sql查询速度较慢

gab6jxml 于 2021-06-20 发布在 Mysql

关注(0)|答案(2)|浏览(389)

我有多个sql查询，它们在一台开发服务器上的运行速度比另一台慢得多（长2-4倍）。我使用的是digitalocean，两台服务器都是用同一个快照制作的，在硬件和数据方面都是相同的。dev1是我的主要开发服务器，我在上面优化代码，所以数据略有不同。我觉得我可能已经更改或修改了一个mysql设置，但没有在dev2上复制，但我找不到任何区别。在我能想到的所有配置文件上运行diff并没有产生任何线索。两台服务器都在运行
乌布努图14.04
64 gb内存
MySQL5.6版本
PHP5.5
我的后端使用php，当准备一个包含大量绑定值的语句时，pdo中有一个bug。为了解决这个问题，我创建了临时表，并将它们用作where语句的子查询。所有这些都在mysql cli中运行，以排除任何php问题。

CREATE TEMPORARY TABLE IF NOT EXISTS temp_a LIKE a;

INSERT INTO temp_a SELECT * FROM a WHERE id in (1,2,3,4,8,30,31,128,129,130,197,198,199,200,201,204,206,207,208,218,219,220,221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,271,273,284,641,4691,5313,6845,5,7,262,6,528,817,818,819,820,821,9,628,5178;

SELECT t1.pId, t1.*, t2.username, t2.email, t2.customer_id 
FROM b_actions t1 
JOIN users t2 
ON t1.user_id = t2.id 
WHERE t1.action_name NOT IN ('action1', 'action2', 'action3') AND t1.user_dismissed = 0 
AND t1.pId IN (SELECT id FROM temp_a) 
ORDER BY datetime DESC`);

表b\U动作模式

CREATE TABLE `b_actions` (
`id` int(11) unsigned NOT NULL AUTO_INCREMENT,
`datetime` datetime NOT NULL,
`user_id` int(11) DEFAULT NULL,
`pId` int(11) NOT NULL,
`action_name` varchar(255) CHARACTER SET latin1 DEFAULT NULL,
`data` mediumtext COLLATE utf8_unicode_ci,
`schedule_type` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`schedule_datetime` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`action_state` int(11) NOT NULL,
`user_dismissed` smallint(1) NOT NULL,
`message` varchar(500) COLLATE utf8_unicode_ci DEFAULT NULL,
`created_on` datetime DEFAULT CURRENT_TIMESTAMP,
`updated_on` datetime DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
PRIMARY KEY (`id`),
KEY `pId` (`pId`),
KEY `datetime` (`datetime`),
KEY `user_id` (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci

dev1:快速查询（5377行（0.79秒））-解释：


***************************1. row***************************

        id: 1
select_type: SIMPLE
        table: temp_a
        type: index
possible_keys: PRIMARY,id
        key: id
    key_len: 4
        ref: NULL
        rows: 5889
        Extra: Using index; Using temporary; Using filesort

***************************2. row***************************

        id: 1
select_type: SIMPLE
        table: t1
        type: ref
possible_keys: pId,user_id
        key: pId
    key_len: 4
        ref: db.temp_a.id
        rows: 15
        Extra: Using index condition; Using where

***************************3. row***************************

        id: 1
select_type: SIMPLE
        table: t2
        type: eq_ref
possible_keys: id
        key: id
    key_len: 4
        ref: db.t1.user_id
        rows: 1
        Extra: Using where

dev2:较慢的查询（集合中5386行（1.31秒））-解释


***************************1. row***************************

        id: 1
select_type: SIMPLE
        table: temp_a
        type: index
possible_keys: PRIMARY,id
        key: id
    key_len: 4
        ref: NULL
        rows: 8866
        Extra: Using index; Using temporary; Using filesort

***************************2. row***************************

        id: 1
select_type: SIMPLE
        table: t1
        type: ref
possible_keys: pId,user_id
        key: pId
    key_len: 4
        ref: db.temp_a.id
        rows: 23
        Extra: Using index condition; Using where

***************************3. row***************************

        id: 1
select_type: SIMPLE
        table: t2
        type: eq_ref
possible_keys: id
        key: id
    key_len: 4
        ref: db.t1.user_id
        rows: 1
        Extra: Using where

mysql/my.cnf都是相同的


# 

# The MySQL database server configuration file.

# 

# You can copy this to one of:

# - "/etc/mysql/my.cnf" to set global options,

# - "~/.my.cnf" to set user-specific options.

# 

# One can use all long options that the program supports.

# Run program with --help to get a list of available options and with

# --print-defaults to see which it would actually understand and use.

# 

# For explanations see

# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients

# It has been reported that passwords should be enclosed with ticks/quotes

# escpecially if they contain "#" chars...

# Remember to edit /etc/mysql/debian.cnf when changing the socket location.

[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs

# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.

[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]

# 

# * Basic Settings

# 

user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking

# 

# Instead of skip-networking the default is now to listen only on

# localhost which is more compatible and is not less secure.

bind-address        = 127.0.0.1

# 

# * Fine Tuning

# 

key_buffer      = 4G
max_allowed_packet  = 16M
thread_stack        = 192K
thread_cache_size       = 8

# This replaces the startup script and checks MyISAM tables if needed

# the first time they are touched

myisam-recover         = BACKUP
max_connections        = 2000

# table_cache            = 1024

# thread_concurrency     = 10

# 

# * Query Cache Configuration

# 

query_cache_limit   = 10M
query_cache_size        = 256M

# 

# * Logging and Replication

# 

# Both location gets rotated by the cronjob.

# Be aware that this log type is a performance killer.

# As of 5.1 you can enable the log at runtime!

# general_log_file        = /var/log/mysql/mysql.log

# general_log             = 1

# 

# Error log - should be very few entries.

# 

log_error = /var/log/mysql/error.log

# 

# Here you can see queries with especially long duration

# log_slow_queries   = /var/log/mysql/mysql-slow.log

# long_query_time = 2

# log-queries-not-using-indexes

# 

# The following can be used as easy to replay backup logs or for replication.

# note: if you are setting up a replication slave, see README.Debian about

# other settings you may need to change.

# server-id      = 1

# log_bin            = /var/log/mysql/mysql-bin.log

expire_logs_days    = 10
max_binlog_size         = 100M

# binlog_do_db       = include_database_name

# binlog_ignore_db   = include_database_name

# 

# * InnoDB

# 

# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.

# Read the manual for more InnoDB related options. There are many!

# 

# * Security Features

# 

# Read the manual, too, if you want chroot!

# chroot = /var/lib/mysql/

# 

# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".

# 

# ssl-ca=/etc/mysql/cacert.pem

# ssl-cert=/etc/mysql/server-cert.pem

# ssl-key=/etc/mysql/server-key.pem

slow-query-log = 1
slow-query-log-file = /var/log/mysql/localhost-slow.log
long_query_time = 1

# log-queries-not-using-indexes

[mysqldump]
quick
quote-names
max_allowed_packet  = 16M

[mysql]

# no-auto-rehash # faster start of mysql but no tab completition

[isamchk]
key_buffer      = 16M

# 

# * IMPORTANT: Additional settings that can override those from this file!

# The files must end with '.cnf', otherwise they'll be ignored.

# 

!includedir /etc/mysql/conf.d/

mysql mysql-5.6 query-optimization

来源：https://stackoverflow.com/questions/52224679/sql-query-slower-on-identical-server

2条答案

按热度按时间

wmomyfyw1#

可能不是您想要的，但这些建议有助于优化所有服务器上的查询：
一是增加相关指标：

ALTER TABLE `b_actions` ADD INDEX `b_actions_idx_dismiss_id_name_pid` (`user_dismissed`,`user_id`,`action_name`,`pId`);
ALTER TABLE `users` ADD INDEX `users_idx_id_usernam_email_id` (`id`,`username`,`email`,`customer_id`);
ALTER TABLE `temp_a` ADD INDEX `temp_a_idx_id` (`id`);

然后运行此查询转换，而不是原始查询。主要的变化是我已经将in子查询转换为exists子查询，因为它通常性能更好。

SELECT
        t1.pId,
        t1.*,
        t2.username,
        t2.email,
        t2.customer_id 
    FROM
        b_actions t1 
    JOIN
        users t2 
            ON t1.user_id = t2.id 
    WHERE
        t1.action_name NOT IN (
            'action1', 'action2', 'action3'
        ) 
        AND t1.user_dismissed = 0 
        AND EXISTS (
            SELECT
                1 
            FROM
                temp_a 
            WHERE
                t1.pId = temp_a.id
        ) 
    ORDER BY
        t1.datetime DESC

赞(0）回复(0）举报 2021-06-20

ao218c7q2#

我看不出有什么背景 innodb_buffer_pool_size . 这是innodb表最重要的设置。 50G 可能是个不错的环境。
使用 JOIN 而不是 AND t1.pId IN (SELECT id FROM temp_a) .
在那之后，加上