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src/sql/optimizer/ob_raw_expr_add_to_context.cpp

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+/**
+ * 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.
+ */
+
+#define USING_LOG_PREFIX SQL_OPT
+#include "ob_raw_expr_add_to_context.h"
+
+/// interface of ObRawExprVisitor
+using namespace oceanbase::sql;
+using namespace oceanbase::common;
+
+int ObRawExprAddToContext::add_to_context(ObRawExpr& expr)
+{
+  return expr.postorder_accept(*this);
+}
+
+int ObRawExprAddToContext::visit(ObConstRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+  UNUSED(expr);
+  return ret;
+}
+
+int ObRawExprAddToContext::visit(ObVarRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+  UNUSED(expr);
+  return ret;
+}
+
+int ObRawExprAddToContext::visit(ObQueryRefRawExpr& expr)
+{
+  return add_expr(expr);
+}
+
+int ObRawExprAddToContext::visit(ObColumnRefRawExpr& expr)
+{
+  return add_expr(expr);
+}
+
+int ObRawExprAddToContext::visit(ObOpRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+  if (expr.has_generalized_column() && T_OP_ROW != expr.get_expr_type()) {
+    ret = add_expr(expr);
+  }
+  return ret;
+}
+
+int ObRawExprAddToContext::visit(ObCaseOpRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+  if (expr.has_generalized_column()) {
+    ret = add_expr(expr);
+  }
+  return ret;
+}
+
+int ObRawExprAddToContext::visit(ObAggFunRawExpr& expr)
+{
+  //  /* When we recursively add the expressions to the list, it is because the expression
+  //     can only be produced by us - ie. the aggregation function of group by. In this case
+  //     we would want to skip adding the aggregation funtion to the request list */
+  //  int ret = OB_SUCCESS;
+  ////  UNUSED(expr);
+  ////  return ret;
+  //  if (expr.has_flag(CNT_COLUMN) || IS_COUNT_STAR(&expr)) {
+  //    return add_expr(expr);
+  //  }
+  //
+  //  return ret;
+  return add_expr(expr);
+}
+
+int ObRawExprAddToContext::visit(ObSysFunRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+  if (expr.has_generalized_column() || expr.has_flag(CNT_RAND_FUNC)) {
+    ret = add_expr(expr);
+  }
+  return ret;
+}
+
+int ObRawExprAddToContext::visit(ObSetOpRawExpr& expr)
+{
+  return add_expr(expr);
+}
+
+int ObRawExprAddToContext::visit(ObWinFunRawExpr& expr)
+{
+  return add_expr(expr);
+}
+
+int ObRawExprAddToContext::visit(ObPseudoColumnRawExpr& expr)
+{
+  return add_expr(expr);
+}
+
+/**
+ *  TODO: the complexity of the algorithm used in add_expr is quite high. *  We may need to revisit it later if it turns
+ * out to be an optimization we have to do.
+ */
+int ObRawExprAddToContext::add_expr(ObRawExpr& expr)
+{
+  int ret = OB_SUCCESS;
+
+  if (OB_ISNULL(ctx_)) {
+    ret = OB_ERR_UNEXPECTED;
+    LOG_WARN("invalid argument", K(ret));
+  } else {
+    ExprProducer* existing_producer = NULL;
+    if (!ObOptimizerUtil::find_expr(ctx_, expr, existing_producer)) {
+      ExprProducer expr_producer(&expr, consumer_id_);
+      if (OB_FAIL(ctx_->push_back(expr_producer))) {
+        LOG_PRINT_EXPR(WARN, "failed to add expr to request list", &expr, "# of expr", ctx_->count());
+      } else {
+        LOG_PRINT_EXPR(DEBUG, "add expr to request list", &expr, "# of expr", ctx_->count());
+      }
+    } else if (OB_ISNULL(existing_producer)) {
+      ret = OB_ERR_UNEXPECTED;
+      LOG_WARN("existing_producer is unexpected null", K(ret));
+    } else {
+      // if we need the same expr below the predetermined producer
+      // restore predetermined_producer_ so it can be produced here
+      LOG_TRACE("restore predetermined_producer",
+          K(existing_producer->expr_),
+          K(existing_producer->producer_id_),
+          K(existing_producer->consumer_id_));
+      existing_producer->producer_id_ = OB_INVALID_ID;
+    }
+  }
+
+  return ret;
+}