[CALCITE-6837] Invalid code generated for ROW_NUMBER function in Enum…

…erable convention
asolimando · Feb 26, 2025 · 4ee2e41 · 4ee2e41
1 parent 3242604
commit 4ee2e41
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Showing 3 changed files with 67 additions and 13 deletions.
diff --git a/core/src/main/java/org/apache/calcite/adapter/jdbc/JdbcToEnumerableConverter.java b/core/src/main/java/org/apache/calcite/adapter/jdbc/JdbcToEnumerableConverter.java
@@ -26,6 +26,7 @@
 import org.apache.calcite.adapter.java.JavaTypeFactory;
 import org.apache.calcite.config.CalciteSystemProperty;
 import org.apache.calcite.linq4j.tree.BlockBuilder;
+import org.apache.calcite.linq4j.tree.BlockStatement;
 import org.apache.calcite.linq4j.tree.ConstantExpression;
 import org.apache.calcite.linq4j.tree.Expression;
 import org.apache.calcite.linq4j.tree.Expressions;
@@ -133,7 +134,13 @@ protected JdbcToEnumerableConverter(
     default:
       calendar_ = null;
     }
-    if (fieldCount == 1) {
+    if (fieldCount == 0) {
+      // return (Object) null;
+      final ParameterExpression value_ =
+          Expressions.parameter(Object.class, builder.newName("value"));
+      builder.add(Expressions.declare(Modifier.FINAL, value_, null));
+      builder.add(Expressions.return_(null, value_));
+    } else if (fieldCount == 1) {
       final ParameterExpression value_ =
           Expressions.parameter(Object.class, builder.newName("value"));
       builder.add(Expressions.declare(Modifier.FINAL, value_, null));
@@ -155,22 +162,53 @@ protected JdbcToEnumerableConverter(
     }
     final ParameterExpression e_ =
         Expressions.parameter(SQLException.class, builder.newName("e"));
+    BlockStatement valueBlock;
+    if (fieldCount == 0) {
+      // For some queries, we don't need to rely on a specific column value in the data source,
+      // we only need to know the number of rows in the table.
+      // For example: "select row_number() over () from dept"
+      // we can't push down the "row_number() over ()"
+      // So the generated code should be:
+      // public org.apache.calcite.linq4j.function.Function0 apply(
+      //    final java.sql.ResultSet resultSet) {
+      //  return new org.apache.calcite.linq4j.function.Function0() {
+      //    public Object apply() {
+      //      return (Object) null;
+      //    }
+      //  };
+      //  }
+      valueBlock = builder.toBlock();
+    } else {
+      // public org.apache.calcite.linq4j.function.Function0 apply(
+      //    final java.sql.ResultSet resultSet) {
+      //  return new org.apache.calcite.linq4j.function.Function0() {
+      //    public Object apply() {
+      //      try {
+      //        return resultSet.getString(1);
+      //      } catch (java.sql.SQLException e) {
+      //        throw new RuntimeException(
+      //            e);
+      //      }
+      //    }
+      //  };
+      //  }
+      valueBlock =
+          Expressions.block(
+              Expressions.tryCatch(
+              builder.toBlock(),
+              Expressions.catch_(
+                  e_,
+                  Expressions.throw_(
+                      Expressions.new_(
+                          RuntimeException.class,
+                          e_)))));
+    }
     final Expression rowBuilderFactory_ =
         builder0.append("rowBuilderFactory",
             Expressions.lambda(
                 Expressions.block(
                     Expressions.return_(null,
-                        Expressions.lambda(
-                            Expressions.block(
-                                Expressions.tryCatch(
-                                    builder.toBlock(),
-                                    Expressions.catch_(
-                                        e_,
-                                        Expressions.throw_(
-                                            Expressions.new_(
-                                                RuntimeException.class,
-                                                e_)))))))),
-                resultSet_));
+                        Expressions.lambda(valueBlock))), resultSet_));
 
     final Expression enumerable;
 

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
@@ -525,7 +525,10 @@ public Result visit(Project e) {
         }
         addSelect(selectList, sqlExpr, e.getRowType());
       }
-
+      // We generate "SELECT 1 FROM EMP" replace "SELECT FROM EMP"
+      if (selectList.isEmpty()) {
+        selectList.add(SqlLiteral.createExactNumeric("1", POS));
+      }
       final SqlNodeList selectNodeList = new SqlNodeList(selectList, POS);
       if (builder.select.getGroup() == null
           && builder.select.getHaving() == null

diff --git a/core/src/test/java/org/apache/calcite/test/JdbcTest.java b/core/src/test/java/org/apache/calcite/test/JdbcTest.java
@@ -4782,6 +4782,19 @@ private void startOfGroupStep3(String startOfGroup) {
             "deptno=20; empid=200; commission=500; R=1; RCNF=1; RCNL=1; R=1; RD=1");
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-6837">[CALCITE-6837]
+   * Invalid code generated for ROW_NUMBER function in Enumerable convention</a>. */
+  @Test void testWinRowNumber1() {
+    CalciteAssert.that()
+        .with(CalciteAssert.Config.JDBC_SCOTT)
+        .query("select row_number() over () from dept")
+        .returnsUnordered("EXPR$0=1",
+            "EXPR$0=2",
+            "EXPR$0=3",
+            "EXPR$0=4");
+  }
+
   /** Tests UNBOUNDED PRECEDING clause. */
   @Test void testOverUnboundedPreceding() {
     CalciteAssert.hr()