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explain extended  SELECT check_fine from local_profiles WHERE (name = 'myprofile');

+----+-------------+-----------------+------+---------------+------+---------+------+------+----------+-------------+
| id | select_type | table           | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra       |
+----+-------------+-----------------+------+---------------+------+---------+------+------+----------+-------------+ 
|  1 | SIMPLE      | local_profiles  | ALL  | NULL          | NULL | NULL    | NULL |    1 |   100.00 | Using where |
+----+-------------+-----------------+------+---------------+------+---------+------+------+----------+-------------+

+--------------+--------------+------+-----+---------+----------------+
| Field        | Type         | Null | Key | Default | Extra          |
+--------------+--------------+------+-----+---------+----------------+
| id           | int(11)      | NO   | PRI | NULL    | auto_increment |
| name         | varchar(256) | NO   |     | NULL    |                |
| check_fine   | tinyint(4)   | NO   |     | 0       |                |
+--------------+--------------+------+-----+---------+----------------+

mysql 慢查询日志设置（log-queries-not-using-indexes = 0）

# Query 10: 0.03 QPS, 0.19x concurrency, ID xxxxxxxxxxxxxxxxx at byte 53863711
# This item is included in the report because it matches --outliers.
# Scores: V/M = 1.17


# Rank Query ID           Response time     Calls R/Call  V/M   Item
# ==== ================== ================= ===== ======= ===== ==========
#    5 xxxxxxxxxxxxxxxxx  16710.3680  1.8%  2203  7.5853  1.17 SELECT local_profiles


# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count          1    2468
# Exec time      1  18379s      5s     33s      7s     13s      3s      6s
# Lock time      0   471ms    64us    32ms   258us   259us   896us    90us
# Rows sent      0   1.16k       0       1    0.54    0.99    0.49    0.99
# Rows examine   0   1.16k       0       1    0.54    0.99    0.49    0.99
# Query size     0 121.71k      57      57      57      57       0      57
  1. 我有一个只有五行三列的表。然而，上面提到的简单查询显示在 mysql 慢查询日志中。

这个简单的查询将如何影响性能。

  1. 该项目包含在报告中是什么意思， 因为它与 --outliers 匹配

    在此处输入代码

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1 回答 1

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我可以回答这两个问题之一...

2. 什么意思 This item is included in the report because it matches --outliers

这看起来像pt-query-digest的输出，它有一个--outliers 选项。它用于控制哪些查询被报告为慢。它需要参数，所以为什么选择这个查询取决于传递给它的内容。

于 2016-03-17T17:34:37.380 回答