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MDEV-18553: MDEV-16327 pre-requisits part 1: isolation of LIMIT/OFFSET handling

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This commit is contained in:
Oleksandr Byelkin
2019-09-26 09:49:50 +02:00
parent 8336371441
commit eb0804ef5e
18 changed files with 198 additions and 154 deletions
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80
sql/sql_limit.h Normal file
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/* Copyright (c) 2019, MariaDB Corporation.
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 02110-1335 USA */
#ifndef INCLUDES_MARIADB_SQL_LIMIT_H
#define INCLUDES_MARIADB_SQL_LIMIT_H
/**
LIMIT/OFFSET parameters for execution.
*/
class Select_limit_counters
{
ha_rows offset_limit_cnt_start,
select_limit_cnt, offset_limit_cnt;
public:
Select_limit_counters():
offset_limit_cnt_start(0),
select_limit_cnt(0), offset_limit_cnt(0)
{};
void set_limit(ha_rows limit, ha_rows offset)
{
offset_limit_cnt_start= offset;
select_limit_cnt= limit;
if (select_limit_cnt + offset_limit_cnt_start >=
select_limit_cnt)
select_limit_cnt+= offset_limit_cnt_start;
else
select_limit_cnt= HA_POS_ERROR;
reset();
}
void set_single_row()
{
offset_limit_cnt= offset_limit_cnt_start= 0;
select_limit_cnt= 1;
}
void reset()
{
offset_limit_cnt= offset_limit_cnt_start;
}
bool is_unlimited()
{ return select_limit_cnt == HA_POS_ERROR; }
void set_unlimited()
{ select_limit_cnt= HA_POS_ERROR; offset_limit_cnt= 0; }
bool check_and_move_offset()
{
if (offset_limit_cnt)
{
offset_limit_cnt--;
return TRUE;
}
return FALSE;
}
void remove_offset() { offset_limit_cnt= 0; }
ha_rows get_select_limit()
{ return select_limit_cnt; }
ha_rows get_offset_limit()
{ return offset_limit_cnt; }
};
#endif // INCLUDES_MARIADB_SQL_LIMIT_H