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f36ca142f7
Prototype change: - virtual ha_rows records_in_range(uint inx, key_range *min_key, - key_range *max_key) + virtual ha_rows records_in_range(uint inx, const key_range *min_key, + const key_range *max_key, + page_range *res) The handler can ignore the page_range parameter. In the case the handler updates the parameter, the optimizer can deduce the following: - If previous range's last key is on the same block as next range's first key - If the current key range is in one block - We can also assume that the first and last block read are cached! This can be used for a better calculation of IO seeks when we estimate the cost of a range index scan. The parameter is fully implemented for MyISAM, Aria and InnoDB. A separate patch will update handler::multi_range_read_info_const() to take the benefits of this change and also remove the double records_in_range() calls that are not anymore needed.
43 lines
1.5 KiB
C
43 lines
1.5 KiB
C
/* Copyright (c) 2002, 2004-2006 MySQL AB
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Use is subject to license terms
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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 Street, Fifth Floor, Boston, MA 02110-1335 USA */
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#include "myrg_def.h"
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ha_rows myrg_records_in_range(MYRG_INFO *info, int inx,
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const key_range *min_key,
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const key_range *max_key,
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page_range *pages)
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{
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ha_rows records=0, res;
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MYRG_TABLE *table;
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page_range ignore_pages;
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/* Don't calculate pages of more than one active partition */
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if (info->open_tables +1 != info->end_table)
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pages= &ignore_pages;
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for (table=info->open_tables ; table != info->end_table ; table++)
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{
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res= mi_records_in_range(table->table, inx, min_key, max_key, pages);
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if (res == HA_POS_ERROR)
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return HA_POS_ERROR;
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if (records > HA_POS_ERROR - res)
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return HA_POS_ERROR-1;
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records+=res;
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}
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return records;
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}
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