mariadb/sql/ha_federated.h

/* Copyright (C) 2003 MySQL AB

  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; either version 2 of the License, or
  (at your option) any later version.

  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*
  Please read ha_exmple.cc before reading this file.
  Please keep in mind that the federated storage engine implements all methods
  that are required to be implemented. handler.h has a full list of methods
  that you can implement.
*/

#ifdef __GNUC__
#pragma interface			/* gcc class implementation */
#endif

#include <mysql.h>
//#include <client.h>

/*
  FEDERATED_SHARE is a structure that will be shared amoung all open handlers
  The example implements the minimum of what you will probably need.
*/
typedef struct st_federated_share {
  char *table_name;
  char *table_base_name;
  /* 
    the primary select query to be used in rnd_init
  */
  char *select_query;
  /*
    remote host info, parse_url supplies
  */
  char *scheme;
  char *hostname;
  char *username;
  char *password;
  char *database;
  char *table;
  char *socket;
  char *sport;
  int port;
  uint table_name_length,table_base_name_length,use_count;
  pthread_mutex_t mutex;
  THR_LOCK lock;
} FEDERATED_SHARE;

/*
  Class definition for the storage engine
*/
class ha_federated: public handler
{
  THR_LOCK_DATA lock;      /* MySQL lock */
  FEDERATED_SHARE *share;    /* Shared lock info */
  MYSQL *mysql;
  MYSQL_RES *result;
  bool scan_flag;
  uint ref_length;
  uint fetch_num; // stores the fetch num
  MYSQL_ROW_OFFSET current_position;  // Current position used by ::position()

private:
  /*
      return 0 on success
      return errorcode otherwise
  */
  uint convert_row_to_internal_format(byte *buf, MYSQL_ROW row);
  bool create_where_from_key(String *to, KEY *key_info, 
                             const byte *key, uint key_length); 

public:
  ha_federated(TABLE *table): handler(table),
    mysql(0), result(0), scan_flag(0), 
    ref_length(sizeof(MYSQL_ROW_OFFSET)), current_position(0)
  {
  }
  ~ha_federated()
  {
  }
  /* The name that will be used for display purposes */
  const char *table_type() const { return "FEDERATED"; }
  /*
    The name of the index type that will be used for display
    don't implement this method unless you really have indexes
   */
  const char *index_type(uint inx) { return "REMOTE"; }
  const char **bas_ext() const;
  /*
    This is a list of flags that says what the storage engine
    implements. The current table flags are documented in
    handler.h
    Serg: Double check these (Brian)
    // FIX add blob support
  */
  ulong table_flags() const
  {
    return (HA_TABLE_SCAN_ON_INDEX | HA_NOT_EXACT_COUNT |
            HA_PRIMARY_KEY_IN_READ_INDEX | HA_FILE_BASED |
            HA_AUTO_PART_KEY | HA_CAN_INDEX_BLOBS);
  }
  /*
    This is a bitmap of flags that says how the storage engine
    implements indexes. The current index flags are documented in
    handler.h. If you do not implement indexes, just return zero
    here.

    part is the key part to check. First key part is 0
    If all_parts it's set, MySQL want to know the flags for the combined
    index up to and including 'part'.
  */
  ulong index_flags(uint inx, uint part, bool all_parts) const
  {
    return (HA_READ_NEXT);
    // return (HA_READ_NEXT | HA_ONLY_WHOLE_INDEX);
  }
  uint max_supported_record_length() const { return HA_MAX_REC_LENGTH; }
  uint max_supported_keys()          const { return MAX_KEY; }
  uint max_supported_key_parts()     const { return 1024; }
  uint max_supported_key_length()    const { return 1024; }
  /*
    Called in test_quick_select to determine if indexes should be used.
  */
  virtual double scan_time()
  {
    DBUG_PRINT("ha_federated::scan_time",
               ("rows %d", records)); return (double)(records*2); 
  }
  /*
    The next method will never be called if you do not implement indexes.
  */
  virtual double read_time(uint index, uint ranges, ha_rows rows) 
  { return (double) rows /  20.0+1; }

  /*
    Everything below are methods that we implment in ha_federated.cc.

    Most of these methods are not obligatory, skip them and
    MySQL will treat them as not implemented
  */
  int open(const char *name, int mode, uint test_if_locked);    // required
  int close(void);                                              // required

  int write_row(byte * buf);
  int update_row(const byte * old_data, byte * new_data);
  int delete_row(const byte * buf);
  int index_init(uint keynr);
  int index_read(byte * buf, const byte * key,
                 uint key_len, enum ha_rkey_function find_flag);
  int index_read_idx(byte * buf, uint idx, const byte * key,
                     uint key_len, enum ha_rkey_function find_flag);
  int index_next(byte * buf);
  int index_end();
  /*
    unlike index_init(), rnd_init() can be called two times
    without rnd_end() in between (it only makes sense if scan=1).
    then the second call should prepare for the new table scan
    (e.g if rnd_init allocates the cursor, second call should
    position it to the start of the table, no need to deallocate
    and allocate it again
  */
  int rnd_init(bool scan);                                      //required
  int rnd_end();
  int rnd_next(byte *buf);                                      //required
  int rnd_pos(byte * buf, byte *pos);                           //required
  void position(const byte *record);                            //required
  void info(uint);                                              //required

  int delete_all_rows(void);
  int create(const char *name, TABLE *form,
             HA_CREATE_INFO *create_info);                      //required

  THR_LOCK_DATA **store_lock(THD *thd, THR_LOCK_DATA **to,
                             enum thr_lock_type lock_type);     //required
};

bool federated_db_init(void);
bool federated_db_end(void);