[GLUTEN-7116] [CH] support outer explode

backends-clickhouse/src/main/scala/org/apache/gluten/backendsapi/clickhouse/CHSparkPlanExecApi.scala

@@ -925,4 +925,12 @@ class CHSparkPlanExecApi extends SparkPlanExecApi with Logging {
       limit,
       mode,
       child)
+
+  override def genStringSplitTransformer(
+      substraitExprName: String,
+      srcExpr: ExpressionTransformer,
+      regexExpr: ExpressionTransformer,
+      limitExpr: ExpressionTransformer,
+      original: StringSplit): ExpressionTransformer =
+    CHStringSplitTransformer(substraitExprName, Seq(srcExpr, regexExpr, limitExpr), original)
 }

backends-clickhouse/src/main/scala/org/apache/gluten/execution/CHGenerateExecTransformer.scala

@@ -76,6 +76,7 @@ case class CHGenerateExecTransformer(
         inputRel,
         generatorNode,
         requiredChildOutputNodes.asJava,
+        outer,
         context,
         context.nextOperatorId(this.nodeName))
     } else {
@@ -84,6 +85,7 @@ case class CHGenerateExecTransformer(
         generatorNode,
         requiredChildOutputNodes.asJava,
         getExtensionNodeForValidation,
+        outer,
         context,
         context.nextOperatorId(this.nodeName))
     }

backends-clickhouse/src/main/scala/org/apache/gluten/expression/CHExpressionTransformer.scala

@@ -243,3 +243,12 @@ case class GetArrayItemTransformer(
       ConverterUtils.getTypeNode(getArrayItem.dataType, getArrayItem.nullable))
   }
 }
+case class CHStringSplitTransformer(
+    substraitExprName: String,
+    children: Seq[ExpressionTransformer],
+    original: Expression,
+    override val dataType: DataType = ArrayType(StringType, containsNull = true))
+  extends ExpressionTransformer {
+  // In Spark: split return Array(String), while Array is nullable
+  // In CH: splitByXXX return Array(Nullable(String))
+}

backends-velox/src/main/scala/org/apache/gluten/execution/GenerateExecTransformer.scala

@@ -91,6 +91,7 @@ case class GenerateExecTransformer(
       generatorNode,
       requiredChildOutputNodes.asJava,
       getExtensionNode(validation),
+      outer,
       context,
       operatorId)
   }

cpp-ch/local-engine/Parser/RelParsers/ProjectRelParser.cpp

@@ -199,7 +199,7 @@ ProjectRelParser::parseGenerate(DB::QueryPlanPtr query_plan, const substrait::Re
 
         /// ARRAY JOIN
         NameSet array_joined_columns{findArrayJoinNode(splitted_actions_dags.array_join)->result_name};
-        auto array_join_action = std::make_shared<ArrayJoinAction>(array_joined_columns, false, getContext());
+        auto array_join_action = std::make_shared<ArrayJoinAction>(array_joined_columns, generate_rel.outer(), getContext());
         auto array_join_step = std::make_unique<ArrayJoinStep>(query_plan->getCurrentDataStream(), array_join_action);
         array_join_step->setStepDescription("ARRAY JOIN In Generate");
         steps.emplace_back(array_join_step.get());

gluten-substrait/src/main/java/org/apache/gluten/substrait/rel/GenerateRelNode.java

@@ -31,20 +31,24 @@ public class GenerateRelNode implements RelNode, Serializable {
   private final ExpressionNode generator;
   private final List<ExpressionNode> childOutput;
   private final AdvancedExtensionNode extensionNode;
+  private final boolean outer;
 
-  GenerateRelNode(RelNode input, ExpressionNode generator, List<ExpressionNode> childOutput) {
-    this(input, generator, childOutput, null);
+  GenerateRelNode(
+      RelNode input, ExpressionNode generator, List<ExpressionNode> childOutput, boolean outer) {
+    this(input, generator, childOutput, null, outer);
   }
 
   GenerateRelNode(
       RelNode input,
       ExpressionNode generator,
       List<ExpressionNode> childOutput,
-      AdvancedExtensionNode extensionNode) {
+      AdvancedExtensionNode extensionNode,
+      boolean outer) {
     this.input = input;
     this.generator = generator;
     this.childOutput = childOutput;
     this.extensionNode = extensionNode;
+    this.outer = outer;
   }
 
   @Override
@@ -67,6 +71,8 @@ public Rel toProtobuf() {
       generateRelBuilder.addChildOutput(node.toProtobuf());
     }
 
+    generateRelBuilder.setOuter(outer);
+
     if (extensionNode != null) {
       generateRelBuilder.setAdvancedExtension(extensionNode.toProtobuf());
     }

gluten-substrait/src/main/java/org/apache/gluten/substrait/rel/RelBuilder.java

@@ -299,20 +299,22 @@ public static RelNode makeGenerateRel(
       RelNode input,
       ExpressionNode generator,
       List<ExpressionNode> childOutput,
+      boolean outer,
       SubstraitContext context,
       Long operatorId) {
     context.registerRelToOperator(operatorId);
-    return new GenerateRelNode(input, generator, childOutput);
+    return new GenerateRelNode(input, generator, childOutput, outer);
   }
 
   public static RelNode makeGenerateRel(
       RelNode input,
       ExpressionNode generator,
       List<ExpressionNode> childOutput,
       AdvancedExtensionNode extensionNode,
+      boolean outer,
       SubstraitContext context,
       Long operatorId) {
     context.registerRelToOperator(operatorId);
-    return new GenerateRelNode(input, generator, childOutput, extensionNode);
+    return new GenerateRelNode(input, generator, childOutput, extensionNode, outer);
   }
 }

gluten-substrait/src/main/scala/org/apache/gluten/backendsapi/SparkPlanExecApi.scala

@@ -693,4 +693,12 @@ trait SparkPlanExecApi {
       attributeSeq: Seq[Attribute]): ExpressionTransformer = {
     HiveUDFTransformer.replaceWithExpressionTransformer(expr, attributeSeq)
   }
+
+  def genStringSplitTransformer(
+      substraitExprName: String,
+      srcExpr: ExpressionTransformer,
+      regexExpr: ExpressionTransformer,
+      limitExpr: ExpressionTransformer,
+      original: StringSplit): ExpressionTransformer =
+    GenericExpressionTransformer(substraitExprName, Seq(srcExpr, regexExpr, limitExpr), original)
 }

gluten-substrait/src/main/scala/org/apache/gluten/expression/ExpressionConverter.scala

@@ -689,6 +689,14 @@ object ExpressionConverter extends SQLConfHelper with Logging {
           timeAdd.children,
           timeAdd
         )
+      case ss: StringSplit =>
+        BackendsApiManager.getSparkPlanExecApiInstance.genStringSplitTransformer(
+          substraitExprName,
+          replaceWithExpressionTransformer0(ss.str, attributeSeq, expressionsMap),
+          replaceWithExpressionTransformer0(ss.regex, attributeSeq, expressionsMap),
+          replaceWithExpressionTransformer0(ss.limit, attributeSeq, expressionsMap),
+          ss
+        )
       case expr =>
         GenericExpressionTransformer(
           substraitExprName,

gluten-ut/spark32/src/test/scala/org/apache/spark/sql/hive/execution/GlutenHiveSQLQueryCHSuite.scala

@@ -105,4 +105,21 @@ class GlutenHiveSQLQueryCHSuite extends GlutenHiveSQLQuerySuiteBase {
       purge = false)
   }
 
+  testGluten("GLUTEN-7116: Support outer explode") {
+    sql("create table if not exists test_7116 (id int, name string)")
+    sql("insert into test_7116 values (1, 'a,b'), (2, null), (null, 'c,d'), (3, '')")
+    val query =
+      """
+        |select id, col_name
+        |from test_7116 lateral view outer explode(split(name, ',')) as col_name
+        |""".stripMargin
+    val df = sql(query)
+    checkAnswer(
+      df,
+      Seq(Row(1, "a"), Row(1, "b"), Row(2, null), Row(null, "c"), Row(null, "d"), Row(3, "")))
+    spark.sessionState.catalog.dropTable(
+      TableIdentifier("test_7116"),
+      ignoreIfNotExists = true,
+      purge = false)
+  }
 }

gluten-ut/spark33/src/test/scala/org/apache/spark/sql/hive/execution/GlutenHiveSQLQueryCHSuite.scala

@@ -105,4 +105,21 @@ class GlutenHiveSQLQueryCHSuite extends GlutenHiveSQLQuerySuiteBase {
       purge = false)
   }
 
+  testGluten("GLUTEN-7116: Support outer explode") {
+    sql("create table if not exists test_7116 (id int, name string)")
+    sql("insert into test_7116 values (1, 'a,b'), (2, null), (null, 'c,d'), (3, '')")
+    val query =
+      """
+        |select id, col_name
+        |from test_7116 lateral view outer explode(split(name, ',')) as col_name
+        |""".stripMargin
+    val df = sql(query)
+    checkAnswer(
+      df,
+      Seq(Row(1, "a"), Row(1, "b"), Row(2, null), Row(null, "c"), Row(null, "d"), Row(3, "")))
+    spark.sessionState.catalog.dropTable(
+      TableIdentifier("test_7116"),
+      ignoreIfNotExists = true,
+      purge = false)
+  }
 }

gluten-ut/spark34/src/test/scala/org/apache/spark/sql/hive/execution/GlutenHiveSQLQueryCHSuite.scala

@@ -105,4 +105,21 @@ class GlutenHiveSQLQueryCHSuite extends GlutenHiveSQLQuerySuiteBase {
       purge = false)
   }
 
+  testGluten("GLUTEN-7116: Support outer explode") {
+    sql("create table if not exists test_7116 (id int, name string)")
+    sql("insert into test_7116 values (1, 'a,b'), (2, null), (null, 'c,d'), (3, '')")
+    val query =
+      """
+        |select id, col_name
+        |from test_7116 lateral view outer explode(split(name, ',')) as col_name
+        |""".stripMargin
+    val df = sql(query)
+    checkAnswer(
+      df,
+      Seq(Row(1, "a"), Row(1, "b"), Row(2, null), Row(null, "c"), Row(null, "d"), Row(3, "")))
+    spark.sessionState.catalog.dropTable(
+      TableIdentifier("test_7116"),
+      ignoreIfNotExists = true,
+      purge = false)
+  }
 }

gluten-ut/spark35/src/test/scala/org/apache/spark/sql/hive/execution/GlutenHiveSQLQueryCHSuite.scala

@@ -105,4 +105,21 @@ class GlutenHiveSQLQueryCHSuite extends GlutenHiveSQLQuerySuiteBase {
       purge = false)
   }
 
+  testGluten("GLUTEN-7116: Support outer explode") {
+    sql("create table if not exists test_7116 (id int, name string)")
+    sql("insert into test_7116 values (1, 'a,b'), (2, null), (null, 'c,d'), (3, '')")
+    val query =
+      """
+        |select id, col_name
+        |from test_7116 lateral view outer explode(split(name, ',')) as col_name
+        |""".stripMargin
+    val df = sql(query)
+    checkAnswer(
+      df,
+      Seq(Row(1, "a"), Row(1, "b"), Row(2, null), Row(null, "c"), Row(null, "d"), Row(3, "")))
+    spark.sessionState.catalog.dropTable(
+      TableIdentifier("test_7116"),
+      ignoreIfNotExists = true,
+      purge = false)
+  }
 }