首先,我需要一个分页功能,通过使用couplewhere条件限制以下查询查找中的结果。
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
配置文件
配置文件详细信息
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,我对上面的查询/设计没有问题,直到表增长到300k行,查询运行需要 OK, Time: 0.726000s
我认为结果太慢了。
我尝试使用count(*)根据上述条件对行进行计数,并得到一些大致相同的结果,我需要有更快的方法从查找条件中获取行数,以使分页系统以更少的等待时间按预期工作。
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,由于使用以下命令从作用域中产生较大的行,因此没有多大帮助:
AND a.country = 'INDONESIA'
AND a.gender = 0
结果(148801行范围限制,按国家/地区,性别等于0),如果我与城市配对,这不是问题,查询时间是相当长的,因为行的结果要小得多,但当某一天有较大的行时,仍然会是一个问题。
任何可能要求解释问题的人:
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explain result中看到的,没有表扫描或使用临时或使用范围,只有索引条件。我想,如果表中至少有100万行按国家范围返回,只要将时间与缩放行相乘30万就糟了:(。
下表定义有助于分析问题:
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`)
)
如何找到解决方案,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
我正在尝试你之前的建议,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);
我试图选择count(*)而不与profile\u detail连接:
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
结果计时在0.7秒到0.35秒之间不稳定,我不知道为什么会这样。下面以json格式解释查询计划,以帮助找出罪魁祸首。
{
"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"
]
}
}
]
}
}
1条答案
按热度按时间n9vozmp41#
并改变
birth_date
“可销售”:到
这样优化器就可以使用
birth_date
.LIMIT 33
--你在乎哪33排吗?也许你需要一个ORDER BY
?不要这样做
JOIN ( SELECT ... profile_details ... )
当一个计划JOIN profile_details ...
会有用的。SQL_CALC_FOUND_ROWS
代价不菲。把它取下来看看它走得有多快,然后决定是否值得保留。我不认为你需要
JOIN profile_details
不止一次,尤其是因为它与profiles
.我的意思是:
而不是
JOIN ( SELECT ... )
刚刚然后将这些添加到where子句中:
避免文件排序
建立索引时,请按以下顺序包括列
所有列测试为“列=常量”。
一个范围(例如
BETWEEN
). 如果这和ORDER BY
那么就可能避免使用“文件排序”。如果没有“范围”
WHERE
,那么所有列测试为“列=常量”。
这个
ORDER BY
列--假设它们都是DESC
或全部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“range”和不同的“order by”。考虑以下几点。你有一个姓和名的人的名单。查询结果是