MySql開啓慢查詢日誌並使用pt-query-digest 分析

時間  2019-12-05
標籤 mysql 開啓 查詢 日誌 並使 query digest 分析 欄目 MySQL 简体版
原文   原文鏈接

慢查詢日誌會將查詢過程當中超出你設置的時間的查詢記錄下來，以便供開發者進行分析和優化。mysql

 

1. 開啓慢查詢

1.1 查看當前設置

mysql> show variables like "%query%";

輸出sql

+------------------------------+-----------------------------------------+
| Variable_name                | Value                                   |
+------------------------------+-----------------------------------------+
| binlog_rows_query_log_events | OFF                                     |
| ft_query_expansion_limit     | 20                                      |
| have_query_cache             | YES                                     |
| long_query_time              | 10.000000                               |
| query_alloc_block_size       | 8192                                    |
| query_cache_limit            | 1048576                                 |
| query_cache_min_res_unit     | 4096                                    |
| query_cache_size             | 16777216                                |
| query_cache_type             | OFF                                     |
| query_cache_wlock_invalidate | OFF                                     |
| query_prealloc_size          | 8192                                    |
| slow_query_log               | OFF                                     |
| slow_query_log_file          | /var/lib/mysql/lgj-Lenovo-G470-slow.log |
+------------------------------+-----------------------------------------+

三個參數ubuntu

  • slow_query_log   ON/OFF ,使能開關
  • slow_query_log_file   慢查詢日誌目錄和文件名稱
  • long_query_time    超過該時間則進行記錄，5.1以前只設置到秒，5.1開始支持毫秒。

注意，開啓慢查詢會影響性能，所以應當在某一段時間內開啓，記錄一段時間後關閉掉。curl

1.2 配置

lgj@lgj-Lenovo-G470:~/db-analysis$ whereis mysql
mysql: /usr/bin/mysql /usr/lib/mysql /etc/mysql /usr/local/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz

個人配置文件在/etc/mysql目錄下的my.cnfsocket

配置工具

[mysqld]
port=3307
skip-grant-tables
!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mysql.conf.d/

#打開慢查詢
slow_query_log = ON
#設置超時時間爲0，也就是記錄全部的查詢
long_query_time = 0

設置完後保存，從新啓動mysql性能

service mysql  restart

從新查看參數，已經更改。優化

mysql> show variables like "%query%";
+------------------------------+-----------------------------------------+
| Variable_name                | Value                                   |
+------------------------------+-----------------------------------------+
| binlog_rows_query_log_events | OFF                                     |
| ft_query_expansion_limit     | 20                                      |
| have_query_cache             | YES                                     |
| long_query_time              | 0.000000                                |
| query_alloc_block_size       | 8192                                    |
| query_cache_limit            | 1048576                                 |
| query_cache_min_res_unit     | 4096                                    |
| query_cache_size             | 16777216                                |
| query_cache_type             | OFF                                     |
| query_cache_wlock_invalidate | OFF                                     |
| query_prealloc_size          | 8192                                    |
| slow_query_log               | ON                                      |
| slow_query_log_file          | /var/lib/mysql/lgj-Lenovo-G470-slow.log |
+------------------------------+-----------------------------------------+

1.3 查詢

 隨便執行一條查詢語句，而後查看慢查詢日誌。url

/usr/sbin/mysqld, Version: 5.7.25-0ubuntu0.18.04.2 ((Ubuntu)). started with:
Tcp port: 3306  Unix socket: /var/run/mysqld/mysqld.sock
Time                 Id Command    Argument
/usr/sbin/mysqld, Version: 5.7.25-0ubuntu0.18.04.2-log ((Ubuntu)). started with:
Tcp port: 3306  Unix socket: /var/run/mysqld/mysqld.sock
Time                 Id Command    Argument
/usr/sbin/mysqld, Version: 5.7.25-0ubuntu0.18.04.2-log ((Ubuntu)). started with:
Tcp port: 3306  Unix socket: /var/run/mysqld/mysqld.sock
Time                 Id Command    Argument
;
# Time: 2019-02-27T14:07:42.841770Z
# User@Host: skip-grants user[lgj] @ localhost []  Id:     2
# Query_time: 0.016232  Lock_time: 0.000000 Rows_sent: 0  Rows_examined: 0
SET timestamp=1551276462;
;
# Time: 2019-02-27T14:07:51.774192Z
# User@Host: skip-grants user[lgj] @ localhost []  Id:     2
# Query_time: 0.000485  Lock_time: 0.000221 Rows_sent: 1  Rows_examined: 1
SET timestamp=1551276471;
select * from user;
# Time: 2019-02-27T14:07:55.839223Z
# User@Host: skip-grants user[lgj] @ localhost []  Id:     2
# Query_time: 0.000564  Lock_time: 0.000259 Rows_sent: 1  Rows_examined: 1
SET timestamp=1551276475;
# 查詢語句
select * from user;
# 記錄時間
# Time: 2019-02-27T14:08:07.404666Z
# User@Host: skip-grants user[lgj] @ localhost []  Id:     2
#查詢時間   鎖表時間  
# Query_time: 0.006318  Lock_time: 0.000435 Rows_sent: 13  Rows_examined: 1026
SET timestamp=1551276487;

從上面能夠獲知查詢時間和鎖表時間，可是若是文件比較大，查找時間最長的查詢將會很是麻煩，須要使用相關的工具來進行分析。spa

《高性能mysql》推薦使用 qt-query-digest 工具

2. qt-query-digest的使用

2.1 安裝

  •   建立目錄： mkdir db-analysis && cd db-analysis
  •  下載 pt-query-digest: curl -LO https://percona.com/get/pt-query-digest
  •   設置執行權限：chmod +x pt-query-digest
  •   將慢查詢日誌的文件複製到當前的目錄下
  •   執行分析：  ./pt-query-digest lgj-Lenovo-G470-slow.log

結果

# 220ms user time, 10ms system time, 33.67M rss, 90.27M vsz
# Current date: Wed Feb 27 22:55:05 2019
# Hostname: lgj-Lenovo-G470
# Files: lgj-Lenovo-G470-slow.log
# Overall: 9 total, 7 unique, 0.24 QPS, 0.00x concurrency ________________
# Time range: 2019-02-27T14:07:29 to 2019-02-27T14:08:07
# Attribute          total     min     max     avg     95%  stddev  median
# ============     ======= ======= ======= ======= ======= ======= =======
# Exec time          185ms   225us   122ms    21ms   122ms    37ms     6ms
# Lock time            2ms       0   485us   186us   467us   166us   159us
# Rows sent             50       0      13    5.56   12.54    5.25    0.99
# Rows examine       2.03k       0   1.00k  230.44 1012.63  419.72    0.99
# Query size           198      11      32      22   31.70    7.35   17.65

# Profile
# Rank Query ID                          Response time Calls R/Call V/M   
# ==== ================================= ============= ===== ====== ===== 
#    1 0x751417D45B8E80EE5CBA2034458B...  0.1223 66.1%     1 0.1223  0.00 SHOW DATABASES
#    2 0xA11944C87A6A5C16FB38455BF703...  0.0320 17.3%     1 0.0320  0.00 SELECT
#    3 0x898255B1BE4F8C3044AE35A18286...  0.0155  8.4%     1 0.0155  0.00 ADMIN INIT DB
#    4 0xE77769C62EF669AA7DD5F6760F2D...  0.0134  7.3%     2 0.0067  0.00 SHOW VARIABLES
# MISC 0xMISC                             0.0018  1.0%     4 0.0004   0.0 <3 ITEMS>

# Query 1: 0 QPS, 0x concurrency, ID 0x751417D45B8E80EE5CBA2034458B5BC9 at byte 1471
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.00
# Time range: all events occurred at 2019-02-27T14:07:42
# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count         11       1
# Exec time     66   122ms   122ms   122ms   122ms   122ms       0   122ms
# Lock time      6   110us   110us   110us   110us   110us       0   110us
# Rows sent     20      10      10      10      10      10       0      10
# Rows examine   0      10      10      10      10      10       0      10
# Query size     7      14      14      14      14      14       0      14
# String:
# Databases    microblog
# Hosts        localhost
# Users        skip-grants user
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms
#  10ms
# 100ms  ################################################################
#    1s
#  10s+
show databases\G

# Query 2: 0 QPS, 0x concurrency, ID 0xA11944C87A6A5C16FB38455BF7035609 at byte 1008
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.00
# Time range: all events occurred at 2019-02-27T14:07:42
# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count         11       1
# Exec time     17    32ms    32ms    32ms    32ms    32ms       0    32ms
# Lock time      0       0       0       0       0       0       0       0
# Rows sent      2       1       1       1       1       1       0       1
# Rows examine   0       0       0       0       0       0       0       0
# Query size     8      17      17      17      17      17       0      17
# String:
# Hosts        localhost
# Users        skip-grants user
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms
#  10ms  ################################################################
# 100ms
#    1s
#  10s+
# EXPLAIN /*!50100 PARTITIONS*/
SELECT DATABASE()\G

# Query 3: 0 QPS, 0x concurrency, ID 0x898255B1BE4F8C3044AE35A182869033 at byte 1225
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.00
# Time range: all events occurred at 2019-02-27T14:07:42
# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count         11       1
# Exec time      8    15ms    15ms    15ms    15ms    15ms       0    15ms
# Lock time      0       0       0       0       0       0       0       0
# Rows sent      0       0       0       0       0       0       0       0
# Rows examine   0       0       0       0       0       0       0       0
# Query size    15      30      30      30      30      30       0      30
# String:
# Databases    microblog
# Hosts        localhost
# Users        skip-grants user
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms
#  10ms  ################################################################
# 100ms
#    1s
#  10s+
administrator command: Init DB\G

# Query 4: 0.05 QPS, 0.00x concurrency, ID 0xE77769C62EF669AA7DD5F6760F2D2EBB at byte 775
# This item is included in the report because it matches --limit.
# Scores: V/M = 0.00
# Time range: 2019-02-27T14:07:30 to 2019-02-27T14:08:07
# Attribute    pct   total     min     max     avg     95%  stddev  median
# ============ === ======= ======= ======= ======= ======= ======= =======
# Count         22       2
# Exec time      7    13ms     6ms     7ms     7ms     7ms   559us     7ms
# Lock time     54   920us   435us   485us   460us   485us    35us   460us
# Rows sent     52      26      13      13      13      13       0      13
# Rows examine  98   2.00k   1.00k   1.00k   1.00k   1.00k       0   1.00k
# Query size    29      58      29      29      29      29       0      29
# String:
# Databases    microblog
# Hosts        localhost
# Users        skip-grants user
# Query_time distribution
#   1us
#  10us
# 100us
#   1ms  ################################################################
#  10ms
# 100ms
#    1s
#  10s+
show variables like "%query%"\G
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