register a custom udf

[Guillaume Masse]

Hi All,

How can we register a custom udf? I found some solutions on Stackoverflow
but they are out of date (
https://stackoverflow.com/questions/44147819/adding-a-user-defined-function-to-calcite
)

So far what I have:

// top level class
class CustomUdf {
  def foo(in: Double): Double = in + 1
}

// somewhere else
val typeFactory = new JavaTypeFactoryImpl()

val root = CalciteSchema.createRootSchema(false)
root.plus().add("foo", ScalarFunctionImpl.create(classOf[CustomUdf], "foo"))

val catalogReader = new CalciteCatalogReader(
  root,
  Collections.emptyList(),
  typeFactory,
  CalciteConnectionConfig.DEFAULT
)

val operators =
  SqlLibraryOperatorTableFactory.INSTANCE.getOperatorTable(
    SqlLibrary.STANDARD,
    SqlLibrary.SPARK
  )

val sqlValidator = SqlValidatorUtil.newValidator(
  operators,
  catalogReader,
  typeFactory,
  SqlValidator.Config.DEFAULT
)

simple expression failed to
validate,org.apache.calcite.runtime.CalciteContextException: From line 1,
column 1 to line 1, column 22: No match found for function signature
toto(<NUMERIC>))

>From what I saw on Stackoverflow, it looks like I need to also add the
function to the operator table.

Thanks!
Guillaume Massé (马赛卫)