[CALCITE-3394] Can not register implementation of a UDF with RexImpTable and use the same with RelBuilder

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.21.0
• Fix Version/s: 1.22.0
• Component/s: core
• Assignee: Unassigned
• Reporter: Vaishnavee Kulkarni
• Created: 09/Oct/19 14:02
• Updated: 28/May/21 10:09
• Resolved: 11/Oct/19 13:25

Description

I am trying to register a simple UDF that returns the length of input string. I can do this with prepareStatement approach -

public static class MyUdf1 {
   public Integer eval(String a) {
      return a.length();
   }
}

public void testUDF() {
final String strLenSql = "select STRLEN('SampleString') from emp";
ScalarFunction strLenFunction = ScalarFunctionImpl.create(MyUdf1.class, "eval");
calciteConnection.getRootSchema().add("STRLEN", strLenFunction);

ResultSet resultSet = calciteConnection.prepareStatement(strLenSql).executeQuery();
resultSet.next();
System.out.println(resultSet.getString(1));
}

 

When I try the similar steps with RelBuilder, I can successfully register the SqlOperator; but am unable to refer to the implementation of this operator. The builder refers to RexImpTable's maps for the function table implementation and there is no public/protected api exposed for these maps. 

SqlFunction length = new SqlFunction("STRLEN",
      SqlKind.OTHER_FUNCTION,
      ReturnTypes.INTEGER,
      null,
      OperandTypes.STRING,
      SqlFunctionCategory.USER_DEFINED_FUNCTION);

SqlStdOperatorTable sqlStdOperatorTable = SqlStdOperatorTable.instance();
sqlStdOperatorTable.register(length);

FrameworkConfig frameworkConfig = Frameworks.newConfigBuilder()
      .parserConfig(SqlParser.Config.DEFAULT)
      .defaultSchema(connection.getRootSchema().getSubSchema("SYSTEM"))
      .programs(Programs.sequence(Programs.ofRules(Programs.RULE_SET), Programs.CALC_PROGRAM))
      .operatorTable(sqlStdOperatorTable)
      .build();

final RelBuilder builder = RelBuilder.create(frameworkConfig);
RelNode udfRelNode = builder
      .scan("EMP")
      .project(builder.call(length,builder.literal("SampleString")))
      .build();

ResultSet resultSet = RelRunners.run(udfRelNode).executeQuery();

 

This code throws exception - 

Caused by: java.lang.RuntimeException: cannot translate call STRLEN($t3)Caused by: java.lang.RuntimeException: cannot translate call STRLEN($t3) at org.apache.calcite.adapter.enumerable.RexToLixTranslator.translateCall(RexToLixTranslator.java:756) at org.apache.calcite.adapter.enumerable.RexToLixTranslator.translate0(RexToLixTranslator.java:730) at org.apache.calcite.adapter.enumerable.RexToLixTranslator.translate(RexToLixTranslator.java:199) at org.apache.calcite.adapter.enumerable.RexToLixTranslator.translate0(RexToLixTranslator.java:684)

There are no junits that show this working with RelBuilder. Is it possible currently to register and use the udfs with RelBuilder?