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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
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* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
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* Copyright (C) 2008-2009 Sun Microsystems
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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#ifndef DRIZZLED_OPTIMIZER_QUICK_RANGE_SELECT_H
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#define DRIZZLED_OPTIMIZER_QUICK_RANGE_SELECT_H
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#include "drizzled/optimizer/range.h"
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* Quick select that does a range scan on a single key.
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* The records are returned in key order.
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class QuickRangeSelect : public QuickSelectInterface
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DYNAMIC_ARRAY ranges; /**< ordered array of range ptrs */
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/** Members to deal with case when this quick select is a ROR-merged scan */
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bool in_ror_merged_scan;
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MyBitmap column_bitmap;
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MyBitmap *save_read_set;
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MyBitmap *save_write_set;
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bool free_file; /**< True when this->file is "owned" by this quick select */
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/* Range pointers to be used when not using MRR interface */
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QuickRange **cur_range; /**< current element in ranges */
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QuickRange *last_range;
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/** Members needed to use the MRR interface */
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QuickRangeSequenceContext qr_traversal_ctx;
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uint32_t mrr_buf_size; /**< copy from session->variables.read_rnd_buff_size */
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HANDLER_BUFFER *mrr_buf_desc; /**< the Cursor buffer */
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/** Info about index we're scanning */
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KEY_PART_INFO *key_part_info;
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bool dont_free; /**< Used by QuickSelectDescending */
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* Compare if found key is over max-value
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* @return 0 if key <= range->max_key
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* @todo: Figure out why can't this function be as simple as cmp_prev().
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int cmp_next(QuickRange *range);
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* @return 0 if found key is inside range (found key >= range->min_key).
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int cmp_prev(QuickRange *range);
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* Check if current row will be retrieved by this QuickRangeSelect
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* It is assumed that currently a scan is being done on another index
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* which reads all necessary parts of the index that is scanned by this
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* The implementation does a binary search on sorted array of disjoint
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* ranges, without taking size of range into account.
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* This function is used to filter out clustered PK scan rows in
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* index_merge quick select.
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* @retval true if current row will be retrieved by this quick select
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uint32_t mrr_flags; /**< Flags to be used with MRR interface */
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QuickRangeSelect(Session *session,
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MEM_ROOT *parent_alloc,
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* Get next possible record using quick-struct.
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* QuickRangeSelect::get_next()
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* Record is read into table->record[0]
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* @retval 0 Found row
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* @retval HA_ERR_END_OF_FILE No (more) rows in range
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* @retaval # Error code
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* Get the next record with a different prefix.
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* QuickRangeSelect::get_next_prefix()
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* @param[in] prefix_length length of cur_prefix
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* @param[in] cur_prefix prefix of a key to be searched for
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* Each subsequent call to the method retrieves the first record that has a
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* prefix with length prefix_length different from cur_prefix, such that the
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* record with the new prefix is within the ranges described by
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* this->ranges. The record found is stored into the buffer pointed by
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* The method is useful for GROUP-BY queries with range conditions to
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* discover the prefix of the next group that satisfies the range conditions.
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* This method is a modified copy of QuickRangeSelect::get_next(), so both
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* methods should be unified into a more general one to reduce code
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* @retval 0 on success
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* @retval HA_ERR_END_OF_FILE if returned all keys
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* @retval other if some error occurred
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int get_next_prefix(uint32_t prefix_length,
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key_part_map keypart_map,
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unsigned char *cur_prefix);
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bool reverse_sorted()
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* @return true if there is only one range and this uses the whole primary key
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bool unique_key_range();
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* Initialize this quick select to be a ROR-merged scan.
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* QuickRangeSelect::init_ror_merged_scan()
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* @param[in] reuse_handler If true, use head->cursor, otherwise create a separate Cursor object
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* This function creates and prepares for subsequent use a separate Cursor
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* object if it can't reuse head->cursor. The reason for this is that during
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* ROR-merge several key scans are performed simultaneously, and a single
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* Cursor is only capable of preserving context of a single key scan.
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* In ROR-merge the quick select doing merge does full records retrieval,
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* merged quick selects read only keys.
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* @reval 0 ROR child scan initialized, ok to use.
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int init_ror_merged_scan(bool reuse_handler);
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void save_last_pos();
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return QS_TYPE_RANGE;
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void add_keys_and_lengths(String *key_names, String *used_lengths);
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void add_info_string(String *str);
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/* Used only by QuickSelectDescending */
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QuickRangeSelect(const QuickRangeSelect& org) : QuickSelectInterface()
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memmove(this, &org, sizeof(*this));
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Use default MRR implementation for reverse scans. No table engine
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currently can do an MRR scan with output in reverse index order.
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mrr_flags|= HA_MRR_USE_DEFAULT_IMPL;
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friend class ::TRP_ROR_INTERSECT;
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QuickRangeSelect *get_quick_select_for_ref(Session *session, Table *table,
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struct table_reference_st *ref,
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friend bool get_quick_keys(Parameter *param,
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QuickRangeSelect *quick,
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unsigned char *min_key,
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uint32_t min_key_flag,
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unsigned char *max_key,
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uint32_t max_key_flag);
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friend QuickRangeSelect *get_quick_select(Parameter *,
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uint32_t mrr_buf_size,
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friend class QuickSelectDescending;
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friend class QuickIndexMergeSelect;
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friend class QUICK_ROR_INTERSECT_SELECT;
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friend class QUICK_GROUP_MIN_MAX_SELECT;
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friend uint32_t quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);
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friend range_seq_t quick_range_seq_init(void *init_param,
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friend void select_describe(JOIN *join,
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const char *message);
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class QuickSelectDescending : public QuickRangeSelect
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QuickSelectDescending(QuickRangeSelect *q,
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uint32_t used_key_parts,
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bool reverse_sorted()
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return QS_TYPE_RANGE_DESC;
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bool range_reads_after_key(QuickRange *range);
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return QuickRangeSelect::reset();
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List<QuickRange> rev_ranges;
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List_iterator<QuickRange> rev_it;
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} /* namespace optimizer */
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} /* namespace drizzled */
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#endif /* DRIZZLED_OPTIMIZER_QUICK_RANGE_SELECT_H */
added
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drizzled/optimizer/quick_range_select.h
