range.h

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
 *
 *  Copyright (C) 2008-2009 Sun Microsystems, Inc.
 *
 *  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
 */

/* classes to use when handling where clause */

#pragma once

#include <drizzled/field.h>
#include <drizzled/item/sum.h>
#include <drizzled/table_reference.h>

#include <queue>

#include <boost/dynamic_bitset.hpp>

namespace drizzled {

typedef struct st_key_part
{
  uint16_t key;
  uint16_t part;
  /* See KeyPartInfo for meaning of the next two: */
  uint16_t store_length;
  uint16_t length;
  uint8_t null_bit;
  uint8_t flag;
  Field *field;
} KEY_PART;


namespace optimizer {

class QuickSelectInterface
{
public:
  bool sorted;
  ha_rows records; 
  double read_time; 
  Table *head;
  uint32_t index;
  uint32_t max_used_key_length;
  uint32_t used_key_parts;
  unsigned char *last_rowid;

  unsigned char *record;

  QuickSelectInterface();
  virtual ~QuickSelectInterface(){};

  virtual int init() = 0;

  virtual int reset(void) = 0;
  virtual int get_next() = 0;

  virtual void range_end() {}

  virtual bool reverse_sorted() const = 0;

  virtual bool unique_key_range() const
  {
    return false;
  }

  enum 
  {
    QS_TYPE_RANGE= 0,
    QS_TYPE_INDEX_MERGE= 1,
    QS_TYPE_RANGE_DESC= 2,
    QS_TYPE_ROR_INTERSECT= 4,
    QS_TYPE_ROR_UNION= 5,
    QS_TYPE_GROUP_MIN_MAX= 6
  };

  virtual int get_type() const = 0;

  virtual int init_ror_merged_scan(bool)
  {
    assert(0);
    return 1;
  }

  virtual void save_last_pos(){};

  virtual void add_keys_and_lengths(std::string *key_names,
                                    std::string *used_lengths)=0;

  virtual void add_info_string(std::string *)
  {}

  virtual bool is_keys_used(const boost::dynamic_bitset<>& fields);
};

typedef struct st_quick_range_seq_ctx
{
  QuickRange **first;
  QuickRange **cur;
  QuickRange **last;
} QuickRangeSequenceContext;

range_seq_t quick_range_seq_init(void *init_param, uint32_t n_ranges, uint32_t flags);

uint32_t quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);

class SqlSelect : public memory::SqlAlloc 
{
 public:
  QuickSelectInterface *quick; 
  COND *cond; 
  Table *head;
  internal::io_cache_st *file; 
  ha_rows records; 
  double read_time; 
  key_map quick_keys; 
  key_map needed_reg; 
  table_map const_tables;
  table_map read_tables;
  bool free_cond;

  SqlSelect();
  ~SqlSelect();
  void cleanup();
  bool check_quick(Session *session, bool force_quick_range, ha_rows limit);
  bool skip_record();
  int test_quick_select(Session *session, key_map keys, table_map prev_tables,
                        ha_rows limit, bool force_quick_range,
                        bool ordered_output);
};

QuickRangeSelect *get_quick_select_for_ref(Session *session, 
                                           Table *table,
                                           table_reference_st *ref,
                                           ha_rows records);

/*
  Create a QuickRangeSelect from given key and SEL_ARG tree for that key.

  SYNOPSIS
    get_quick_select()
      param
      idx            Index of used key in param->key.
      key_tree       SEL_ARG tree for the used key
      mrr_flags      MRR parameter for quick select
      mrr_buf_size   MRR parameter for quick select
      parent_alloc   If not NULL, use it to allocate memory for
                     quick select data. Otherwise use quick->alloc.
  NOTES
    The caller must call QUICK_SELECT::init for returned quick select.

    CAUTION! This function may change session->mem_root to a memory::Root which will be
    deallocated when the returned quick select is deleted.

  RETURN
    NULL on error
    otherwise created quick select
*/
QuickRangeSelect *get_quick_select(Parameter *param,
                                   uint32_t index,
                                   SEL_ARG *key_tree, 
                                   uint32_t mrr_flags,
                                   uint32_t mrr_buf_size, 
                                   memory::Root *alloc);

uint32_t get_index_for_order(Table *table, Order *order, ha_rows limit);

SqlSelect *make_select(Table *head, 
                       table_map const_tables,
                       table_map read_tables, 
                       COND *conds,
                       bool allow_null_cond,
                       int *error);

bool get_quick_keys(Parameter *param, 
                    QuickRangeSelect *quick,
                    KEY_PART *key,
                    SEL_ARG *key_tree, 
                    unsigned char *min_key,
                    uint32_t min_key_flag,
                    unsigned char *max_key,
                    uint32_t max_key_flag);

} /* namespace optimizer */

} /* namespace drizzled */