[SPARK-39384][SQL] Compile built-in linear regression aggregate functions for JDBC dialect

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/DB2IntegrationSuite.scala

@@ -106,4 +106,8 @@ class DB2IntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JDBCTest {
   testStddevSamp(true)
   testCovarPop()
   testCovarSamp()
+  testRegrIntercept()
+  testRegrSlope()
+  testRegrR2()
+  testRegrSXY()
 }

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/OracleIntegrationSuite.scala

@@ -111,4 +111,8 @@ class OracleIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JDBCTes
   testCovarPop()
   testCovarSamp()
   testCorr()
+  testRegrIntercept()
+  testRegrSlope()
+  testRegrR2()
+  testRegrSXY()
 }

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/PostgresIntegrationSuite.scala

@@ -104,4 +104,12 @@ class PostgresIntegrationSuite extends DockerJDBCIntegrationV2Suite with V2JDBCT
   testCovarSamp(true)
   testCorr()
   testCorr(true)
+  testRegrIntercept()
+  testRegrIntercept(true)
+  testRegrSlope()
+  testRegrSlope(true)
+  testRegrR2()
+  testRegrR2(true)
+  testRegrSXY()
+  testRegrSXY(true)
 }

connector/docker-integration-tests/src/test/scala/org/apache/spark/sql/jdbc/v2/V2JDBCTest.scala

@@ -523,4 +523,72 @@ private[v2] trait V2JDBCTest extends SharedSparkSession with DockerIntegrationFu
       assert(row(2).isNullAt(0))
     }
   }
+
+  protected def testRegrIntercept(isDistinct: Boolean = false): Unit = {
+    val distinct = if (isDistinct) "DISTINCT " else ""
+    test(s"scan with aggregate push-down: REGR_INTERCEPT with distinct: $isDistinct") {
+      val df = sql(
+        s"SELECT REGR_INTERCEPT(${distinct}bonus, bonus) FROM $catalogAndNamespace." +
+          s"${caseConvert("employee")} WHERE dept > 0 GROUP BY dept ORDER BY dept")
+      checkFilterPushed(df)
+      checkAggregateRemoved(df)
+      checkAggregatePushed(df, "REGR_INTERCEPT")
+      val row = df.collect()
+      assert(row.length === 3)
+      assert(row(0).getDouble(0) === 0d)
+      assert(row(1).getDouble(0) === 0d)
+      assert(row(2).isNullAt(0))
+    }
+  }
+
+  protected def testRegrSlope(isDistinct: Boolean = false): Unit = {
+    val distinct = if (isDistinct) "DISTINCT " else ""
+    test(s"scan with aggregate push-down: REGR_SLOPE with distinct: $isDistinct") {
+      val df = sql(
+        s"SELECT REGR_SLOPE(${distinct}bonus, bonus) FROM $catalogAndNamespace." +
+          s"${caseConvert("employee")} WHERE dept > 0 GROUP BY dept ORDER BY dept")
+      checkFilterPushed(df)
+      checkAggregateRemoved(df)
+      checkAggregatePushed(df, "REGR_SLOPE")
+      val row = df.collect()
+      assert(row.length === 3)
+      assert(row(0).getDouble(0) === 1d)
+      assert(row(1).getDouble(0) === 1d)
+      assert(row(2).isNullAt(0))
+    }
+  }
+
+  protected def testRegrR2(isDistinct: Boolean = false): Unit = {
+    val distinct = if (isDistinct) "DISTINCT " else ""
+    test(s"scan with aggregate push-down: REGR_R2 with distinct: $isDistinct") {
+      val df = sql(
+        s"SELECT REGR_R2(${distinct}bonus, bonus) FROM $catalogAndNamespace." +
+          s"${caseConvert("employee")} WHERE dept > 0 GROUP BY dept ORDER BY dept")
+      checkFilterPushed(df)
+      checkAggregateRemoved(df)
+      checkAggregatePushed(df, "REGR_R2")
+      val row = df.collect()
+      assert(row.length === 3)
+      assert(row(0).getDouble(0) === 1d)
+      assert(row(1).getDouble(0) === 1d)
+      assert(row(2).isNullAt(0))
+    }
+  }
+
+  protected def testRegrSXY(isDistinct: Boolean = false): Unit = {
+    val distinct = if (isDistinct) "DISTINCT " else ""
+    test(s"scan with aggregate push-down: REGR_SXY with distinct: $isDistinct") {
+      val df = sql(
+        s"SELECT REGR_SXY(${distinct}bonus, bonus) FROM $catalogAndNamespace." +
+          s"${caseConvert("employee")} WHERE dept > 0 GROUP BY dept ORDER BY dept")
+      checkFilterPushed(df)
+      checkAggregateRemoved(df)
+      checkAggregatePushed(df, "REGR_SXY")
+      val row = df.collect()
+      assert(row.length === 3)
+      assert(row(0).getDouble(0) === 20000d)
+      assert(row(1).getDouble(0) === 5000d)
+      assert(row(2).getDouble(0) === 0d)
+    }
+  }
 }

sql/core/src/main/scala/org/apache/spark/sql/jdbc/DB2Dialect.scala

@@ -32,15 +32,27 @@ private object DB2Dialect extends JdbcDialect {
   override def canHandle(url: String): Boolean =
     url.toLowerCase(Locale.ROOT).startsWith("jdbc:db2")
 
+  private val distinctUnsupportedAggregateFunctions =
+    Set("COVAR_POP", "COVAR_SAMP", "REGR_INTERCEPT", "REGR_R2", "REGR_SLOPE", "REGR_SXY")
+
   // See https://www.ibm.com/docs/en/db2/11.5?topic=functions-aggregate
   private val supportedAggregateFunctions = Set("MAX", "MIN", "SUM", "COUNT", "AVG",
-    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP", "COVAR_POP", "COVAR_SAMP")
+    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP") ++ distinctUnsupportedAggregateFunctions
   private val supportedFunctions = supportedAggregateFunctions
 
   override def isSupportedFunction(funcName: String): Boolean =
     supportedFunctions.contains(funcName)
 
   class DB2SQLBuilder extends JDBCSQLBuilder {
+    override def visitAggregateFunction(
+        funcName: String, isDistinct: Boolean, inputs: Array[String]): String =
+      if (isDistinct && distinctUnsupportedAggregateFunctions.contains(funcName)) {
+        throw new UnsupportedOperationException(s"${this.getClass.getSimpleName} does not " +
+          s"support aggregate function: $funcName with DISTINCT");
+      } else {
+        super.visitAggregateFunction(funcName, isDistinct, inputs)
+      }
+
     override def dialectFunctionName(funcName: String): String = funcName match {
       case "VAR_POP" => "VARIANCE"
       case "VAR_SAMP" => "VARIANCE_SAMP"

sql/core/src/main/scala/org/apache/spark/sql/jdbc/MySQLDialect.scala

@@ -22,13 +22,14 @@ import java.util
 import java.util.Locale
 
 import scala.collection.mutable.ArrayBuilder
+import scala.util.control.NonFatal
 
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.SQLConfHelper
 import org.apache.spark.sql.catalyst.analysis.{IndexAlreadyExistsException, NoSuchIndexException}
 import org.apache.spark.sql.connector.catalog.Identifier
 import org.apache.spark.sql.connector.catalog.index.TableIndex
-import org.apache.spark.sql.connector.expressions.{FieldReference, NamedReference}
+import org.apache.spark.sql.connector.expressions.{Expression, FieldReference, NamedReference}
 import org.apache.spark.sql.errors.QueryExecutionErrors
 import org.apache.spark.sql.execution.datasources.jdbc.{JDBCOptions, JdbcUtils}
 import org.apache.spark.sql.types.{BooleanType, DataType, FloatType, LongType, MetadataBuilder}
@@ -38,14 +39,39 @@ private case object MySQLDialect extends JdbcDialect with SQLConfHelper {
   override def canHandle(url : String): Boolean =
     url.toLowerCase(Locale.ROOT).startsWith("jdbc:mysql")
 
+  private val distinctUnsupportedAggregateFunctions =
+    Set("VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP")
+
   // See https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions.html
-  private val supportedAggregateFunctions = Set("MAX", "MIN", "SUM", "COUNT", "AVG",
-    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP")
+  private val supportedAggregateFunctions =
+    Set("MAX", "MIN", "SUM", "COUNT", "AVG") ++ distinctUnsupportedAggregateFunctions
   private val supportedFunctions = supportedAggregateFunctions
 
   override def isSupportedFunction(funcName: String): Boolean =
     supportedFunctions.contains(funcName)
 
+  class MySQLSQLBuilder extends JDBCSQLBuilder {
+    override def visitAggregateFunction(
+        funcName: String, isDistinct: Boolean, inputs: Array[String]): String =
+      if (isDistinct && distinctUnsupportedAggregateFunctions.contains(funcName)) {
+        throw new UnsupportedOperationException(s"${this.getClass.getSimpleName} does not " +
+          s"support aggregate function: $funcName with DISTINCT");
+      } else {
+        super.visitAggregateFunction(funcName, isDistinct, inputs)
+      }
+  }
+
+  override def compileExpression(expr: Expression): Option[String] = {
+    val mysqlSQLBuilder = new MySQLSQLBuilder()
+    try {
+      Some(mysqlSQLBuilder.build(expr))
+    } catch {
+      case NonFatal(e) =>
+        logWarning("Error occurs while compiling V2 expression", e)
+        None
+    }
+  }
+
   override def getCatalystType(
       sqlType: Int, typeName: String, size: Int, md: MetadataBuilder): Option[DataType] = {
     if (sqlType == Types.VARBINARY && typeName.equals("BIT") && size != 1) {

sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala

@@ -20,7 +20,10 @@ package org.apache.spark.sql.jdbc
 import java.sql.{Date, Timestamp, Types}
 import java.util.{Locale, TimeZone}
 
+import scala.util.control.NonFatal
+
 import org.apache.spark.sql.catalyst.util.DateTimeUtils
+import org.apache.spark.sql.connector.expressions.Expression
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.types._
 
@@ -33,16 +36,42 @@ private case object OracleDialect extends JdbcDialect {
   override def canHandle(url: String): Boolean =
     url.toLowerCase(Locale.ROOT).startsWith("jdbc:oracle")
 
+  private val distinctUnsupportedAggregateFunctions =
+    Set("VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP", "COVAR_POP", "COVAR_SAMP", "CORR",
+      "REGR_INTERCEPT", "REGR_R2", "REGR_SLOPE", "REGR_SXY")
+
   // scalastyle:off line.size.limit
   // https://docs.oracle.com/en/database/oracle/oracle-database/19/sqlrf/Aggregate-Functions.html#GUID-62BE676B-AF18-4E63-BD14-25206FEA0848
   // scalastyle:on line.size.limit
-  private val supportedAggregateFunctions = Set("MAX", "MIN", "SUM", "COUNT", "AVG",
-    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP", "COVAR_POP", "COVAR_SAMP", "CORR")
+  private val supportedAggregateFunctions =
+    Set("MAX", "MIN", "SUM", "COUNT", "AVG") ++ distinctUnsupportedAggregateFunctions
   private val supportedFunctions = supportedAggregateFunctions
 
   override def isSupportedFunction(funcName: String): Boolean =
     supportedFunctions.contains(funcName)
 
+  class OracleSQLBuilder extends JDBCSQLBuilder {
+    override def visitAggregateFunction(
+        funcName: String, isDistinct: Boolean, inputs: Array[String]): String =
+      if (isDistinct && distinctUnsupportedAggregateFunctions.contains(funcName)) {
+        throw new UnsupportedOperationException(s"${this.getClass.getSimpleName} does not " +
+          s"support aggregate function: $funcName with DISTINCT");
+      } else {
+        super.visitAggregateFunction(funcName, isDistinct, inputs)
+      }
+  }
+
+  override def compileExpression(expr: Expression): Option[String] = {
+    val oracleSQLBuilder = new OracleSQLBuilder()
+    try {
+      Some(oracleSQLBuilder.build(expr))
+    } catch {
+      case NonFatal(e) =>
+        logWarning("Error occurs while compiling V2 expression", e)
+        None
+    }
+  }
+
   private def supportTimeZoneTypes: Boolean = {
     val timeZone = DateTimeUtils.getTimeZone(SQLConf.get.sessionLocalTimeZone)
     // TODO: support timezone types when users are not using the JVM timezone, which

sql/core/src/main/scala/org/apache/spark/sql/jdbc/PostgresDialect.scala

@@ -38,7 +38,8 @@ private object PostgresDialect extends JdbcDialect with SQLConfHelper {
 
   // See https://www.postgresql.org/docs/8.4/functions-aggregate.html
   private val supportedAggregateFunctions = Set("MAX", "MIN", "SUM", "COUNT", "AVG",
-    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP", "COVAR_POP", "COVAR_SAMP", "CORR")
+    "VAR_POP", "VAR_SAMP", "STDDEV_POP", "STDDEV_SAMP", "COVAR_POP", "COVAR_SAMP", "CORR",
+    "REGR_INTERCEPT", "REGR_R2", "REGR_SLOPE", "REGR_SXY")
   private val supportedFunctions = supportedAggregateFunctions
 
   override def isSupportedFunction(funcName: String): Boolean =