Duplicate column check when distinct

apache · Feb 7, 2024 · d5bbd52 · d5bbd52
1 parent 0cb5627
commit d5bbd52
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Showing 2 changed files with 25 additions and 5 deletions.
diff --git a/cayenne/src/main/java/org/apache/cayenne/access/translator/select/OrderingStage.java b/cayenne/src/main/java/org/apache/cayenne/access/translator/select/OrderingStage.java
@@ -56,11 +56,18 @@ private void processOrdering(QualifierTranslator qualifierTranslator, Translator
 
         // If query is DISTINCT then we need to add all ORDER BY clauses as result columns
         if(!context.isDistinctSuppression()) {
-            // TODO: need to check duplicates?
-            // need UPPER() function here too, as some DB expect exactly the same expression in select and in ordering
-            ResultNodeDescriptor descriptor = context.addResultNode(nodeBuilder.build().deepCopy());
-            if(exp instanceof ASTAggregateFunctionCall) {
-                descriptor.setAggregate(true);
+            // Duplicate column check
+            String nodeStr = translatedNode.toString();
+            boolean isNotPresent = context.getResultNodeList().stream()
+                        .map( result -> result.getNode().toString() )
+                        .noneMatch( node -> node.equals( nodeStr ) );
+
+            if ( isNotPresent ) {
+                // deepCopy as some DB expect exactly the same expression in select and in ordering
+                ResultNodeDescriptor descriptor = context.addResultNode(nodeBuilder.build().deepCopy());
+                if(exp instanceof ASTAggregateFunctionCall) {
+                    descriptor.setAggregate(true);
+                }
             }
         }
 

diff --git a/cayenne/src/test/java/org/apache/cayenne/access/translator/select/OrderingStageTest.java b/cayenne/src/test/java/org/apache/cayenne/access/translator/select/OrderingStageTest.java
@@ -76,6 +76,7 @@ public void prepareContext() {
                         .withDbEntity(dbEntity)
                         .withObjEntity(objEntity)
                         .build())
+                .withDistinct( true )
                 .build();
         context = new MockTranslatorContext(wrapper);
     }
@@ -108,4 +109,16 @@ public void perform() {
         assertEquals("path", columnNode.getColumn());
         assertEquals("Node { DESC}", child.getChild(0).getChild(1).toString());
     }
+
+    @Test
+    public void testNoDuplicateColumnsWhenDistinct() {
+        ColumnExtractorStage columnStage = new ColumnExtractorStage();
+        columnStage.perform(context);
+
+        OrderingStage orderingStage = new OrderingStage();
+        orderingStage.perform(context);
+
+        assertTrue(context.getQuery().isDistinct());
+        assertEquals(1, context.getResultNodeList().size());
+    }
 }