[SPARK-29800][SQL] Rewrite non-correlated EXISTS subquery use ScalaSubquery to optimize perf

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/subquery.scala

@@ -62,11 +62,13 @@ abstract class SubqueryExpression(
 
 object SubqueryExpression {
   /**
-   * Returns true when an expression contains an IN or EXISTS subquery and false otherwise.
+   * Returns true when an expression contains an IN or correlated EXISTS subquery
+   * and false otherwise.
    */
-  def hasInOrExistsSubquery(e: Expression): Boolean = {
+  def hasInOrCorrelatedExistsSubquery(e: Expression): Boolean = {
     e.find {
-      case _: ListQuery | _: Exists => true
+      case _: ListQuery => true
+      case _: Exists if e.children.nonEmpty => true
       case _ => false
     }.isDefined
   }
@@ -302,7 +304,10 @@ case class ListQuery(
 }
 
 /**
- * The [[Exists]] expression checks if a row exists in a subquery given some correlated condition.
+ * The [[Exists]] expression checks if a row exists in a subquery given some correlated condition
+ * or some uncorrelated condition.
+ *
+ * 1. correlated condition:
  *
  * For example (SQL):
  * {{{
@@ -312,6 +317,17 @@ case class ListQuery(
  *                   FROM    b
  *                   WHERE   b.id = a.id)
  * }}}
+ *
+ * 2. uncorrelated condition example:
+ *
+ * For example (SQL):
+ * {{{
+ *   SELECT  *
+ *   FROM    a
+ *   WHERE   EXISTS (SELECT  *
+ *                   FROM    b
+ *                   WHERE   b.id > 10)
+ * }}}
  */
 case class Exists(
     plan: LogicalPlan,

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala

@@ -128,6 +128,7 @@ abstract class Optimizer(catalogManager: CatalogManager)
       EliminateSubqueryAliases,
       EliminateView,
       ReplaceExpressions,
+      RewriteNonCorrelatedExists,
       ComputeCurrentTime,
       GetCurrentDatabase(catalogManager),
       RewriteDistinctAggregates,

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/finishAnalysis.scala

@@ -52,6 +52,21 @@ object ReplaceExpressions extends Rule[LogicalPlan] {
   }
 }
 
+/**
+ * Rewrite non correlated exists subquery to use ScalarSubquery
+ *   WHERE EXISTS (SELECT A FROM TABLE B WHERE COL1 > 10)
+ * will be rewritten to
+ *   WHERE (SELECT 1 FROM (SELECT A FROM TABLE B WHERE COL1 > 10) LIMIT 1) IS NOT NULL
+ */
+object RewriteNonCorrelatedExists extends Rule[LogicalPlan] {
+  override def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
+    case exists: Exists if exists.children.isEmpty =>
+      IsNotNull(
+        ScalarSubquery(
+          plan = Limit(Literal(1), Project(Seq(Alias(Literal(1), "col")()), exists.plan)),
+          exprId = exists.exprId))
+  }
+}
 
 /**
  * Computes the current date and time to make sure we return the same result in a single query.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala

@@ -96,7 +96,8 @@ object RewritePredicateSubquery extends Rule[LogicalPlan] with PredicateHelper {
   def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case Filter(condition, child) =>
       val (withSubquery, withoutSubquery) =
-        splitConjunctivePredicates(condition).partition(SubqueryExpression.hasInOrExistsSubquery)
+        splitConjunctivePredicates(condition)
+          .partition(SubqueryExpression.hasInOrCorrelatedExistsSubquery)
 
       // Construct the pruned filter condition.
       val newFilter: LogicalPlan = withoutSubquery match {

sql/core/src/test/scala/org/apache/spark/sql/CachedTableSuite.scala

@@ -28,7 +28,7 @@ import org.apache.spark.sql.catalyst.TableIdentifier
 import org.apache.spark.sql.catalyst.expressions.SubqueryExpression
 import org.apache.spark.sql.catalyst.plans.logical.{BROADCAST, Join, JoinStrategyHint, SHUFFLE_HASH}
 import org.apache.spark.sql.catalyst.util.DateTimeConstants
-import org.apache.spark.sql.execution.{RDDScanExec, SparkPlan}
+import org.apache.spark.sql.execution.{ExecSubqueryExpression, RDDScanExec, SparkPlan}
 import org.apache.spark.sql.execution.columnar._
 import org.apache.spark.sql.execution.exchange.ShuffleExchangeExec
 import org.apache.spark.sql.functions._
@@ -89,10 +89,19 @@ class CachedTableSuite extends QueryTest with SQLTestUtils with SharedSparkSessi
     sum
   }
 
+  private def getNumInMemoryTablesInSubquery(plan: SparkPlan): Int = {
+    plan.expressions.flatMap(_.collect {
+      case sub: ExecSubqueryExpression => getNumInMemoryTablesRecursively(sub.plan)
+    }).sum
+  }
+
   private def getNumInMemoryTablesRecursively(plan: SparkPlan): Int = {
     plan.collect {
-      case InMemoryTableScanExec(_, _, relation) =>
-        getNumInMemoryTablesRecursively(relation.cachedPlan) + 1
+      case inMemoryTable @ InMemoryTableScanExec(_, _, relation) =>
+        getNumInMemoryTablesRecursively(relation.cachedPlan) +
+          getNumInMemoryTablesInSubquery(inMemoryTable) + 1
+      case p =>
+        getNumInMemoryTablesInSubquery(p)
     }.sum
   }
 

sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala

@@ -891,9 +891,9 @@ class SubquerySuite extends QueryTest with SharedSparkSession {
 
         val sqlText =
           """
-            |SELECT * FROM t1
+            |SELECT * FROM t1 a
             |WHERE
-            |NOT EXISTS (SELECT * FROM t1)
+            |NOT EXISTS (SELECT * FROM t1 b WHERE a.i = b.i)
           """.stripMargin
         val optimizedPlan = sql(sqlText).queryExecution.optimizedPlan
         val join = optimizedPlan.collectFirst { case j: Join => j }.get