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- Query 1 AFTER:
- A)
- PROFILE:
- mysql> show profile for query 112;
- +--------------------+----------+
- | Status | Duration |
- +--------------------+----------+
- | starting | 0.000084 |
- | Opening tables | 0.000016 |
- | System lock | 0.000005 |
- | Table lock | 0.000009 |
- | init | 0.000026 |
- | optimizing | 0.000011 |
- | statistics | 0.000030 |
- | preparing | 0.000014 |
- | executing | 0.000003 |
- | Sending data | 0.180282 |
- | end | 0.000016 |
- | query end | 0.000004 |
- | freeing items | 0.001778 |
- | logging slow query | 0.000006 |
- | cleaning up | 0.000006 |
- +--------------------+----------+
- 15 rows in set (0.00 sec)
- EXPLAIN:
- mysql> EXPLAIN SELECT SQL_NO_CACHE c.owner,p.time FROM car c, passing p
- -> WHERE p.regno=c.regno;
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------------+
- | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------------+
- | 1 | SIMPLE | p | index | PRIMARY | PRIMARY | 32 | NULL | 100000 | Using index |
- | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 10 | db.p.regno | 1 | |
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------------+
- 2 rows in set (0.00 sec)
- B)
- C)
- Profile:
- mysql> show profile for query 142;
- +--------------------+----------+
- | Status | Duration |
- +--------------------+----------+
- | starting | 0.000106 |
- | Opening tables | 0.000017 |
- | System lock | 0.000005 |
- | Table lock | 0.000009 |
- | init | 0.000028 |
- | optimizing | 0.000012 |
- | statistics | 0.000026 |
- | preparing | 0.000014 |
- | executing | 0.000003 |
- | Sending data | 0.893014 |
- | end | 0.000022 |
- | query end | 0.000003 |
- | freeing items | 0.001403 |
- | logging slow query | 0.000003 |
- | cleaning up | 0.000187 |
- +--------------------+----------+
- 15 rows in set (0.00 sec)
- Explain:
- mysql> EXPLAIN SELECT c.owner, p.time FROM car c FORCE INDEX(PRIMARY), passing p IGNORE INDEX(PRIMARY) WHERE p.regno=c.regno;
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------+
- | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------+
- | 1 | SIMPLE | p | ALL | NULL | NULL | NULL | NULL | 100000 | |
- | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 10 | db.p.regno | 1 | |
- +----+-------------+-------+--------+---------------+---------+---------+------------+--------+-------+
- 2 rows in set (0.00 sec)
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