rules.h

/* Copyright (c) 2021 OceanBase and/or its affiliates. All rights reserved.
miniob is licensed under Mulan PSL v2.
You can use this software according to the terms and conditions of the Mulan PSL v2.
You may obtain a copy of Mulan PSL v2 at:
         http://license.coscl.org.cn/MulanPSL2
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 PSL v2 for more details. */
 
#pragma once
 
#include "common/lang/unordered_map.h"
#include "sql/optimizer/cascade/optimizer_context.h"
#include "sql/optimizer/cascade/pattern.h"
 
enum class RuleType : uint32_t
{
  // Transformation rules (logical -> logical)
  // TODO: currently, we don't have transformation rules
 
  // Don't move this one
  LogicalPhysicalDelimiter,
 
  // Implementation rules (logical -> physical)
  GET_TO_SEQ_SCAN,
  GET_TO_INDEX_SCAN,
  DELETE_TO_PHYSICAL,
  UPDATE_TO_PHYSICAL,
  INSERT_TO_PHYSICAL,
  AGGREGATE_TO_PHYSICAL,
  INNER_JOIN_TO_NL_JOIN,
  INNER_JOIN_TO_HASH_JOIN,
  IMPLEMENT_LIMIT,
  PROJECTION_TO_PHYSOCAL,
  ANALYZE_TO_PHYSICAL,
  EXPLAIN_TO_PHYSICAL,
  CALC_TO_PHYSICAL,
  PREDICATE_TO_PHYSICAL,
  GROUP_BY_TO_PHYSICAL_AGGREGATION,
  GROUP_BY_TO_PHYSICL_HASH_GROUP_BY,
 
  NUM_RULES
};
 
enum class RuleSetName : uint32_t
{
  // TODO: add more rule sets
  PHYSICAL_IMPLEMENTATION
};
 
enum class RulePromise : uint32_t
{
 
  LOGICAL_PROMISE = 0,
 
  PHYSICAL_PROMISE = 1
};
 
class Rule
{
public:
  virtual ~Rule() {}
  Pattern *get_match_pattern() const { return match_pattern_.get(); }
 
  bool is_physical() const { return type_ > RuleType::LogicalPhysicalDelimiter; }
 
  bool is_logical() const { return type_ < RuleType::LogicalPhysicalDelimiter; }
 
  RuleType get_type() { return type_; }
 
  uint32_t get_rule_idx() { return static_cast<uint32_t>(type_); }
 
  virtual RulePromise promise(GroupExpr *group_expr) const
  {
    if (is_physical())
      return RulePromise::PHYSICAL_PROMISE;
    return RulePromise::LOGICAL_PROMISE;
  }
 
  virtual void transform(OperatorNode *input, std::vector<std::unique_ptr<OperatorNode>> *transformed,
      OptimizerContext *context) const = 0;
 
protected:
  RuleType            type_;
  unique_ptr<Pattern> match_pattern_;
};
 
class RuleWithPromise
{
public:
  RuleWithPromise(Rule *rule, RulePromise promise) : rule_(rule), promise_(promise) {}
 
  Rule *get_rule() { return rule_; }
 
  RulePromise get_promise() { return promise_; }
 
  bool operator<(const RuleWithPromise &r) const { return promise_ < r.promise_; }
 
  bool operator>(const RuleWithPromise &r) const { return promise_ > r.promise_; }
 
private:
  Rule *rule_;
 
  RulePromise promise_;
};
 
class RuleSet
{
public:
  RuleSet();
 
  ~RuleSet()
  {
    for (auto &it : rules_map_) {
      for (auto rule : it.second) {
        delete rule;
      }
    }
  }
 
  void add_rule(RuleSetName set, Rule *rule) { rules_map_[static_cast<uint32_t>(set)].push_back(rule); }
 
  std::vector<Rule *> &get_rules_by_name(RuleSetName set) { return rules_map_[static_cast<uint32_t>(set)]; }
 
private:
  std::unordered_map<uint32_t, std::vector<Rule *>> rules_map_;
};