Details
Description
The following query returns a different execution plan and a significantly different execution time. The following repro is exactly same as the initial bug report in MENT.
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MariaDB [sysbench]> explain select a.* from sysbench.sbtest1 a left join sysbench2.sbtest1 as b on a.id = b.id where a.id = 1000 order by b.id; |
+------+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
|
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
|
+------+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
|
| 1 | SIMPLE | a | const | PRIMARY | PRIMARY | 4 | const | 1 | | |
| 1 | SIMPLE | b | const | PRIMARY | PRIMARY | 4 | const | 1 | Using index | |
+------+-------------+-------+-------+---------------+---------+---------+-------+------+-------------+
|
2 rows in set (0.000 sec) |
|
MariaDB [sysbench]> explain select a.* from sysbench.sbtest1 a left join sysbench2.sbtest1 as b on a.id = b.id where a.id in ( 1000, 1000) order by b.id; |
+------+-------------+-------+--------+---------------+---------+---------+---------------+------+----------------------------------------------+
|
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
|
+------+-------------+-------+--------+---------------+---------+---------+---------------+------+----------------------------------------------+
|
| 1 | SIMPLE | a | range | PRIMARY | PRIMARY | 4 | NULL | 1 | Using where; Using temporary; Using filesort | |
| 1 | SIMPLE | b | eq_ref | PRIMARY | PRIMARY | 4 | sysbench.a.id | 1 | Using index | |
+------+-------------+-------+--------+---------------+---------+---------+---------------+------+----------------------------------------------+
|
2 rows in set (0.000 sec) |
|
Attachments
Issue Links
- causes
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MDEV-29895 prepared view crash server (unit.conc_view)
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- Closed
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