[SPARK-37483][SQL] Support push down top N to JDBC data source V2

### What changes were proposed in this pull request? Currently, Spark supports push down limit to data source. However, in the user's scenario, limit must have the premise of order by. Because limit and order by are more valuable together. On the other hand, push down top N(same as order by ... limit N) outputs the data with basic order to Spark sort, the the sort of Spark may have some performance improvement. ### Why are the changes needed? 1. push down top N is very useful for users scenario. 2. push down top N could improves the performance of sort. ### Does this PR introduce _any_ user-facing change? 'No'. Just change the physical execute. ### How was this patch tested? New tests. Closes apache#34918 from beliefer/SPARK-37483. Authored-by: Jiaan Geng <[email protected]> Signed-off-by: Wenchen Fan <[email protected]>
chenzhx · Feb 22, 2022 · 3166107 · 3166107
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diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownLimit.java b/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownLimit.java
@@ -20,7 +20,7 @@
 import org.apache.spark.annotation.Evolving;
 
 /**
- * A mix-in interface for {@link Scan}. Data sources can implement this interface to
+ * A mix-in interface for {@link ScanBuilder}. Data sources can implement this interface to
  * push down LIMIT. Please note that the combination of LIMIT with other operations
  * such as AGGREGATE, GROUP BY, SORT BY, CLUSTER BY, DISTRIBUTE BY, etc. is NOT pushed down.
  *

diff --git a/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownTopN.java b/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownTopN.java
@@ -0,0 +1,38 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.connector.read;
+
+import org.apache.spark.annotation.Evolving;
+import org.apache.spark.sql.connector.expressions.SortOrder;
+
+/**
+ * A mix-in interface for {@link ScanBuilder}. Data sources can implement this interface to
+ * push down top N(query with ORDER BY ... LIMIT n). Please note that the combination of top N
+ * with other operations such as AGGREGATE, GROUP BY, CLUSTER BY, DISTRIBUTE BY, etc.
+ * is NOT pushed down.
+ *
+ * @since 3.3.0
+ */
+@Evolving
+public interface SupportsPushDownTopN extends ScanBuilder {
+
+    /**
+     * Pushes down top N to the data source.
+     */
+    boolean pushTopN(SortOrder[] orders, int limit);
+}
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/DataSourceScanExec.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/DataSourceScanExec.scala
@@ -142,13 +142,23 @@ case class RowDataSourceScanExec(
       handledFilters
     }
 
+    val topNOrLimitInfo =
+      if (pushedDownOperators.limit.isDefined && pushedDownOperators.sortValues.nonEmpty) {
+        val pushedTopN =
+          s"ORDER BY ${seqToString(pushedDownOperators.sortValues.map(_.describe()))}" +
+          s" LIMIT ${pushedDownOperators.limit.get}"
+        Some("pushedTopN" -> pushedTopN)
+    } else {
+      pushedDownOperators.limit.map(value => "PushedLimit" -> s"LIMIT $value")
+    }
+
     Map(
       "ReadSchema" -> requiredSchema.catalogString,
       "PushedFilters" -> seqToString(markedFilters.toSeq)) ++
       pushedDownOperators.aggregation.fold(Map[String, String]()) { v =>
         Map("PushedAggregates" -> seqToString(v.aggregateExpressions),
           "PushedGroupByColumns" -> seqToString(v.groupByColumns))} ++
-      pushedDownOperators.limit.map(value => "PushedLimit" -> s"LIMIT $value") ++
+      topNOrLimitInfo ++
       pushedDownOperators.sample.map(v => "PushedSample" ->
         s"SAMPLE (${(v.upperBound - v.lowerBound) * 100}) ${v.withReplacement} SEED(${v.seed})"
       )

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSourceStrategy.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSourceStrategy.scala
@@ -40,7 +40,7 @@ import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.catalyst.streaming.StreamingRelationV2
 import org.apache.spark.sql.connector.catalog.SupportsRead
 import org.apache.spark.sql.connector.catalog.TableCapability._
-import org.apache.spark.sql.connector.expressions.FieldReference
+import org.apache.spark.sql.connector.expressions.{FieldReference, NullOrdering, SortDirection, SortOrder => SortOrderV2, SortValue}
 import org.apache.spark.sql.connector.expressions.aggregate.{AggregateFunc, Count, CountStar, Max, Min, Sum}
 import org.apache.spark.sql.errors.QueryCompilationErrors
 import org.apache.spark.sql.execution.{InSubqueryExec, RowDataSourceScanExec, SparkPlan}
@@ -336,7 +336,7 @@ object DataSourceStrategy
         l.output.toStructType,
         Set.empty,
         Set.empty,
-        PushedDownOperators(None, None, None),
+        PushedDownOperators(None, None, None, Seq.empty),
         toCatalystRDD(l, baseRelation.buildScan()),
         baseRelation,
         None) :: Nil
@@ -410,7 +410,7 @@ object DataSourceStrategy
         requestedColumns.toStructType,
         pushedFilters.toSet,
         handledFilters,
-        PushedDownOperators(None, None, None),
+        PushedDownOperators(None, None, None, Seq.empty),
         scanBuilder(requestedColumns, candidatePredicates, pushedFilters),
         relation.relation,
         relation.catalogTable.map(_.identifier))
@@ -433,7 +433,7 @@ object DataSourceStrategy
         requestedColumns.toStructType,
         pushedFilters.toSet,
         handledFilters,
-        PushedDownOperators(None, None, None),
+        PushedDownOperators(None, None, None, Seq.empty),
         scanBuilder(requestedColumns, candidatePredicates, pushedFilters),
         relation.relation,
         relation.catalogTable.map(_.identifier))
@@ -723,6 +723,24 @@ object DataSourceStrategy
     }
   }
 
+  protected[sql] def translateSortOrders(sortOrders: Seq[SortOrder]): Seq[SortOrderV2] = {
+    def translateOortOrder(sortOrder: SortOrder): Option[SortOrderV2] = sortOrder match {
+      case SortOrder(PushableColumnWithoutNestedColumn(name), directionV1, nullOrderingV1, _) =>
+        val directionV2 = directionV1 match {
+          case Ascending => SortDirection.ASCENDING
+          case Descending => SortDirection.DESCENDING
+        }
+        val nullOrderingV2 = nullOrderingV1 match {
+          case NullsFirst => NullOrdering.NULLS_FIRST
+          case NullsLast => NullOrdering.NULLS_LAST
+        }
+        Some(SortValue(FieldReference(name), directionV2, nullOrderingV2))
+      case _ => None
+    }
+
+    sortOrders.flatMap(translateOortOrder)
+  }
+
   /**
    * Convert RDD of Row into RDD of InternalRow with objects in catalyst types
    */

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRDD.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRDD.scala
@@ -25,6 +25,7 @@ import org.apache.spark.{InterruptibleIterator, Partition, SparkContext, TaskCon
 import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.InternalRow
+import org.apache.spark.sql.connector.expressions.SortOrder
 import org.apache.spark.sql.execution.datasources.v2.TableSampleInfo
 import org.apache.spark.sql.jdbc.{JdbcDialect, JdbcDialects}
 import org.apache.spark.sql.sources._
@@ -151,12 +152,14 @@ object JDBCRDD extends Logging {
    * @param options - JDBC options that contains url, table and other information.
    * @param outputSchema - The schema of the columns or aggregate columns to SELECT.
    * @param groupByColumns - The pushed down group by columns.
+   * @param sample - The pushed down tableSample.
    * @param limit - The pushed down limit. If the value is 0, it means no limit or limit
    *                is not pushed down.
-   * @param sample - The pushed down tableSample.
+   * @param sortValues - The sort values cooperates with limit to realize top N.
    *
    * @return An RDD representing "SELECT requiredColumns FROM fqTable".
    */
+  // scalastyle:off argcount
   def scanTable(
       sc: SparkContext,
       schema: StructType,
@@ -167,7 +170,8 @@ object JDBCRDD extends Logging {
       outputSchema: Option[StructType] = None,
       groupByColumns: Option[Array[String]] = None,
       sample: Option[TableSampleInfo] = None,
-      limit: Int = 0): RDD[InternalRow] = {
+      limit: Int = 0,
+      sortOrders: Array[SortOrder] = Array.empty[SortOrder]): RDD[InternalRow] = {
     val url = options.url
     val dialect = JdbcDialects.get(url)
     val quotedColumns = if (groupByColumns.isEmpty) {
@@ -187,8 +191,10 @@ object JDBCRDD extends Logging {
       options,
       groupByColumns,
       sample,
-      limit)
+      limit,
+      sortOrders)
   }
+  // scalastyle:on argcount
 }
 
 /**
@@ -207,7 +213,8 @@ private[jdbc] class JDBCRDD(
     options: JDBCOptions,
     groupByColumns: Option[Array[String]],
     sample: Option[TableSampleInfo],
-    limit: Int)
+    limit: Int,
+    sortOrders: Array[SortOrder])
   extends RDD[InternalRow](sc, Nil) {
 
   /**
@@ -255,6 +262,14 @@ private[jdbc] class JDBCRDD(
     }
   }
 
+  private def getOrderByClause: String = {
+    if (sortOrders.nonEmpty) {
+      s" ORDER BY ${sortOrders.map(_.describe()).mkString(", ")}"
+    } else {
+      ""
+    }
+  }
+
   /**
    * Runs the SQL query against the JDBC driver.
    *
@@ -339,7 +354,7 @@ private[jdbc] class JDBCRDD(
     val myLimitClause: String = dialect.getLimitClause(limit)
 
     val sqlText = s"SELECT $columnList FROM ${options.tableOrQuery} $myTableSampleClause" +
-      s" $myWhereClause $getGroupByClause $myLimitClause"
+      s" $myWhereClause $getGroupByClause $getOrderByClause $myLimitClause"
     stmt = conn.prepareStatement(sqlText,
         ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY)
     stmt.setFetchSize(options.fetchSize)

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRelation.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JDBCRelation.scala
@@ -27,6 +27,7 @@ import org.apache.spark.sql.{DataFrame, Row, SaveMode, SparkSession, SQLContext}
 import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.util.{DateFormatter, DateTimeUtils, TimestampFormatter}
 import org.apache.spark.sql.catalyst.util.DateTimeUtils.{getZoneId, stringToDate, stringToTimestamp}
+import org.apache.spark.sql.connector.expressions.SortOrder
 import org.apache.spark.sql.errors.QueryCompilationErrors
 import org.apache.spark.sql.execution.datasources.v2.TableSampleInfo
 import org.apache.spark.sql.internal.SQLConf
@@ -301,7 +302,8 @@ private[sql] case class JDBCRelation(
       filters: Array[Filter],
       groupByColumns: Option[Array[String]],
       tableSample: Option[TableSampleInfo],
-      limit: Int): RDD[Row] = {
+      limit: Int,
+      sortOrders: Array[SortOrder]): RDD[Row] = {
     // Rely on a type erasure hack to pass RDD[InternalRow] back as RDD[Row]
     JDBCRDD.scanTable(
       sparkSession.sparkContext,
@@ -313,7 +315,8 @@ private[sql] case class JDBCRelation(
       Some(finalSchema),
       groupByColumns,
       tableSample,
-      limit).asInstanceOf[RDD[Row]]
+      limit,
+      sortOrders).asInstanceOf[RDD[Row]]
   }
 
   override def insert(data: DataFrame, overwrite: Boolean): Unit = {

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/PushDownUtils.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/PushDownUtils.scala
@@ -22,10 +22,10 @@ import scala.collection.mutable
 import org.apache.spark.sql.catalyst.expressions.{AttributeReference, AttributeSet, Expression, NamedExpression, PredicateHelper, SchemaPruning}
 import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression
 import org.apache.spark.sql.catalyst.util.CharVarcharUtils
-import org.apache.spark.sql.connector.expressions.FieldReference
+import org.apache.spark.sql.connector.expressions.{FieldReference, SortOrder}
 import org.apache.spark.sql.connector.expressions.aggregate.Aggregation
 import org.apache.spark.sql.connector.expressions.filter.{Filter => V2Filter}
-import org.apache.spark.sql.connector.read.{Scan, ScanBuilder, SupportsPushDownAggregates, SupportsPushDownFilters, SupportsPushDownLimit, SupportsPushDownRequiredColumns, SupportsPushDownTableSample, SupportsPushDownV2Filters}
+import org.apache.spark.sql.connector.read.{Scan, ScanBuilder, SupportsPushDownAggregates, SupportsPushDownFilters, SupportsPushDownLimit, SupportsPushDownRequiredColumns, SupportsPushDownTableSample, SupportsPushDownTopN, SupportsPushDownV2Filters}
 import org.apache.spark.sql.execution.datasources.{DataSourceStrategy, PushableColumnWithoutNestedColumn}
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.sources
@@ -158,6 +158,17 @@ object PushDownUtils extends PredicateHelper {
     }
   }
 
+  /**
+   * Pushes down top N to the data source Scan
+   */
+  def pushTopN(scanBuilder: ScanBuilder, order: Array[SortOrder], limit: Int): Boolean = {
+    scanBuilder match {
+      case s: SupportsPushDownTopN =>
+        s.pushTopN(order, limit)
+      case _ => false
+    }
+  }
+
   /**
    * Applies column pruning to the data source, w.r.t. the references of the given expressions.
    *

diff --git a/...re/src/main/scala/org/apache/spark/sql/execution/datasources/v2/PushedDownOperators.scala b/...re/src/main/scala/org/apache/spark/sql/execution/datasources/v2/PushedDownOperators.scala
@@ -17,6 +17,7 @@
 
 package org.apache.spark.sql.execution.datasources.v2
 
+import org.apache.spark.sql.connector.expressions.SortOrder
 import org.apache.spark.sql.connector.expressions.aggregate.Aggregation
 
 /**
@@ -25,4 +26,7 @@ import org.apache.spark.sql.connector.expressions.aggregate.Aggregation
 case class PushedDownOperators(
     aggregation: Option[Aggregation],
     sample: Option[TableSampleInfo],
-    limit: Option[Int])
+    limit: Option[Int],
+    sortValues: Seq[SortOrder]) {
+  assert((limit.isEmpty && sortValues.isEmpty) || limit.isDefined)
+}
diff --git a/...src/main/scala/org/apache/spark/sql/execution/datasources/v2/V2ScanRelationPushDown.scala b/...src/main/scala/org/apache/spark/sql/execution/datasources/v2/V2ScanRelationPushDown.scala
@@ -23,8 +23,9 @@ import org.apache.spark.sql.catalyst.expressions.{And, Attribute, AttributeRefer
 import org.apache.spark.sql.catalyst.expressions.aggregate
 import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression
 import org.apache.spark.sql.catalyst.planning.ScanOperation
-import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Filter, LeafNode, Limit, LogicalPlan, Project, Sample}
+import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, Filter, LeafNode, Limit, LocalLimit, LogicalPlan, Project, Sample, Sort}
 import org.apache.spark.sql.catalyst.rules.Rule
+import org.apache.spark.sql.connector.expressions.SortOrder
 import org.apache.spark.sql.connector.expressions.aggregate.Aggregation
 import org.apache.spark.sql.connector.read.{Scan, ScanBuilder, SupportsPushDownAggregates, SupportsPushDownFilters, V1Scan}
 import org.apache.spark.sql.execution.datasources.DataSourceStrategy
@@ -246,17 +247,39 @@ object V2ScanRelationPushDown extends Rule[LogicalPlan] with PredicateHelper {
     }
   }
 
+  private def pushDownLimit(plan: LogicalPlan, limit: Int): LogicalPlan = plan match {
+    case operation @ ScanOperation(_, filter, sHolder: ScanBuilderHolder) if filter.isEmpty =>
+      val limitPushed = PushDownUtils.pushLimit(sHolder.builder, limit)
+      if (limitPushed) {
+        sHolder.pushedLimit = Some(limit)
+      }
+      operation
+    case s @ Sort(order, _, operation @ ScanOperation(_, filter, sHolder: ScanBuilderHolder))
+      if filter.isEmpty =>
+      val orders = DataSourceStrategy.translateSortOrders(order)
+      if (orders.length == order.length) {
+        val topNPushed = PushDownUtils.pushTopN(sHolder.builder, orders.toArray, limit)
+        if (topNPushed) {
+          sHolder.pushedLimit = Some(limit)
+          sHolder.sortOrders = orders
+          operation
+        } else {
+          s
+        }
+      } else {
+        s
+      }
+    case p: Project =>
+      val newChild = pushDownLimit(p.child, limit)
+      p.withNewChildren(Seq(newChild))
+    case other => other
+  }
+
   def applyLimit(plan: LogicalPlan): LogicalPlan = plan.transform {
     case globalLimit @ Limit(IntegerLiteral(limitValue), child) =>
-      child match {
-        case ScanOperation(_, filter, sHolder: ScanBuilderHolder) if filter.length == 0 =>
-          val limitPushed = PushDownUtils.pushLimit(sHolder.builder, limitValue)
-          if (limitPushed) {
-            sHolder.pushedLimit = Some(limitValue)
-          }
-          globalLimit
-        case _ => globalLimit
-      }
+      val newChild = pushDownLimit(child, limitValue)
+      val newLocalLimit = globalLimit.child.asInstanceOf[LocalLimit].withNewChildren(Seq(newChild))
+      globalLimit.withNewChildren(Seq(newLocalLimit))
   }
 
   private def getWrappedScan(
@@ -270,8 +293,8 @@ object V2ScanRelationPushDown extends Rule[LogicalPlan] with PredicateHelper {
             f.pushedFilters()
           case _ => Array.empty[sources.Filter]
         }
-        val pushedDownOperators =
-          PushedDownOperators(aggregation, sHolder.pushedSample, sHolder.pushedLimit)
+        val pushedDownOperators = PushedDownOperators(aggregation,
+          sHolder.pushedSample, sHolder.pushedLimit, sHolder.sortOrders)
         V1ScanWrapper(v1, pushedFilters, pushedDownOperators)
       case _ => scan
     }
@@ -284,6 +307,8 @@ case class ScanBuilderHolder(
     builder: ScanBuilder) extends LeafNode {
   var pushedLimit: Option[Int] = None
 
+  var sortOrders: Seq[SortOrder] = Seq.empty[SortOrder]
+
   var pushedSample: Option[TableSampleInfo] = None
 }
 

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCScan.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/jdbc/JDBCScan.scala
@@ -18,6 +18,7 @@ package org.apache.spark.sql.execution.datasources.v2.jdbc
 
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{Row, SQLContext}
+import org.apache.spark.sql.connector.expressions.SortOrder
 import org.apache.spark.sql.connector.read.V1Scan
 import org.apache.spark.sql.execution.datasources.jdbc.JDBCRelation
 import org.apache.spark.sql.execution.datasources.v2.TableSampleInfo
@@ -31,7 +32,8 @@ case class JDBCScan(
     pushedAggregateColumn: Array[String] = Array(),
     groupByColumns: Option[Array[String]],
     tableSample: Option[TableSampleInfo],
-    pushedLimit: Int) extends V1Scan {
+    pushedLimit: Int,
+    sortOrders: Array[SortOrder]) extends V1Scan {
 
   override def readSchema(): StructType = prunedSchema
 
@@ -46,8 +48,8 @@ case class JDBCScan(
         } else {
           pushedAggregateColumn
         }
-        relation.buildScan(
-          columnList, prunedSchema, pushedFilters, groupByColumns, tableSample, pushedLimit)
+        relation.buildScan(columnList, prunedSchema, pushedFilters, groupByColumns, tableSample,
+          pushedLimit, sortOrders)
       }
     }.asInstanceOf[T]
   }