[英]how can i make the following query more efficient in lookup with many conditions
首先,我需要通过使用几个 where 条件限制以下查询查找中的结果来具有分页功能。
SELECT SQL_CALC_FOUND_ROWS
a.uid, b.NAME
FROM
`profiles` AS a FORCE INDEX(profiles_country_city_gender_index)
JOIN `users` AS b
ON b.id = a.uid
AND a.country = 'INDONESIA'
AND a.gender = 0
JOIN (
SELECT
a.uid
FROM
profile_details AS a
JOIN profile_details AS kids ON kids.uid = a.uid
AND kids.kids_pref = 1
JOIN profile_details AS current ON current.uid = a.uid
AND current.current_relationship = 1
JOIN profile_details AS smoking ON smoking.uid = a.uid
AND smoking.smoking_pref = 1
) AS e ON e.uid = a.uid
AND ( TIMESTAMPDIFF( YEAR, a.birth_date, NOW()) BETWEEN 25 AND 35 )
LIMIT 33;
这里的所有表都是与表用户的一对一关系,它们是
在用户中使用 id 列作为主键,在其他表中使用 uid 作为外键。 一开始,我对上述查询/设计没有问题,直到表增长到 300K 行,查询运行OK, Time: 0.726000s
来获取结果,这对我来说太慢了。
我尝试使用 count(*) 根据上述条件计算行数并获得大致相同的结果,我需要有更快的方法从查找条件中获取行数,以使分页系统按预期工作等待的时间。
正如您在查询中看到的,我正在使用:
FORCE INDEX(profiles_country_city_gender_index)
我认为通过使用 scope 产生的较大行并没有太大帮助:
AND a.country = 'INDONESIA'
AND a.gender = 0
结果(148801 行 scope 限制按国家和性别等于 0),如果我与城市配对,则查询时间不是问题,因为行结果要小得多,但当某天有更大的行时仍然会出现问题。
对于任何可能要求查询解释的人:
Explain SELECT SQL_CALC_FOUND_ROWS
a.uid,
b.NAME ...
Results:
| select_type | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+-------------+---------+--------+------------------------------------+------------------------------------+---------+------------------+--------+-----------+------------------------------------+
| SIMPLE | a | ref | profiles_country_city_gender_index | profiles_country_city_gender_index | 242 | const | 148801 | 10.00 | Using index condition; Using where |
| SIMPLE | a | ref | profile_details_uid_foreign | profile_details_uid_foreign | 3 | restfulapi.a.uid | 1 | 100.00.00 | Using index |
| SIMPLE | kids | ref | profile_details_uid_foreign | profile_details_uid_foreign | 3 | restfulapi.a.uid | 1 | 10.00 | Using where |
| SIMPLE | current | ref | profile_details_uid_foreign | profile_details_uid_foreign | 3 | restfulapi.a.uid | 1 | 10.00 | Using where |
| SIMPLE | smoking | ref | profile_details_uid_foreign | profile_details_uid_foreign | 3 | restfulapi.a.uid | 1 | 10.00 | Using where |
| SIMPLE | b | eq_ref | PRIMARY | PRIMARY | 3 | restfulapi.a.uid | 1 | 100.00.00 | |
正如您在解释结果中看到的那样,没有表扫描或使用临时或使用范围,只有索引条件。 我想如果表格有至少 100 万行由国家 scope 返回,只需将缩放行的时间乘以 300K 就很糟糕了:(。
下面是表定义,以防有助于分析问题:
CREATE TABLE `profile_details` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`uid` mediumint(8) unsigned NOT NULL,
`intents` tinyint(4) NOT NULL DEFAULT '3',
`height` smallint(6) DEFAULT NULL,
`body_type` tinyint(4) NOT NULL DEFAULT '5',
`kids_pref` tinyint(4) NOT NULL DEFAULT '1',
`drinking_pref` tinyint(4) NOT NULL DEFAULT '2',
`living_with` tinyint(4) NOT NULL DEFAULT '0',
`current_relationship` tinyint(4) NOT NULL DEFAULT '1',
`sexual_pref` tinyint(4) NOT NULL DEFAULT '1',
`smoking_pref` tinyint(4) NOT NULL DEFAULT '0',
`status_online` tinyint(4) NOT NULL DEFAULT '0',
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `profile_details_uid_foreign` (`uid`),
KEY `idx_multipart` (`intents`,`body_type`,`kids_pref`,`drinking_pref`,`living_with`,`current_relationship`,`sexual_pref`,`smoking_pref`),
CONSTRAINT `profile_details_uid_foreign` FOREIGN KEY (`uid`) REFERENCES `users` (`id`)
)
CREATE TABLE `profiles` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`uid` mediumint(8) unsigned NOT NULL,
`birth_date` date NOT NULL,
`gender` tinyint(4) NOT NULL DEFAULT '0',
`country` varchar(60) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'ID',
`city` varchar(60) COLLATE utf8mb4_unicode_ci DEFAULT 'Makassar',
`created_at` timestamp NULL DEFAULT NULL,
`updated_at` timestamp NULL DEFAULT NULL,
`latitude` double NOT NULL DEFAULT '0',
`longitude` double NOT NULL DEFAULT '0',
PRIMARY KEY (`id`),
KEY `profiles_uid_foreign` (`uid`),
KEY `profiles_birth_date_index` (`birth_date`),
KEY `profiles_latitude_longitude_index` (`latitude`,`longitude`),
KEY `profiles_country_city_gender_index` (`country`,`city`,`gender`),
KEY `idx_country_gender_birthdate` (`country`,`gender`,`birth_date`),
KEY `idx_country_city_gender_birthdate` (`country`,`city`,`gender`,`birth_date`),
CONSTRAINT `profiles_uid_foreign` FOREIGN KEY (`uid`) REFERENCES `users` (`id`)
)
我怎样才能找到解决方案,我是否需要重新设计表格以获得理想的系统? 也许这是最后的选择。
编辑
我正在尝试您之前的建议,首先我在三列中添加了一个索引:
CREATE INDEX profiles_country_gender_birth_date_index on `profiles`(country,gender,birth_date);
我试图 select Count(*) without JOIN with profile_detail:
SELECT
count(*)
FROM
`profiles` AS a
FORCE INDEX ( profiles_country_gender_birth_date_index )
JOIN `users` AS b ON b.id = a.uid
and
a.country = 'INDONESIA'
AND a.gender =1
AND a.birth_date BETWEEN NOW()- INTERVAL 35 YEAR
AND NOW()- INTERVAL 25 YEAR
结果时间在 0.7 秒到 0.35 秒之间不稳定,我不知道为什么会这样。 以下是 Json 格式的解释查询计划,以防万一帮助找出罪魁祸首。
{
"query_block": {
"select_id": 1,
"cost_info": {
"query_cost": "114747.38"
},
"nested_loop": [
{
"table": {
"table_name": "a",
"access_type": "range",
"possible_keys": [
"profiles_country_gender_birth_date_index"
],
"key": "profiles_country_gender_birth_date_index",
"used_key_parts": [
"country",
"gender",
"birth_date"
],
"key_length": "246",
"rows_examined_per_scan": 94066,
"rows_produced_per_join": 32961,
"filtered": "100.00",
"index_condition": "((`restfulapi`.`a`.`gender` = 1) and (`restfulapi`.`a`.`country` = 'INDONESIA') and (`restfulapi`.`a`.`birth_date` between <cache>((now() - interval 35 year)) and <cache>((now() - interval 25 year))))",
"cost_info": {
"read_cost": "15858.00",
"eval_cost": "6592.23",
"prefix_cost": "75194.00",
"data_read_per_join": "16M"
},
"used_columns": [
"uid",
"birth_date",
"gender",
"country"
]
}
},
{
"table": {
"table_name": "b",
"access_type": "eq_ref",
"possible_keys": [
"PRIMARY"
],
"key": "PRIMARY",
"used_key_parts": [
"id"
],
"key_length": "3",
"ref": [
"restfulapi.a.uid"
],
"rows_examined_per_scan": 1,
"rows_produced_per_join": 32961,
"filtered": "100.00",
"using_index": true,
"cost_info": {
"read_cost": "32961.15",
"eval_cost": "6592.23",
"prefix_cost": "114747.38",
"data_read_per_join": "89M"
},
"used_columns": [
"id"
]
}
}
]
}
}
INDEX(country, gender, birth_date) -- in this order
并将birth_date
的使用更改为“sargeable”:
AND ( TIMESTAMPDIFF( YEAR, a.birth_date, NOW()) BETWEEN 25 AND 35 )
至
AND a.birth_date BETWEEN NOW() - INTERVAL 35 YEAR
AND NOW() - INTERVAL 25 YEAR
这样优化器就可以使用birth_date
。
LIMIT 33
-- 你关心哪 33 行? 也许你需要一个ORDER BY
?
当计划JOIN profile_details...
可行时,不要执行JOIN ( SELECT... profile_details... )
。
SQL_CALC_FOUND_ROWS
需要花费一些东西。 将其移除以查看其运行速度,然后决定是否值得保留。
我认为您不需要多次JOIN profile_details
,特别是因为它与profiles
是 1:1 的。
这就是我的意思:
而不是JOIN ( SELECT... )
刚刚
JOIN profile_details AS d USING(uid)
然后将这些添加到 WHERE 子句中:
AND d.kids_pref = 1
AND d.current_relationship = 1
AND d.smoking_pref = 1
避免文件排序
INDEX(country, gender, -- Tested with '='
birth_date, -- Tested as a "range"
uid) -- For the ORDER BY -- Useless!
构建索引时,按此顺序包含列
BETWEEN
)。 如果这与ORDER BY
相同,则可能会避免使用“文件排序”。 如果WHERE
中没有“范围”,则
ORDER BY
列——假设它们都是DESC
或所有ASC
(或者,在 MySQL 8.0 中,匹配INDEX
定义)。 这可能会避免“文件排序”。但是索引不能同时处理“范围”和不同的“排序依据”。 考虑以下。 您有一个包含姓氏和名字的人员列表。 查询是
SELECT ...
WHERE last_name LIKE 'Ja%' -- a "range"
ORDER BY first_name;
INDEX(last_name, first_name)
将有助于WHERE
,但会使 first_names 混乱。 反之亦然。
(这是一种简化,有关更多详细信息,请参阅http://mysql.rjweb.org/doc.php/index_cookbook_mysql 。)
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