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https://issues.apache.org/jira/browse/CALCITE-3394?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16949439#comment-16949439
]
Vaishnavee Kulkarni commented on CALCITE-3394:
----------------------------------------------
[~danny0405] Thank you for suggesting this approach! I will explore these
classes.
For now, I got this working by using `SqlUserDefinedFunction` and
`ScalarFunction` -
{code:java}
public static class MyUdf1 {
public Integer eval(String a) {
return a.length();
}
}
final String functionName = "STR_LEN";
final ScalarFunction udfLengthFunction =
ScalarFunctionImpl.create(Types.lookupMethod(MyUdf1.class, "eval",
String.class));
connection.getRootSchema().getSubSchema("SYSTEM").add(functionName,
udfLengthFunction);
FrameworkConfig frameworkConfig = getConfig();
SqlIdentifier udfLengthIdentifier = new
SqlIdentifier(Collections.singletonList(functionName), null, SqlParserPos.ZERO,
null);
final SqlOperator strLenOperator = new
SqlUserDefinedFunction(udfLengthIdentifier, ReturnTypes.INTEGER, null,
OperandTypes.STRING, null, udfLengthFunction);
final RelBuilder builder = RelBuilder.create(frameworkConfig);
RelNode udfRelNode = builder
.scan("EMP")
.project(builder.call(strLenOperator, builder.literal("SampleString")))
.build();
ResultSet set = RelRunners.run(udfRelNode).executeQuery();
{code}
> Can not register implementation of a UDF with RexImpTable and use the same
> with RelBuilder
> ------------------------------------------------------------------------------------------
>
> Key: CALCITE-3394
> URL: https://issues.apache.org/jira/browse/CALCITE-3394
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.21.0
> Reporter: Vaishnavee Kulkarni
> Priority: Major
>
> I am trying to register a simple UDF that returns the length of input string.
> I can do this with prepareStatement approach -
> {code:java}
> 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));
> }
> {code}
>
> 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.
> {code:java}
> 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();
> {code}
>
> This code throws exception -
> {code:java}
> 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)
> {code}
> There are no junits that show this working with _RelBuilder_. Is it possible
> currently to register and use the udfs with RelBuilder?
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