~drizzle-trunk/drizzle/development

/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008-2009 Sun Microsystems

 *

 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

/**

 * @file

 *

 * Defines the JoinTable class which is the primary class

 * used in the nested loops join implementation.

 */

#ifndef DRIZZLED_TABLE_REFERENCE_H

#define DRIZZLED_TABLE_REFERENCE_H

#include <drizzled/base.h>

#include "drizzled/definitions.h"

namespace drizzled

{

class StoredKey;

class Item;

struct table_reference_st

{

  bool key_err;

  uint32_t key_parts; /**< num of key parts */

  uint32_t key_length; /**< length of key_buff */

  int32_t key; /**< key no (index) */

  unsigned char *key_buff; /**< value to look for with key */

  unsigned char *key_buff2; /**< key_buff+key_length */

  StoredKey **key_copy; /**< No idea what this does... */

  Item **items; /**< val()'s for each keypart */

  /**

    Array of pointers to trigger variables. Some/all of the pointers may be

    NULL.  The ref access can be used iff

      for each used key part i, (!cond_guards[i] || *cond_guards[i])

    This array is used by subquery code. The subquery code may inject

    triggered conditions, i.e. conditions that can be 'switched off'. A ref

    access created from such condition is not valid when at least one of the

    underlying conditions is switched off (see subquery code for more details)

  */

  bool **cond_guards;

  /**

    (null_rejecting & (1<<i)) means the condition is '=' and no matching

    rows will be produced if items[i] IS NULL (see add_not_null_conds())

  */

  key_part_map  null_rejecting;

  table_map	depend_map; /**< Table depends on these tables. */

  /** null byte position in the key_buf. Used for REF_OR_NULL optimization */

  unsigned char *null_ref_key;

  /**

    true <=> disable the "cache" as doing lookup with the same key value may

    produce different results (because of Index Condition Pushdown)

  */

  bool disable_cache;

};

} /* namespace drizzled */

#endif /* DRIZZLED_TABLE_REFERENCE_H */