[CALCITE-6221] JDBC adapter generates invalid query when the same tab…

…le is joined multiple times
sap-contributions · Jan 30, 2024 · 951b324 · 951b324
1 parent 75511b8
commit 951b324
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Showing 3 changed files with 262 additions and 147 deletions.
diff --git a/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java b/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
@@ -225,7 +225,7 @@ public Result visit(Join e) {
       break;
     }
     final Result leftResult = visitInput(e, 0).resetAlias();
-    final Result rightResult = visitInput(e, 1).resetAlias();
+    Result rightResult = maybeFixRenamedFields(visitInput(e, 1).resetAlias(), e);
     final Context leftContext = leftResult.qualifiedContext();
     final Context rightContext = rightResult.qualifiedContext();
     final SqlNode sqlCondition;
@@ -257,6 +257,53 @@ public Result visit(Join e) {
     return result(join, leftResult, rightResult);
   }
 
+  private Result maybeFixRenamedFields(Result rightResult, Join e) {
+    Frame last = stack.peekLast();
+    if (last != null && last.r instanceof TableModify) {
+      return rightResult;
+    }
+    if (stack.stream().noneMatch(it -> it.r instanceof Filter)) {
+      return rightResult;
+    }
+    List<String> rightFieldNames = e.getRight().getRowType().getFieldNames();
+    List<String> fieldNames = e.getRowType().getFieldNames();
+    int offset = e.getLeft().getRowType().getFieldCount();
+    boolean hasFieldNameCollision = false;
+    for (int i = 0; i < rightFieldNames.size(); i++) {
+      if (!rightFieldNames.get(i).equals(fieldNames.get(offset + i))) {
+        hasFieldNameCollision = true;
+      }
+    }
+    if (!hasFieldNameCollision) {
+      return rightResult;
+    }
+    Builder builder = rightResult.builder(e);
+    List<SqlNode> oldSelectList = new ArrayList<>();
+    if (builder.select.getSelectList() == SqlNodeList.SINGLETON_STAR) {
+      for (int i = 0; i < rightFieldNames.size(); i++) {
+        oldSelectList.add(new SqlIdentifier(rightFieldNames.get(i), POS));
+      }
+    } else {
+      for (SqlNode node : builder.select.getSelectList().getList()) {
+        oldSelectList.add(requireNonNull(node, "node"));
+      }
+    }
+    List<SqlNode> selectList = new ArrayList<>();
+    // The entries in fieldNames are unique, since they have been generated
+    // using SqlValidatorUtil.deriveJoinRowType
+    for (int i = 0; i < rightFieldNames.size(); i++) {
+      SqlNode column = oldSelectList.get(i);
+      if (!rightFieldNames.get(i).equals(fieldNames.get(offset + i))) {
+        column =
+            SqlStdOperatorTable.AS.createCall(POS, SqlUtil.stripAs(column),
+                new SqlIdentifier(fieldNames.get(offset + i), POS));
+      }
+      selectList.add(column);
+    }
+    builder.setSelect(new SqlNodeList(selectList, POS));
+    return builder.result();
+  }
+
   protected Result visitAntiOrSemiJoin(Join e) {
     final Result leftResult = visitInput(e, 0).resetAlias();
     final Result rightResult = visitInput(e, 1).resetAlias();