/* - 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 JOIN_TAB class which is the primary class
 * used in the nested loops join implementation.
 */

#ifndef DRIZZLED_JOIN_TAB_H
#define DRIZZLED_JOIN_TAB_H

typedef struct st_join_table 
{
  st_join_table() {}                          /* Remove gcc warning */
  Table *table;
  KEYUSE *keyuse;			/**< pointer to first used key */
  SQL_SELECT *select;
  COND *select_cond;
  QUICK_SELECT_I *quick;
  /*
    The value of select_cond before we've attempted to do Index Condition
    Pushdown. We may need to restore everything back if we first choose one
    index but then reconsider (see test_if_skip_sort_order() for such
    scenarios).
    NULL means no index condition pushdown was performed.
  */
  Item *pre_idx_push_select_cond;
  Item **on_expr_ref;   /**< pointer to the associated on expression   */
  COND_EQUAL *cond_equal;    /**< multiple equalities for the on expression */
  st_join_table *first_inner;   /**< first inner table for including outerjoin */
  bool found;         /**< true after all matches or null complement */
  bool not_null_compl;/**< true before null complement is added      */
  st_join_table *last_inner;    /**< last table table for embedding outer join */
  st_join_table *first_upper;  /**< first inner table for embedding outer join */
  st_join_table *first_unmatched; /**< used for optimization purposes only     */

  /* Special content for EXPLAIN 'Extra' column or NULL if none */
  const char *info;
  /*
    Bitmap of TAB_INFO_* bits that encodes special line for EXPLAIN 'Extra'
    column, or 0 if there is no info.
  */
  uint32_t packed_info;

  Read_record_func read_first_record;
  Next_select_func next_select;
  READ_RECORD	read_record;
  /*
    Currently the following two fields are used only for a [NOT] IN subquery
    if it is executed by an alternative full table scan when the left operand of
    the subquery predicate is evaluated to NULL.
  */
  Read_record_func save_read_first_record;/* to save read_first_record */
  int (*save_read_record) (READ_RECORD *);/* to save read_record.read_record */
  double worst_seeks;
  key_map	const_keys;			/**< Keys with constant part */
  key_map	checked_keys;			/**< Keys checked in find_best */
  key_map	needed_reg;
  key_map keys;                           /**< all keys with can be used */

  /* Either #rows in the table or 1 for const table.  */
  ha_rows	records;
  /*
    Number of records that will be scanned (yes scanned, not returned) by the
    best 'independent' access method, i.e. table scan or QUICK_*_SELECT)
  */
  ha_rows found_records;
  /*
    Cost of accessing the table using "ALL" or range/index_merge access
    method (but not 'index' for some reason), i.e. this matches method which
    E(#records) is in found_records.
  */
  ha_rows read_time;

  table_map	dependent,key_dependent;
  uint32_t use_quick,index;
  uint32_t status;				///< Save status for cache
  uint		used_fields,used_fieldlength,used_blobs;
  enum join_type type;
  bool		cached_eq_ref_table,eq_ref_table,not_used_in_distinct;
  /* true <=> index-based access method must return records in order */
  bool		sorted;
  /*
    If it's not 0 the number stored this field indicates that the index
    scan has been chosen to access the table data and we expect to scan
    this number of rows for the table.
  */
  ha_rows limit;
  TABLE_REF	ref;
  JOIN_CACHE cache;
  JOIN *join;
  /** Bitmap of nested joins this table is part of */

  /* SemiJoinDuplicateElimination variables: */
  /*
    Embedding SJ-nest (may be not the direct parent), or NULL if none.
    This variable holds the result of table pullout.
  */
  TableList *emb_sj_nest;

  /* Variables for semi-join duplicate elimination */
  SJ_TMP_TABLE *flush_weedout_table;
  SJ_TMP_TABLE *check_weed_out_table;
  struct st_join_table *do_firstmatch;

  /*
     ptr  - this join tab should do an InsideOut scan. Points
            to the tab for which we'll need to check tab->found_match.

     NULL - Not an insideout scan.
  */
  struct st_join_table *insideout_match_tab;
  unsigned char *insideout_buf; // Buffer to save index tuple to be able to skip dups

  /* Used by InsideOut scan. Just set to true when have found a row. */
  bool found_match;

  enum {
    /* If set, the rowid of this table must be put into the temptable. */
    KEEP_ROWID=1,
    /*
      If set, one should call h->position() to obtain the rowid,
      otherwise, the rowid is assumed to already be in h->ref
      (this is because join caching and filesort() save the rowid and then
      put it back into h->ref)
    */
    CALL_POSITION=2
  };
  /* A set of flags from the above enum */
  int rowid_keep_flags;

  /* NestedOuterJoins: Bitmap of nested joins this table is part of */
  nested_join_map embedding_map;

  void cleanup();
  inline bool is_using_loose_index_scan()
  {
    return (select && select->quick &&
            (select->quick->get_type() ==
             QUICK_SELECT_I::QS_TYPE_GROUP_MIN_MAX));
  }
} JOIN_TAB;

#endif /* DRIZZLED_JOIN_TAB_H */