TAJO-975: alias name which is the same to existing column name may cause...

tajo-core/src/main/java/org/apache/tajo/engine/planner/rewrite/ProjectionPushDownRule.java

@@ -191,6 +191,7 @@ private String add(String specifiedName, EvalNode evalNode) throws PlanningExcep
       // if a name already exists, it only just keeps an actual
       // expression instead of a column reference.
       if (nameToIdBiMap.containsKey(specifiedName)) {
+
         int refId = nameToIdBiMap.get(specifiedName);
         EvalNode found = idToEvalBiMap.get(refId);
         if (found != null) {
@@ -204,7 +205,16 @@ private String add(String specifiedName, EvalNode evalNode) throws PlanningExcep
             }
 
             if (found.getType() == EvalType.FIELD) {
+              Integer daggling = idToEvalBiMap.inverse().get(evalNode);
               idToEvalBiMap.forcePut(refId, evalNode);
+              if (daggling != null) {
+                String name = getPrimaryName(daggling);
+                idToNamesMap.remove(daggling);
+                nameToIdBiMap.put(name, refId);
+                if (!idToNamesMap.get(refId).contains(name)) {
+                  TUtil.putToNestedList(idToNamesMap, refId, name);
+                }
+              }
             }
           }
         }

tajo-core/src/test/java/org/apache/tajo/engine/query/TestSelectQuery.java

@@ -138,6 +138,15 @@ public final void testSelectColumnAliasExistingInRelation2() throws Exception {
     cleanupQuery(res);
   }
 
+  @Test
+  public final void testSelectColumnAliasExistingInRelation3() throws Exception {
+    // This is a reproduction code and validator of TAJO-975 Bug
+    // Please see TAJO-975 in order to know this test in detail.
+    ResultSet res = executeQuery();
+    assertResultSet(res);
+    cleanupQuery(res);
+  }
+
 
   @Test
   public final void testSelectSameConstantsWithDifferentAliases() throws Exception {

tajo-core/src/test/resources/queries/TestSelectQuery/testSelectColumnAliasExistingInRelation3.sql

@@ -0,0 +1,19 @@
+SELECT l_orderkey FROM (
+
+-- actual test query
+  SELECT
+    T1.l_orderkey
+  FROM
+    LINEITEM
+  INNER JOIN (
+    SELECT
+      T1.l_orderkey
+    FROM (
+      SELECT
+        LINEITEM.l_orderkey AS l_orderkey
+      FROM
+        LINEITEM
+    ) T1
+  ) T1 ON LINEITEM.l_orderkey=T1.l_orderkey
+
+) A ORDER BY l_orderkey; -- for determinant query result

tajo-core/src/test/resources/results/TestSelectQuery/testSelectColumnAliasExistingInRelation3.result

@@ -0,0 +1,11 @@
+l_orderkey
+-------------------------------
+1
+1
+1
+1
+2
+3
+3
+3
+3