[英]how can i make the following query more efficient in lookup with many conditions
首先,我需要通過使用幾個 where 條件限制以下查詢查找中的結果來具有分頁功能。
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;
這里的所有表都是與表用戶的一對一關系,它們是
在用戶中使用 id 列作為主鍵,在其他表中使用 uid 作為外鍵。 一開始,我對上述查詢/設計沒有問題,直到表增長到 300K 行,查詢運行OK, Time: 0.726000s
來獲取結果,這對我來說太慢了。
我嘗試使用 count(*) 根據上述條件計算行數並獲得大致相同的結果,我需要有更快的方法從查找條件中獲取行數,以使分頁系統按預期工作等待的時間。
正如您在查詢中看到的,我正在使用:
FORCE INDEX(profiles_country_city_gender_index)
我認為通過使用 scope 產生的較大行並沒有太大幫助:
AND a.country = 'INDONESIA'
AND a.gender = 0
結果(148801 行 scope 限制按國家和性別等於 0),如果我與城市配對,則查詢時間不是問題,因為行結果要小得多,但當某天有更大的行時仍然會出現問題。
對於任何可能要求查詢解釋的人:
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 | |
正如您在解釋結果中看到的那樣,沒有表掃描或使用臨時或使用范圍,只有索引條件。 我想如果表格有至少 100 萬行由國家 scope 返回,只需將縮放行的時間乘以 300K 就很糟糕了:(。
下面是表定義,以防有助於分析問題:
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`)
)
我怎樣才能找到解決方案,我是否需要重新設計表格以獲得理想的系統? 也許這是最后的選擇。
編輯
我正在嘗試您之前的建議,首先我在三列中添加了一個索引:
CREATE INDEX profiles_country_gender_birth_date_index on `profiles`(country,gender,birth_date);
我試圖 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
結果時間在 0.7 秒到 0.35 秒之間不穩定,我不知道為什么會這樣。 以下是 Json 格式的解釋查詢計划,以防萬一幫助找出罪魁禍首。
{
"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
並將birth_date
的使用更改為“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
這樣優化器就可以使用birth_date
。
LIMIT 33
-- 你關心哪 33 行? 也許你需要一個ORDER BY
?
當計划JOIN profile_details...
可行時,不要執行JOIN ( SELECT... profile_details... )
。
SQL_CALC_FOUND_ROWS
需要花費一些東西。 將其移除以查看其運行速度,然后決定是否值得保留。
我認為您不需要多次JOIN profile_details
,特別是因為它與profiles
是 1:1 的。
這就是我的意思:
而不是JOIN ( SELECT... )
剛剛
JOIN profile_details AS d USING(uid)
然后將這些添加到 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!
構建索引時,按此順序包含列
BETWEEN
)。 如果這與ORDER BY
相同,則可能會避免使用“文件排序”。 如果WHERE
中沒有“范圍”,則
ORDER BY
列——假設它們都是DESC
或所有ASC
(或者,在 MySQL 8.0 中,匹配INDEX
定義)。 這可能會避免“文件排序”。但是索引不能同時處理“范圍”和不同的“排序依據”。 考慮以下。 您有一個包含姓氏和名字的人員列表。 查詢是
SELECT ...
WHERE last_name LIKE 'Ja%' -- a "range"
ORDER BY first_name;
INDEX(last_name, first_name)
將有助於WHERE
,但會使 first_names 混亂。 反之亦然。
(這是一種簡化,有關更多詳細信息,請參閱http://mysql.rjweb.org/doc.php/index_cookbook_mysql 。)
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