221 lines
		
	
	
		
			8.2 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			221 lines
		
	
	
		
			8.2 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/**
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 * Copyright (c) 2021 OceanBase
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 * OceanBase CE is licensed under Mulan PubL v2.
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 * You can use this software according to the terms and conditions of the Mulan PubL v2.
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 * You may obtain a copy of Mulan PubL v2 at:
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 *          http://license.coscl.org.cn/MulanPubL-2.0
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 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
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 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
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 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
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 * See the Mulan PubL v2 for more details.
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 */
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#define USING_LOG_PREFIX SQL_OPT
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#include "ob_log_limit.h"
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#include "ob_log_group_by.h"
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#include "ob_log_operator_factory.h"
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#include "ob_log_sort.h"
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#include "ob_log_table_scan.h"
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#include "ob_optimizer_util.h"
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#include "ob_opt_est_cost.h"
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#include "ob_log_exchange.h"
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#include "sql/rewrite/ob_transform_utils.h"
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#include "sql/optimizer/ob_join_order.h"
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#include "common/ob_smart_call.h"
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using namespace oceanbase::sql;
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using namespace oceanbase::common;
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using namespace oceanbase::sql::log_op_def;
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int ObLogLimit::get_op_exprs(ObIArray<ObRawExpr*> &all_exprs)
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{
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  int ret = OB_SUCCESS;
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  //支持with ties功能,如果存在order by item,需要添加对应的order by item
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  ObSEArray<ObOrderDirection, 6> order_directions;
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  if (is_fetch_with_ties() && OB_FAIL(ObOptimizerUtil::split_expr_direction(
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                                                       order_items_,
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                                                       all_exprs,
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                                                       order_directions))) {
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    LOG_WARN("failed to split expr and direction", K(ret));
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  } else if (NULL != limit_expr_ && OB_FAIL(all_exprs.push_back(limit_expr_))) {
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    LOG_WARN("failed to push back expr", K(ret));
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  } else if (NULL != offset_expr_ && OB_FAIL(all_exprs.push_back(offset_expr_))) {
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    LOG_WARN("failed to push back expr", K(ret));
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  } else if (NULL != percent_expr_ && OB_FAIL(all_exprs.push_back(percent_expr_))) {
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    LOG_WARN("failed to push back expr", K(ret));
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  } else if (OB_FAIL(ObLogicalOperator::get_op_exprs(all_exprs))) {
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    LOG_WARN("failed to push back expr", K(ret));
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  } else {/*do nothing*/ }
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  return ret;
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}
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int ObLogLimit::est_cost()
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{
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  int ret = OB_SUCCESS;
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  double card = 0.0;
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  double op_cost = 0.0;
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  double cost = 0.0;
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  EstimateCostInfo param;
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  param.need_parallel_ = get_parallel();
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  if (OB_FAIL(do_re_est_cost(param, card_, op_cost_, cost_))) {
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    LOG_WARN("failed to est cost", K(ret));
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  } else {
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    LOG_TRACE("succeed to estimate limit-k cost", K(card_), K(op_cost_), K(cost_));
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  }
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  return ret;
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}
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int ObLogLimit::do_re_est_cost(EstimateCostInfo ¶m, double &card, double &op_cost, double &cost)
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{
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  int ret = OB_SUCCESS;
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  card = 0.0;
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  op_cost = 0.0;
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  cost = 0.0;
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  int64_t limit_count = -1;
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  int64_t offset_count = 0;
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  double limit_percent = -1;
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  ObLogicalOperator *child = NULL;
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  const int64_t parallel = param.need_parallel_;
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  if (OB_ISNULL(get_plan()) || OB_ISNULL(child = get_child(first_child))) {
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    ret = OB_ERR_UNEXPECTED;
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    LOG_WARN("get unexpected null", K(get_plan()), K(child), K(ret));
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  } else if (OB_UNLIKELY((parallel > 1 && (NULL != percent_expr_ || NULL != offset_expr_))
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                         || parallel < 1)) {
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    ret = OB_ERR_UNEXPECTED;
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    LOG_WARN("get unexpected parallel degree", K(ret), K(param), K(percent_expr_), K(offset_expr_));
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  } else if (!is_calc_found_rows_ &&
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             OB_FAIL(get_limit_offset_value(percent_expr_, limit_expr_, offset_expr_,
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                                            limit_percent, limit_count, offset_count))) {
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    LOG_WARN("failed to get limit offset value", K(ret));
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  } else {
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    card = 0 > param.need_row_count_ ? child->get_card() : param.need_row_count_;
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    if (0 <= limit_count) {
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      if (parallel > 1) {
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        card = std::min(card, child->get_card());
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        card = std::min(card, static_cast<double>(limit_count * parallel));
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      } else {
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        card = std::min(card, child->get_card() - offset_count);
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        card = std::min(card, static_cast<double>(limit_count));
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      }
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      card = std::max(0.0, card);
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      param.need_row_count_ = std::min(card + offset_count, child->get_card());
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    } else if (0 <= limit_percent) {
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      // reset need_row_count_ when exists limit_percent
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      card = std::min(card, child->get_card());
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      param.need_row_count_ = -1;
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    } else {
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      // 1. exists dynamic param in limit/offset or is_calc_found_rows_
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      // 2. has offset without limit / percent
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      card = std::min(card, child->get_card() - offset_count);
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      card = std::max(0.0, card);
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      param.need_row_count_ = std::min(card + offset_count, child->get_card());
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    }
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    if (OB_SUCC(ret)) {
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      double child_card = 0.0;
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      double child_cost = 0.0;
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      ObOptimizerContext &opt_ctx = get_plan()->get_optimizer_context();
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      if (OB_FAIL(child->re_est_cost(param, child_card, child_cost))) {
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        LOG_WARN("failed to re-est cost", K(ret));
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      } else {
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        op_cost = ObOptEstCost::cost_get_rows(child_card, opt_ctx);
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        cost = op_cost + child_cost;
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        child_card = 0 <= limit_percent
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                     ? std::max(child_card * limit_percent / 100 - offset_count, 0.0)
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                     : std::max(child_card - offset_count, 0.0);
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        child_card = std::max(0.0, child_card);
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        card = std::min(card, child_card);
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      }
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    }
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  }
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  return ret;
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}
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int ObLogLimit::check_output_dep_specific(ObRawExprCheckDep &checker)
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{
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  int ret = OB_SUCCESS;
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  if (NULL != limit_expr_) {
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    if (OB_FAIL(checker.check(*limit_expr_))) {
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      LOG_WARN("failed to check limit_count_", K(*limit_expr_), K(ret));
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    }
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  } else { /* Do nothing */ }
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  if (OB_SUCC(ret)) {
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    if (NULL != offset_expr_) {
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      if (OB_FAIL(checker.check(*offset_expr_))) {
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        LOG_WARN("failed to check limit_offset_", K(offset_expr_), K(ret));
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      }
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    } else { /* Do nothing */ }
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  }
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  if (OB_SUCC(ret)) {
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    if (NULL != percent_expr_) {
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      if (OB_FAIL(checker.check(*percent_expr_))) {
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        LOG_WARN("failed to check limit_percent_", K(percent_expr_), K(ret));
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      }
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    }
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  }
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  if (OB_SUCC(ret) && is_fetch_with_ties()) {
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    for (int64_t i = 0; OB_SUCC(ret) && i < order_items_.count(); ++i) {
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      ObRawExpr *cur_expr = order_items_.at(i).expr_;
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      if (OB_ISNULL(cur_expr)) {
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        ret = OB_ERR_UNEXPECTED;
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        LOG_WARN("get unexpected null ptr", K(cur_expr), K(ret));
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      } else if (OB_FAIL(checker.check(*cur_expr))) {
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        LOG_WARN("failed to check expr", K(cur_expr), K(ret));
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      } else {/*do nothing*/}
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    }
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  }
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  return ret;
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}
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int ObLogLimit::get_plan_item_info(PlanText &plan_text,
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                                   ObSqlPlanItem &plan_item)
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{
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  int ret = OB_SUCCESS;
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  if (OB_FAIL(ObLogicalOperator::get_plan_item_info(plan_text, plan_item))) {
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    LOG_WARN("failed to get plan item info", K(ret));
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  } else if (NULL != limit_expr_ || NULL != offset_expr_ ||  NULL != percent_expr_) {
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    BEGIN_BUF_PRINT;
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    ObRawExpr *limit = limit_expr_;
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    ObRawExpr *offset = offset_expr_;
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    ObRawExpr *percent = percent_expr_;
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    EXPLAIN_PRINT_EXPR(limit, type);
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    ret = BUF_PRINTF(", ");
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    EXPLAIN_PRINT_EXPR(offset, type);
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    if (percent_expr_ != NULL) {
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      BUF_PRINTF(", ");
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      EXPLAIN_PRINT_EXPR(percent, type);
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    }
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    if (is_fetch_with_ties_) {
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      BUF_PRINTF(", ");
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      BUF_PRINTF("with_ties(%s)", "true");
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    }
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    END_BUF_PRINT(plan_item.special_predicates_,
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                  plan_item.special_predicates_len_);
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  }
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  return ret;
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}
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int ObLogLimit::inner_replace_op_exprs(ObRawExprReplacer &replacer)
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{
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  int ret = OB_SUCCESS;
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  if (NULL != limit_expr_ && OB_FAIL(replace_expr_action(replacer, limit_expr_))) {
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    LOG_WARN("failed to replace limit expr", K(ret));
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  } else if (NULL != offset_expr_ && OB_FAIL(replace_expr_action(replacer, offset_expr_))) {
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    LOG_WARN("failed to replace offset expr", K(ret));
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  } else if (NULL != percent_expr_ && OB_FAIL(replace_expr_action(replacer, percent_expr_))) {
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    LOG_WARN("failed to replace percent expr", K(ret));
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  }
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  for (int64_t i = 0; OB_SUCC(ret) && i < order_items_.count(); ++i) {
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    if (OB_ISNULL(order_items_.at(i).expr_)) {
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      ret = OB_ERR_UNEXPECTED;
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      LOG_WARN("get unexpected null ", K(ret));
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    } else if (OB_FAIL(replace_expr_action(replacer, order_items_.at(i).expr_))) {
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      LOG_WARN("failed to adjust order expr with onetime", K(ret));
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    }
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  }
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  return ret;
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}
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