at org.apache.calcite.sql.SqlSelect.validate(SqlSelect.java:208)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validateScopedExpression(SqlValidatorImpl.java:821)
        at 
org.apache.calcite.sql.validate.SqlValidatorImpl.validate(SqlValidatorImpl.java:532)
        at 
org.apache.flink.api.table.FlinkPlannerImpl.validate(FlinkPlannerImpl.scala:87)
        ... 27 more
{code}

I hope it could express more information about the actual and expected operand 
types.

The {{ScalarSqlFunction.createOperandTypeInference}} should be touched.



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