coral-spark/src/main/java/com/linkedin/coral/spark/CoralToSparkSqlCallConverter.java

@@ -15,8 +15,8 @@
 import com.linkedin.coral.common.transformers.OperatorRenameSqlCallTransformer;
 import com.linkedin.coral.common.transformers.SqlCallTransformers;
 import com.linkedin.coral.spark.containers.SparkUDFInfo;
-import com.linkedin.coral.spark.transformers.FallBackToLinkedInHiveUDFTransformer;
 import com.linkedin.coral.spark.transformers.FuzzyUnionGenericProjectTransformer;
+import com.linkedin.coral.spark.transformers.HiveUDFTransformer;
 import com.linkedin.coral.spark.transformers.TransportUDFTransformer;
 
 import static com.linkedin.coral.spark.transformers.TransportUDFTransformer.*;
@@ -27,7 +27,7 @@
  * which containing a list of {@link com.linkedin.coral.common.transformers.SqlCallTransformer} to traverse the hierarchy of a {@link org.apache.calcite.sql.SqlCall}
  * and converts the functions from Coral operator to Spark operator if it is required
  *
- * In this converter, we need to apply {@link TransportUDFTransformer} before {@link FallBackToLinkedInHiveUDFTransformer}
+ * In this converter, we need to apply {@link TransportUDFTransformer} before {@link HiveUDFTransformer}
  * because we should try to transform a UDF to an equivalent Transport UDF before falling back to LinkedIn Hive UDF.
  */
 public class CoralToSparkSqlCallConverter extends SqlShuttle {
@@ -154,7 +154,7 @@ public CoralToSparkSqlCallConverter(Set<SparkUDFInfo> sparkUDFInfos) {
         new OperatorRenameSqlCallTransformer(SqlStdOperatorTable.CARDINALITY, 1, "size"),
 
         // Fall back to the original Hive UDF defined in StaticHiveFunctionRegistry after failing to apply transformers above
-        new FallBackToLinkedInHiveUDFTransformer(sparkUDFInfos),
+        new HiveUDFTransformer(sparkUDFInfos),
 
         // Transform `generic_project` function
         new FuzzyUnionGenericProjectTransformer(sparkUDFInfos));

coral-spark/src/main/java/com/linkedin/coral/spark/transformers/FallBackToLinkedInHiveUDFTransformer.java → coral-spark/src/main/java/com/linkedin/coral/spark/transformers/HiveUDFTransformer.java

@@ -1,5 +1,5 @@
 /**
- * Copyright 2023 LinkedIn Corporation. All rights reserved.
+ * Copyright 2023-2024 LinkedIn Corporation. All rights reserved.
  * Licensed under the BSD-2 Clause license.
  * See LICENSE in the project root for license information.
  */
@@ -23,14 +23,12 @@
 
 
 /**
- * After failing to transform UDF with {@link TransportUDFTransformer},
- * we use this transformer to fall back to the original Hive UDF defined in
- * {@link com.linkedin.coral.hive.hive2rel.functions.StaticHiveFunctionRegistry}.
- * This is reasonable since Spark understands and has ability to run Hive UDF.
- * Check `CoralSparkTest#testFallBackToLinkedInHiveUDFTransformer()` for an example.
+ * This transformer converts the Hive UDF SqlCall name from the UDF class name (e.g., `com.linkedin.HiveUDF`)
+ * to the corresponding view-dependent UDF name in the view text. It also adds the UDF information to `sparkUDFInfos`.
+ * Refer to `CoralSparkTest#testHiveUDFTransformer()` for an example.
  */
-public class FallBackToLinkedInHiveUDFTransformer extends SqlCallTransformer {
-  private static final Logger LOG = LoggerFactory.getLogger(FallBackToLinkedInHiveUDFTransformer.class);
+public class HiveUDFTransformer extends SqlCallTransformer {
+  private static final Logger LOG = LoggerFactory.getLogger(HiveUDFTransformer.class);
 
   /**
    * Some LinkedIn UDFs get registered correctly in a SparkSession, and hence a DataFrame is successfully
@@ -46,7 +44,7 @@ public class FallBackToLinkedInHiveUDFTransformer extends SqlCallTransformer {
           "com.linkedin.coral.hive.hive2rel.CoralTestUnsupportedUDF");
   private final Set<SparkUDFInfo> sparkUDFInfos;
 
-  public FallBackToLinkedInHiveUDFTransformer(Set<SparkUDFInfo> sparkUDFInfos) {
+  public HiveUDFTransformer(Set<SparkUDFInfo> sparkUDFInfos) {
     this.sparkUDFInfos = sparkUDFInfos;
   }
 

coral-spark/src/test/java/com/linkedin/coral/spark/CoralSparkTest.java

@@ -137,7 +137,7 @@ public void testTransportUDFTransformer() {
   }
 
   @Test
-  public void testFallBackToLinkedInHiveUDFTransformer() {
+  public void testHiveUDFTransformer() {
     // Dali view foo_dali_udf2 contains a UDF not defined with OperatorBasedSqlCallTransformer or TransportUDFTransformer.
     // We need to fall back to the udf initially defined in HiveFunctionRegistry.
     // Then the function Name comes from Hive metastore in the format dbName_viewName_funcBaseName.