Cache Table is not working while subquery has alias in its project list

Author: chenghao-intel

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala

@@ -135,16 +135,25 @@ abstract class LogicalPlan extends QueryPlan[LogicalPlan] with Logging {
   /** Args that have cleaned such that differences in expression id should not affect equality */
   protected lazy val cleanArgs: Seq[Any] = {
     val input = children.flatMap(_.output)
+    def cleanExpression(e: Expression) = e match {
+      case a: Alias =>
+        // As the root of the expression, Alias will always take an arbitrary exprId, we need
+        // to erase that for equality testing.
+        val cleanedExprId = Alias(a.child, a.name)(ExprId(-1), a.qualifiers)
+        BindReferences.bindReference(cleanedExprId, input, allowFailures = true)
+      case other => BindReferences.bindReference(other, input, allowFailures = true)
+    }
+
     productIterator.map {
       // Children are checked using sameResult above.
       case tn: TreeNode[_] if containsChild(tn) => null
-      case e: Expression => BindReferences.bindReference(e, input, allowFailures = true)
+      case e: Expression => cleanExpression(e)
       case s: Option[_] => s.map {
-        case e: Expression => BindReferences.bindReference(e, input, allowFailures = true)
+        case e: Expression => cleanExpression(e)
         case other => other
       }
       case s: Seq[_] => s.map {
-        case e: Expression => BindReferences.bindReference(e, input, allowFailures = true)
+        case e: Expression => cleanExpression(e)
         case other => other
       }
       case other => other

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

@@ -203,4 +203,18 @@ class CachedTableSuite extends QueryTest {
     sql("DROP TABLE refreshTable")
     Utils.deleteRecursively(tempPath)
   }
+
+  test("SPARK-10327 Cache Table is not working while subquery has alias in its project list") {
+    import org.apache.spark.sql.hive.execution.HiveTableScan
+    sql("select key, value, key + 1 from src").registerTempTable("abc")
+    cacheTable("abc")
+
+    val sparkPlan = sql(
+      """select a.key, b.key, c.key from
+        |abc a join abc b on a.key=b.key
+        |join abc c on a.key=c.key""".stripMargin).queryExecution.sparkPlan
+
+    assert(sparkPlan.collect { case e: InMemoryColumnarTableScan => e }.size === 3)
+    assert(sparkPlan.collect { case e: HiveTableScan => e }.size === 0)
+  }
 }