patch 4.0

src/sql/engine/expr/ob_expr_wrapper_inner.h

@@ -0,0 +1,59 @@
+/**
+ * Copyright (c) 2021 OceanBase
+ * OceanBase CE is licensed under Mulan PubL v2.
+ * You can use this software according to the terms and conditions of the Mulan PubL v2.
+ * You may obtain a copy of Mulan PubL v2 at:
+ *          http://license.coscl.org.cn/MulanPubL-2.0
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PubL v2 for more details.
+ */
+
+#ifndef OCEANBASE_EXPR_OB_EXPR_WRAPPER_INNER_H_
+#define OCEANBASE_EXPR_OB_EXPR_WRAPPER_INNER_H_
+
+#include "sql/engine/expr/ob_expr_operator.h"
+namespace oceanbase
+{
+namespace sql
+{
+
+//
+// remove_const() is added above const expr to resolve the const value overwrite problem
+// in static typing engine. e.g.:
+//
+//   update t1 set (c1, c2) = (select 1, 2 from t2);
+//
+// will be rewrite to:
+//   update t1 set (c1, c2) = (select remove_const(1), remove_const(2) from t2);
+//
+//
+// remove_const(1), remove_const(2) will be overwrite when subquery is empty
+// instead of const value: 1, 2
+//
+// see: https://yuque.antfin-inc.com/ob/sql/expression_result_overwrite#eaa08cb4
+//
+class ObExprWrapperInner : public ObFuncExprOperator
+{
+public:
+  explicit ObExprWrapperInner(common::ObIAllocator &alloc);
+  virtual ~ObExprWrapperInner() {}
+
+  virtual int calc_result_type1(ObExprResType &type,
+                                ObExprResType &arg,
+                                common::ObExprTypeCtx &type_ctx) const override;
+
+  virtual int cg_expr(ObExprCGCtx &op_cg_ctx,
+                      const ObRawExpr &raw_expr,
+                      ObExpr &rt_expr) const override;
+
+  static int eval_wrapper_inner(const ObExpr &expr, ObEvalCtx &ctx, ObDatum &expr_datum);
+
+private:
+  DISALLOW_COPY_AND_ASSIGN(ObExprWrapperInner);
+};
+
+} // namespace sql
+} // namespace oceanbase
+#endif // OCEANBASE_EXPR_OB_EXPR_WRAPPER_INNER_H_