mariadb-columnstore-engine/dbcon/mysql/ha_mcs_pushdown.h

/*
   Copyright (c) 2019-20 MariaDB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */


#ifndef HA_MCS_PUSH
#define HA_MCS_PUSH

#include "idb_mysql.h"
#include "ha_mcs.h"
#include "ha_mcs_sysvars.h"
#define NEED_CALPONT_EXTERNS
#include "ha_mcs_impl.h"
#include "ha_mcs_impl_if.h"
#include "ha_mcs_opt_rewrites.h"

void mutate_optimizer_flags(THD *thd_);
void restore_optimizer_flags(THD *thd_);

enum mcs_handler_types_t
{
    SELECT,
    DERIVED,
    GROUP_BY,
    LEGACY
};

struct mcs_handler_info
{
    mcs_handler_info() : hndl_ptr(NULL), hndl_type(LEGACY) { };
    mcs_handler_info(mcs_handler_types_t type) : hndl_ptr(NULL), hndl_type(type) { };
    mcs_handler_info(void* ptr, mcs_handler_types_t type) : hndl_ptr(ptr), hndl_type(type) { };
    ~mcs_handler_info() { };
    void* hndl_ptr;
    mcs_handler_types_t hndl_type;
};

/*@brief  group_by_handler class*/
/***********************************************************
 * DESCRIPTION:
 * Provides server with group_by_handler API methods.
 * One should read comments in server/sql/group_by_handler.h
 * Attributes:
 * select - attribute contains all GROUP BY, HAVING, ORDER items and calls it
 *              an extended SELECT list according to comments in
 *              server/sql/group_handler.cc.
 *              So the temporary table for
 *              select count(*) from b group by a having a > 3 order by a
 *              will have 4 columns not 1.
 *              However server ignores all NULLs used in
 *              GROUP BY, HAVING, ORDER.
 * select_list_descr - contains Item description returned by Item->print()
 *              that is used in lookup for corresponding columns in
 *              extended SELECT list.
 * table_list - contains all tables involved. Must be CS tables only.
 * distinct - looks like a useless thing for now. Couldn't get it set by server.
 * where - where items.
 * group_by - group by ORDER items.
 * order_by - order by ORDER items.
 * having - having Item.
 * Methods:
 * init_scan - get plan and send it to ExeMgr. Get the execution result.
 * next_row - get a row back from sm.
 * end_scan - finish and clean the things up.
 ***********************************************************/
class ha_mcs_group_by_handler: public group_by_handler
{
public:
    ha_mcs_group_by_handler(THD* thd_arg, Query* query);
    ~ha_mcs_group_by_handler();
    int init_scan() override;
    int next_row() override;
    int end_scan() override;

    List<Item>* select;
    TABLE_LIST* table_list;
    bool        distinct;
    Item*       where;
    ORDER*      group_by;
    ORDER*      order_by;
    Item*       having;
};

/*@brief  derived_handler class*/
/***********************************************************
 * DESCRIPTION:
 * derived_handler API methods. Could be used by the server
 * tp process sub-queries.
 * More details in server/sql/dervied_handler.h
 * COLUMNSTORE_SHARE* hton share
 * tbl in the constructor is the list of the tables involved.
 * Methods:
 * init_scan - get plan and send it to ExeMgr. Get the execution result.
 * next_row - get a row back from sm.
 * end_scan - finish and clean the things up.
 ***********************************************************/
class ha_columnstore_derived_handler: public derived_handler
{
private:
  COLUMNSTORE_SHARE *share;

public:
  ha_columnstore_derived_handler(THD* thd_arg, TABLE_LIST *tbl);
  ~ha_columnstore_derived_handler();
  int init_scan() override;
  int next_row() override;
  int end_scan() override;
  void print_error(int, unsigned long);
};

/*@brief select_handler class*/
/***********************************************************
 * DESCRIPTION:
 * select_handler API methods. Could be used by the server
 * tp pushdown the whole query described by SELECT_LEX.
 * More details in server/sql/select_handler.h
 * COLUMNSTORE_SHARE* hton share
 * sel in the constructor is the semantic tree for the query.
 * Methods:
 * init_scan - get plan and send it to ExeMgr. Get the execution result.
 * next_row - get a row back from sm.
 * end_scan - finish and clean the things up.
 ***********************************************************/
class ha_columnstore_select_handler: public select_handler
{
private:
  COLUMNSTORE_SHARE *share;

public:
  bool rewrite_error;
  std::string err_msg;
  ha_columnstore_select_handler(THD* thd_arg, SELECT_LEX* sel);
  ~ha_columnstore_select_handler();
  int init_scan() override;
  int next_row() override;
  int end_scan() override;
};

#endif