parse_tree_hints.h

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/* Copyright (c) 2015, 2025, Oracle and/or its affiliates.
 
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   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.
 
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.
 
   You should have received a copy of the GNU General Public License
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   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
/*
  Parse tree node classes for optimizer hint syntax
*/
 
#ifndef PARSE_TREE_HINTS_INCLUDED
#define PARSE_TREE_HINTS_INCLUDED
 
#include <sys/types.h>
 
#include "lex_string.h"
#include "my_compiler.h"
#include "sql/mem_root_array.h"
#include "sql/opt_hints.h"
#include "sql/parse_tree_node_base.h"
#include "sql/sql_show.h"
#include "sql_string.h"
 
class Item;
class THD;
struct MEM_ROOT;
 
struct Hint_param_table {
  LEX_CSTRING table;
  LEX_CSTRING opt_query_block;
};
 
typedef Mem_root_array_YY<LEX_CSTRING> Hint_param_index_list;
typedef Mem_root_array_YY<Hint_param_table> Hint_param_table_list;
 
/**
  The class is a base class for representation of the
  different types of the hints. For the complex hints
  it is also used as a container for additional arguments.
*/
class PT_hint : public Parse_tree_node {
  opt_hints_enum hint_type;  // Hint type
  bool state;                // true if hints is on, false otherwise
 public:
  PT_hint(opt_hints_enum hint_type_arg, bool switch_state_arg)
      : Parse_tree_node(POS()) /* TODO: handle position in hints */,
        hint_type(hint_type_arg),
        state(switch_state_arg) {}
 
  opt_hints_enum type() const { return hint_type; }
  bool switch_on() const { return state; }
  /**
    Print warning issuing in processing of the hint.
 
    @param thd             Pointer to THD object
    @param err_code        Error code
    @param qb_name_arg     QB name
    @param table_name_arg  table name
    @param key_name_arg    key name
    @param hint            Pointer to hint object
  */
  virtual void print_warn(THD *thd, uint err_code,
                          const LEX_CSTRING *qb_name_arg,
                          LEX_CSTRING *table_name_arg,
                          LEX_CSTRING *key_name_arg, PT_hint *hint) const;
  /**
    Append additional hint arguments.
 
    @param thd             Pointer to THD object
    @param str             Pointer to String object
  */
  virtual void append_args(const THD *thd [[maybe_unused]],
                           String *str [[maybe_unused]]) const {}
  bool supports_view() {
    /*
      Only index hints are supported to be used in views.
      Other hints can be added separately.
    */
    return (type() >= INDEX_HINT_ENUM && type() <= ORDER_INDEX_HINT_ENUM);
  }
};
 
class PT_hint_list : public Parse_tree_node {
  typedef Parse_tree_node super;
 
  Mem_root_array<PT_hint *> hints;
 
 public:
  explicit PT_hint_list(MEM_ROOT *mem_root)
      : super(POS()) /* TODO: handle position of hints */, hints(mem_root) {}
 
  /**
    Function handles list of the hints we get after
    parse procedure. It also creates query block hint
    object(Opt_hints_qb) if it does not exists.
 
    @param pc   Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
 
  bool push_back(PT_hint *hint) { return hints.push_back(hint); }
};
 
/**
  Parse tree hint object for query block level hints.
*/
class PT_qb_level_hint : public PT_hint {
  /** Name of query block. */
  const LEX_CSTRING qb_name;
  /** Bit mask of arguments to hint. */
  uint args;
  /** List of tables specified in join order hint */
  Hint_param_table_list table_list;
 
  typedef PT_hint super;
 
 public:
  PT_qb_level_hint(const LEX_CSTRING qb_name_arg, bool switch_state_arg,
                   enum opt_hints_enum hint_type_arg, uint arg)
      : PT_hint(hint_type_arg, switch_state_arg),
        qb_name(qb_name_arg),
        args(arg) {}
 
  PT_qb_level_hint(const LEX_CSTRING qb_name_arg, bool switch_state_arg,
                   enum opt_hints_enum hint_type_arg,
                   const Hint_param_table_list &table_list_arg)
      : PT_hint(hint_type_arg, switch_state_arg),
        qb_name(qb_name_arg),
        args(0),
        table_list(table_list_arg) {}
 
  uint get_args() const { return args; }
 
  /**
    Function handles query block level hint. It also creates query block hint
    object (Opt_hints_qb) if it does not exist.
 
    @param pc  Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
 
  /**
    Append hint arguments to given string
 
    @param thd             Pointer to THD object
    @param str             Pointer to String object
  */
  void append_args(const THD *thd, String *str) const override;
  virtual Hint_param_table_list *get_table_list() { return &table_list; }
};
 
/**
  Parse tree hint object for table level hints.
*/
 
class PT_table_level_hint : public PT_hint {
  const LEX_CSTRING qb_name;
  Hint_param_table_list table_list;
 
  typedef PT_hint super;
 
 public:
  PT_table_level_hint(const LEX_CSTRING qb_name_arg,
                      const Hint_param_table_list &table_list_arg,
                      bool switch_state_arg, opt_hints_enum hint_type_arg)
      : PT_hint(hint_type_arg, switch_state_arg),
        qb_name(qb_name_arg),
        table_list(table_list_arg) {}
 
  /**
    Function handles table level hint. It also creates
    table hint object (Opt_hints_table) if it does not
    exist.
 
    @param pc  Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
};
 
/**
  Parse tree hint object for key level hints.
*/
 
class PT_key_level_hint : public PT_hint {
  Hint_param_table table_name;
  Hint_param_index_list key_list;
 
  typedef PT_hint super;
 
 public:
  PT_key_level_hint(Hint_param_table &table_name_arg,
                    const Hint_param_index_list &key_list_arg,
                    bool switch_state_arg, opt_hints_enum hint_type_arg)
      : PT_hint(hint_type_arg, switch_state_arg),
        table_name(table_name_arg),
        key_list(key_list_arg) {}
 
  /**
    Function handles key level hint.
    It also creates key hint object
    (Opt_hints_key) if it does not
    exist.
 
    @param pc  Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
  void append_args(const THD *thd, String *str) const override;
};
 
/**
  Parse tree hint object for QB_NAME hint.
*/
 
class PT_hint_qb_name : public PT_hint {
  const LEX_CSTRING qb_name;
 
  typedef PT_hint super;
 
 public:
  PT_hint_qb_name(const LEX_CSTRING qb_name_arg)
      : PT_hint(QB_NAME_HINT_ENUM, true), qb_name(qb_name_arg) {}
 
  /**
    Function sets query block name.
 
    @param pc  Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
  void append_args(const THD *thd, String *str) const override {
    append_identifier(thd, str, qb_name.str, qb_name.length);
  }
};
 
/**
  Parse tree hint object for MAX_EXECUTION_TIME hint.
*/
 
class PT_hint_max_execution_time : public PT_hint {
  typedef PT_hint super;
 
 public:
  ulong milliseconds;
 
  explicit PT_hint_max_execution_time(ulong milliseconds_arg)
      : PT_hint(MAX_EXEC_TIME_HINT_ENUM, true),
        milliseconds(milliseconds_arg) {}
  /**
    Function initializes MAX_EXECUTION_TIME hint
 
    @param pc   Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
  void append_args(const THD *, String *str) const override {
    str->append_ulonglong(milliseconds);
  }
};
 
class PT_hint_sys_var : public PT_hint {
  const LEX_CSTRING sys_var_name;
  Item *sys_var_value;
 
  typedef PT_hint super;
 
 public:
  explicit PT_hint_sys_var(const LEX_CSTRING sys_var_name_arg,
                           Item *sys_var_value_arg)
      : PT_hint(MAX_HINT_ENUM, true),
        sys_var_name(sys_var_name_arg),
        sys_var_value(sys_var_value_arg) {}
  /**
    Function initializes SET_VAR hint.
 
    @param pc   Pointer to Parse_context object
 
    @return  true in case of error,
             false otherwise
  */
  bool do_contextualize(Parse_context *pc) override;
};
 
/**
  Parse tree hint object for RESOURCE_GROUP hint.
*/
 
class PT_hint_resource_group : public PT_hint {
  const LEX_CSTRING m_resource_group_name;
 
  typedef PT_hint super;
 
 public:
  PT_hint_resource_group(const LEX_CSTRING &name)
      : PT_hint(RESOURCE_GROUP_HINT_ENUM, true), m_resource_group_name(name) {}
 
  /**
    Function initializes resource group name and checks for presence of
    resource group. Also it checks for invocation of hint from stored
    routines or sub query.
 
     @param pc Pointer to Parse_context object
 
     @return true in case of error,
             false otherwise
  */
 
  bool do_contextualize(Parse_context *pc) override;
 
  /**
    Append hint arguments to given string.
 
    @param thd      Pointer to THD object.
    @param str      Pointer to String object.
  */
 
  void append_args(const THD *thd, String *str) const override {
    append_identifier(thd, str, m_resource_group_name.str,
                      m_resource_group_name.length);
  }
};
 
#endif /* PARSE_TREE_HINTS_INCLUDED */