mysql - UNION 上的 SQL_CALC_FOUND_ROWS 以获取总行，但子查询上有 LIMIT

Question

我正在使用 MySQL 并有两个单独的表，PRE_REGISTERED 和 REGISTERED，我想使用 UNION 查询它们以获得整个组合结果。我也使用限制进行分页。最后，我想使用 SQL_CALC_FOUND_ROWS 获取总行进行分页。但是，我的数据在 PRE_REGISTERED 上非常大，大约有 160,000 行。如果我 UNION ALL 即使我将数据限制为每页 10 行，查询仍然需要很长时间（大约 6 秒）。像这样的查询

SELECT SQL_CALC_FOUND_ROWS U.* (
SELECT R.id, R.first_name, R.last_name, R.status
FROM REGISTERED R
WHERE R.status = 2)
UNION ALL
(SELECT PR.id, PR.first_name, PR.last_name, PR.status
FROM PRE_REGISTERED PR
WHERE PR.status = 3)
as U ORDER BY id LIMIT 0, 10

然后我尝试将 LIMIT 放在每个子查询上，结果令人着迷（大约 0.5 秒），但分页变得一团糟。

查询是这样的：

SELECT (
SELECT R.id, R.first_name, R.last_name, R.status
FROM REGISTERED R
WHERE R.status = 2 LIMIT 0, 10)
UNION ALL
(SELECT PR.id, PR.first_name, PR.last_name, PR.status
FROM PRE_REGISTERED PR
WHERE PR.status = 3 LIMIT 0, 10)
as U ORDER BY id LIMIT 0, 10

有没有办法在子查询中使用 LIMIT 来获得总行？

我决定提出整个查询，但它很长。我希望有人能发现错误并帮助我。我完全被困住了。

我的实际 SQL 查询

SELECT SQL_CALC_FOUND_ROWS U.*, S.name as spc_name, S.short_desc as 
spc_short_desc, GROUP_CONCAT(DISTINCT(S2.designation) SEPARATOR ', ') as 
spc_dsg, GROUP_CONCAT(DISTINCT(EM.designation) SEPARATOR ', ') as em_dsg, 
GROUP_CONCAT(DISTINCT(EF.designation) SEPARATOR ', ') as ef_dsg FROM (

(
 /** REGISTERED **/
SELECT D.id, D.doc_title, D.user_email, D.first_name, D.last_name, 
D.gender, D.dob, D.rating, D.no_of_rating, D.photo_file, 
D.verification_status, ((D.rating * 8) + D.no_of_rating) as rating_score, 
GROUP_CONCAT(DISTINCT(PP.id) SEPARATOR '|') as pp_id, 
GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.name)) SEPARATOR '|') as 
pp_name, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.address)) SEPARATOR 
'|') as pp_address, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.phone)) 
SEPARATOR '|') as pp_phone, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, 
V.name)) SEPARATOR '|') as pp_vil, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', 
PP.id, SD.name)) SEPARATOR '|') as pp_sub_d, 
GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, C.name)) SEPARATOR '|') as 
pp_city, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, P.name)) SEPARATOR '|') 
as pp_province, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.zipcode)) 
SEPARATOR '|') as pp_zip, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, 
RDPP.is_primary)) SEPARATOR '|') as pp_is_primary, 
GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.latitude)) SEPARATOR '|') as 
pp_lat, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.longitude)) SEPARATOR 
'|') as pp_lng, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, PP.type)) 
SEPARATOR '|') as pp_type, GROUP_CONCAT(DISTINCT(CONCAT_WS('#', PP.id, ( 
6371 * acos( cos( radians(-6.2087634) ) * cos( radians( PP.latitude ) ) * 
cos( radians( PP.longitude ) - radians(106.845599) ) + sin( 
radians(-6.2087634) ) * sin( radians( PP.latitude ) ) ) ))) SEPARATOR '|') 
as pp_distance, MIN(( 6371 * acos( cos( radians(-6.2087634) ) * cos( 
radians( PP.latitude ) ) * cos( radians( PP.longitude ) - 
radians(106.845599) ) + sin( radians(-6.2087634) ) * sin( radians( 
PP.latitude ) ) ) )) as min_pp_distance, 
GROUP_CONCAT(DISTINCT(CONCAT_WS('#', D.id, DPW.day, DPW.start_time)) 
SEPARATOR '|') as dpweek_stime , (SELECT comment FROM ref_doctor_review RDR 
WHERE RDR.doctor_id = D.id ORDER BY RDR.date DESC LIMIT 1) as comment, 1 as 
reg_status FROM doctor D LEFT JOIN ref_doctor_practice_place RDPP ON 
RDPP.doctor_id = D.id LEFT JOIN practice_place PP ON RDPP.practice_place_id 
= PP.id LEFT JOIN duty_period DPW ON RDPP.id = DPW.ref_doctor_pplace_id 
INNER JOIN village V ON PP.village_id = V.id INNER JOIN sub_district SD ON 
V.sub_district_id = SD.id INNER JOIN city C ON SD.city_id = C.id INNER JOIN 
province P ON P.id = C.province_id LEFT JOIN city DC ON D.city_id = DC.id 
INNER JOIN province DP ON DP.id = DC.province_id AND ( DP.name LIKE 'DKI 
Jakarta%' OR DP.long_name LIKE 'DKI Jakarta%' ) WHERE D.active_form >= 5 AND 
D.verification_status = 1 GROUP BY D.id )

联合所有（

/** PRE REGISTERED **/
SELECT RD.id * -1 as id, RD.doc_title as doc_title, NULL as user_email, 
RD.first_name, RD.last_name, RD.gender, 0 as dob, 0 as rating, 0 as 
no_of_rating, null as photo_file, null as verification_status, 0 as 
rating_score, PP.id as pp_id, CONCAT_WS('#', PP.id, PP.name) as pp_name, 
CONCAT_WS('#', PP.id, PP.address) as pp_address, CONCAT_WS('#', PP.id, 
PP.phone) as pp_phone, CONCAT_WS('#', PP.id, V.name)as pp_vil, 
CONCAT_WS('#', PP.id, SD.name) as pp_sub_d, CONCAT_WS('#', PP.id, C.name) as 
pp_city, CONCAT_WS('#', PP.id, P.name) as pp_province, CONCAT_WS('#', PP.id, 
PP.zipcode) as pp_zip, 1 pp_is_primary, CONCAT_WS('#', PP.id, PP.latitude) 
as pp_lat, CONCAT_WS('#', PP.id, PP.longitude) as pp_lng, CONCAT_WS('#', 
PP.id, PP.type) as pp_type, CONCAT_WS('#', PP.id, IF(PP.latitude <> 0 AND 
PP.longitude <> 0, ( 6371 * acos( cos( radians(-6.2087634) ) * cos( radians( 
PP.latitude ) ) * cos( radians( PP.longitude ) - radians(106.845599) ) + 
sin( radians(-6.2087634) ) * sin( radians( PP.latitude ) ) ) ), 0)) as 
pp_distance, IF(PP.latitude <> 0 AND PP.longitude <> 0, ( 6371 * acos( cos( 
radians(-6.2087634) ) * cos( radians( PP.latitude ) ) * cos( radians( 
PP.longitude ) - radians(106.845599) ) + sin( radians(-6.2087634) ) * sin( 
radians( PP.latitude ) ) ) ) , 9999999) as min_pp_distance, null as dp_week, 
null as comment, RD.status as reg_status FROM register_doctor RD LEFT JOIN 
ref_doctor_practice_place RDPP ON RDPP.doctor_id = RD.id * -1 LEFT JOIN 
practice_place PP ON PP.id = RDPP.practice_place_id LEFT JOIN village V ON 
V.id = PP.village_id LEFT JOIN sub_district SD ON SD.id = PP.sub_district_id 
LEFT JOIN city C ON C.id = SD.city_id INNER JOIN province P ON P.id = 
PP.province_id LEFT JOIN city RDC ON RDC.id = RD.city_id INNER JOIN province 
RDP ON RDP.id = RD.province_id AND ( RDP.name LIKE 'DKI Jakarta%' OR 
RDP.long_name LIKE 'DKI Jakarta%' ) WHERE RD.status = 2 GROUP BY RD.id )

) AS U INNER JOIN ref_doctor_specialty RDS ON RDS.doctor_id = U.id AND 
RDS.is_primary = 1 INNER JOIN specialty S ON S.id = RDS.specialty_id INNER 
JOIN ref_doctor_specialty RDS2 ON RDS2.doctor_id = U.id INNER JOIN specialty 
S2 ON S2.id = RDS2.specialty_id LEFT JOIN ref_doctor_education RDE ON 
RDE.doctor_id = U.id LEFT JOIN edu_magister EM ON RDE.type = 4 AND EM.id = 
RDE.ref_edu_id LEFT JOIN edu_fellowship EF ON RDE.type = 5 AND EF.id = 
RDE.ref_edu_id WHERE U.min_pp_distance < 100 OR U.min_pp_distance = 9999999 
GROUP BY U.id ORDER BY U.reg_status ASC, U.min_pp_distance ASC, RAND() LIMIT 
0,10

PS。我已经为索引放置了几乎所有必要的列。

我将在这里展示我的架构

CREATE TABLE `doctor` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `doc_title` varchar(15) DEFAULT NULL,
 `user_email` varchar(50) NOT NULL,
 `first_name` varchar(35) NOT NULL,
 `last_name` varchar(35) DEFAULT NULL,
 `gender` int(11) NOT NULL DEFAULT '0',
 `dob` bigint(11) NOT NULL DEFAULT '0',
 `rating` float NOT NULL DEFAULT '0',
 `no_of_rating` int(11) NOT NULL DEFAULT '0',
 `statement` text,
 `password` char(64) NOT NULL,
 `city_id` int(11) NOT NULL,
 `active_form` int(11) NOT NULL DEFAULT '0',
 `photo_file` varchar(40) NOT NULL,
 `str_number` char(6) DEFAULT NULL,
 `verify_file` varchar(40) DEFAULT NULL,
 `verification_status` int(11) NOT NULL COMMENT '0 = Not verified, 1 = Verified, 2 = Pending Verification',
 `reg_id` int(11) NOT NULL,
 `reg_timestamp` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
 PRIMARY KEY (`id`),
 KEY `city_id` (`city_id`),
 KEY `verification_status` (`verification_status`),
 KEY `active_form` (`active_form`),
 CONSTRAINT `doctor_ibfk_1` FOREIGN KEY (`city_id`) REFERENCES `city` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=261 DEFAULT CHARSET=latin1

CREATE TABLE `register_doctor` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `doc_title` int(11) NOT NULL,
 `first_name` varchar(35) NOT NULL,
 `last_name` varchar(35) DEFAULT NULL,
 `gender` int(11) NOT NULL,
 `city_id` int(11) NOT NULL,
 `province_id` int(11) NOT NULL,
 `status` int(11) NOT NULL COMMENT '0 = Pending; 1 = Verified, 2 = Not Reg Yet, 3 = Pending Approval',
 `str_number` char(6) DEFAULT NULL,
 `editted_by` int(11) DEFAULT NULL,
 `editted_date` bigint(20) DEFAULT NULL,
 PRIMARY KEY (`id`),
 KEY `city_id` (`city_id`),
 KEY `province_id` (`province_id`),
 KEY `status` (`status`),
 CONSTRAINT `register_doctor_ibfk_1` FOREIGN KEY (`city_id`) REFERENCES `city` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=179327 DEFAULT CHARSET=latin1

CREATE TABLE `practice_place` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(75) NOT NULL,
 `statement` text,
 `address` varchar(200) NOT NULL,
 `phone` varchar(15) NOT NULL,
 `fax` varchar(15) NOT NULL,
 `email` varchar(50) NOT NULL,
 `village_id` varchar(50) NOT NULL,
 `sub_district_id` varchar(50) NOT NULL,
 `province_id` varchar(50) NOT NULL,
 `zipcode` varchar(10) NOT NULL,
 `website` varchar(50) NOT NULL,
 `latitude` double NOT NULL,
 `longitude` double NOT NULL,
 `type` int(11) NOT NULL,
 `managed_by` int(11) DEFAULT '0',
 `doctor_group_id` int(11) NOT NULL,
 `category` varchar(50) NOT NULL,
 `photo_file` char(36) NOT NULL,
 `is_branch` int(11) NOT NULL,
 `parent_id` int(11) NOT NULL,
 `editted_by` int(11) NOT NULL,
 `editted_date` bigint(20) NOT NULL,
 `status` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `village_id` (`village_id`),
 KEY `doctor_group_id` (`doctor_group_id`),
 KEY `province_id` (`province_id`),
 KEY `type` (`type`),
 KEY `parent_id` (`parent_id`),
 KEY `longitude` (`longitude`),
 KEY `latitude` (`latitude`)
) ENGINE=InnoDB AUTO_INCREMENT=25554 DEFAULT CHARSET=latin1

CREATE TABLE `ref_doctor_practice_place` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `doctor_id` int(11) NOT NULL,
 `practice_place_id` int(11) NOT NULL,
 `is_primary` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 UNIQUE KEY `doctor_id_2` (`doctor_id`,`practice_place_id`),
 KEY `doctor_id` (`doctor_id`),
 KEY `practice_place_id` (`practice_place_id`),
 CONSTRAINT `ref_doctor_practice_place_ibfk_1` FOREIGN KEY (`practice_place_id`) REFERENCES `practice_place` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=38772 DEFAULT CHARSET=latin1

CREATE TABLE `ref_doctor_specialty` (
 `doctor_id` int(11) NOT NULL,
 `specialty_id` int(11) NOT NULL,
 `is_primary` int(11) NOT NULL DEFAULT '0',
 PRIMARY KEY (`doctor_id`,`specialty_id`),
 UNIQUE KEY `doctor_id_2` (`doctor_id`,`specialty_id`),
 KEY `doctor_id` (`doctor_id`),
 KEY `specialty_id` (`specialty_id`),
 KEY `is_primary` (`is_primary`),
 CONSTRAINT `ref_doctor_specialty_ibfk_1` FOREIGN KEY (`specialty_id`) REFERENCES `specialty` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE `ref_doctor_education` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `doctor_id` int(11) NOT NULL,
 `type` int(11) NOT NULL,
 `institution` varchar(150) NOT NULL,
 `ref_edu_id` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `doctor_id` (`doctor_id`),
 KEY `ref_edu_id` (`ref_edu_id`),
 KEY `type` (`type`)
) ENGINE=InnoDB AUTO_INCREMENT=187556 DEFAULT CHARSET=latin1

CREATE TABLE `edu_fellowship` (
 `id` int(11) NOT NULL,
 `name` varchar(150) NOT NULL,
 `designation` varchar(10) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE `edu_magister` (
 `id` int(11) NOT NULL,
 `name` varchar(55) NOT NULL,
 `designation` varchar(15) NOT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE `village` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(35) NOT NULL,
 `sub_district_id` int(11) NOT NULL,
 `zipcode` char(5) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `sub_district_id` (`sub_district_id`),
 CONSTRAINT `village_ibfk_1` FOREIGN KEY (`sub_district_id`) REFERENCES `sub_district` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=81360 DEFAULT CHARSET=latin1

CREATE TABLE `sub_district` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(35) NOT NULL,
 `city_id` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `city_id` (`city_id`),
 CONSTRAINT `sub_district_ibfk_1` FOREIGN KEY (`city_id`) REFERENCES `city` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7000 DEFAULT CHARSET=latin1

CREATE TABLE `province` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(40) NOT NULL,
 `long_name` varchar(40) NOT NULL,
 `abbreviation` char(2) NOT NULL,
 `area_group` varchar(20) DEFAULT NULL,
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=latin1

CREATE TABLE `duty_period` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `day` int(11) NOT NULL,
 `start_time` bigint(11) NOT NULL,
 `end_time` bigint(11) NOT NULL,
 `ref_doctor_pplace_id` int(11) NOT NULL DEFAULT '0',
 PRIMARY KEY (`id`),
 UNIQUE KEY `day` (`day`,`start_time`,`ref_doctor_pplace_id`),
 KEY `ref_doctor_pplace_id` (`ref_doctor_pplace_id`),
 CONSTRAINT `duty_period_ibfk_1` FOREIGN KEY (`ref_doctor_pplace_id`) REFERENCES `ref_doctor_practice_place` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=766 DEFAULT CHARSET=latin1

    CREATE TABLE `ref_doctor_review` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `date` bigint(20) NOT NULL,
 `doctor_id` int(11) NOT NULL,
 `helpfulness_rating` double NOT NULL,
 `punctuality_rating` double NOT NULL,
 `knowledge_rating` double NOT NULL,
 `staff_rating` double NOT NULL,
 `user_id` int(11) NOT NULL,
 `comment` text,
 `patient_id` int(11) NOT NULL DEFAULT '0',
 `is_anonymous` int(11) NOT NULL DEFAULT '0',
 `date_visit` bigint(20) DEFAULT NULL,
 PRIMARY KEY (`id`),
 KEY `doctor_id` (`doctor_id`),
 KEY `patient_id` (`user_id`),
 CONSTRAINT `ref_doctor_review_ibfk_1` FOREIGN KEY (`doctor_id`) REFERENCES `doctor` (`id`),
 CONSTRAINT `ref_doctor_review_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=latin1

CREATE TABLE `city` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(40) NOT NULL,
 `city_type` int(11) NOT NULL,
 `province_id` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `state_id` (`province_id`),
 CONSTRAINT `city_ibfk_1` FOREIGN KEY (`province_id`) REFERENCES `province` (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=515 DEFAULT CHARSET=latin1

CREATE TABLE `specialty` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(80) NOT NULL,
 `short_desc` varchar(50) NOT NULL,
 `name_en` varchar(80) NOT NULL,
 `short_desc_en` varchar(50) NOT NULL,
 `designation` varchar(15) NOT NULL,
 `is_popular` int(11) NOT NULL DEFAULT '0',
 `spc_group` int(11) NOT NULL,
 PRIMARY KEY (`id`),
 KEY `spc_group` (`spc_group`)
) ENGINE=InnoDB AUTO_INCREMENT=307 DEFAULT CHARSET=latin1

就这样！架构......唷。帮我看看德鲁。:)

解释表

| id | select_type | table | type   | possible_keys | key | key_len | ref | rows  | Extra |
    1   PRIMARY RDS ALL PRIMARY,doctor_id_2,doctor_id,specialty_id              30  Using where; Using temporary; Using filesort
    1   PRIMARY S   eq_ref  PRIMARY PRIMARY 4   lokadok.RDS.specialty_id    1   
    1   PRIMARY <derived2>  ref <auto_key0> <auto_key0> 8   lokadok.RDS.doctor_id   76  Using index condition
    1   PRIMARY RDS2    ref PRIMARY,doctor_id_2,doctor_id,specialty_id  PRIMARY 4   U.id    1   Using where; Using index
    1   PRIMARY S2  eq_ref  PRIMARY PRIMARY 4   lokadok.RDS2.specialty_id   1   
    1   PRIMARY RDE ref doctor_id   doctor_id   4   U.id    1   Using where
    1   PRIMARY EM  eq_ref  PRIMARY PRIMARY 4   lokadok.RDE.ref_edu_id  1   Using where
    1   PRIMARY EF  eq_ref  PRIMARY PRIMARY 4   lokadok.RDE.ref_edu_id  1   Using where
    2   DERIVED D   index   PRIMARY,city_id,full_name   PRIMARY 4       37  Using where
    2   DERIVED DC  eq_ref  PRIMARY,state_id    PRIMARY 4   lokadok.D.city_id   1   Using where
    2   DERIVED DP  eq_ref  PRIMARY PRIMARY 4   lokadok.DC.province_id  1   Using where
    2   DERIVED RDPP    ref practice_place_id,doctor_id doctor_id   4   lokadok.D.id    1   
    2   DERIVED DPW ref ref_doctor_pplace_id    ref_doctor_pplace_id    4   lokadok.RDPP.id 1   
    2   DERIVED PP  eq_ref  PRIMARY,village_id  PRIMARY 4   lokadok.RDPP.practice_place_id  1   Using where
    2   DERIVED V   eq_ref  PRIMARY,sub_district_id PRIMARY 4   lokadok.PP.village_id   1   Using where
    2   DERIVED SD  eq_ref  PRIMARY,city_id PRIMARY 4   lokadok.V.sub_district_id   1   
    2   DERIVED C   eq_ref  PRIMARY,state_id    PRIMARY 4   lokadok.SD.city_id  1   
    2   DERIVED P   eq_ref  PRIMARY PRIMARY 4   lokadok.C.province_id   1   
    3   DEPENDENT SUBQUERY  RDR ref doctor_id   doctor_id   4   func    1   Using where; Using filesort
    4   UNION   RDP ALL PRIMARY             36  Using where; Using temporary; Using filesort
    4   UNION   RD  ref PRIMARY,city_id,province_id,full_name   province_id 4   lokadok.RDP.id  210 Using where
    4   UNION   RDC eq_ref  PRIMARY PRIMARY 4   lokadok.RD.city_id  1   Using index
    4   UNION   RDPP    ref practice_place_id,doctor_id doctor_id   4   func    1   Using index condition
    4   UNION   PP  eq_ref  PRIMARY PRIMARY 4   lokadok.RDPP.practice_place_id  1   Using where
    4   UNION   P   eq_ref  PRIMARY PRIMARY 4   lokadok.PP.province_id  1   Using where
    4   UNION   V   eq_ref  PRIMARY PRIMARY 4   lokadok.PP.village_id   1   Using where
    4   UNION   SD  eq_ref  PRIMARY PRIMARY 4   lokadok.PP.sub_district_id  1   Using where
    4   UNION   C   eq_ref  PRIMARY PRIMARY 4   lokadok.SD.city_id  1   
        UNION RESULT    <union2,4>  ALL                     Using temporary

统计结果：

    +------------+----------------------------+------------+-----------------------+--------------+-----------------------+------------+-------------+-------------+-------------+----------+------------+
    | table_rows | table_name                 | non_unique | index_name            | seq_in_index | column_name           | collation  | cardinality | sub_part    | packed      | nullable | index_type |
    +------------+----------------------------+------------+-----------------------+--------------+-----------------------+------------+-------------+-------------+-------------+----------+------------+
    "514"        | "city"                     | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "514"       | NULL        | NULL        |          | "BTREE"
    "514"        | "city"                     | "1"        | "state_id"            | "1"          | "province_id"         | "A"        | "73"        | NULL        | NULL        |          | "BTREE"
    "259"        | "doctor"                   | "1"        | "active_form"         | "1"          | "active_form"         | "A"        | "12"        | NULL        | NULL        |          | "BTREE"
    "259"        | "doctor"                   | "1"        | "city_id"             | "1"          | "city_id"             | "A"        | "259"       | NULL        | NULL        |          | "BTREE"
    "259"        | "doctor"                   | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "259"       | NULL        | NULL        |          | "BTREE"
    "259"        | "doctor"                   | "1"        | "verification_status" | "1"          | "verification_status" | "A"        | "6"         | NULL        | NULL        |          | "BTREE"
    "690"        | "duty_period"              | "0"        | "day"                 | "2"          | "start_time"          | "A"        | "345"       | NULL        | NULL        |          | "BTREE"
    "690"        | "duty_period"              | "0"        | "day"                 | "1"          | "day"                 | "A"        | "14"        | NULL        | NULL        |          | "BTREE"
    "690"        | "duty_period"              | "0"        | "day"                 | "3"          | "ref_doctor_pplace_id"| "A"        | "690"       | NULL        | NULL        |          | "BTREE"
    "690"        | "duty_period"              | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "690"       | NULL        | NULL        |          | "BTREE"
    "690"        | "duty_period"              | "1"        | "ref_doctor_pplace_id"| "1"          | "ref_doctor_pplace_id"| "A"        | "345"       | NULL        | NULL        |          | "BTREE"
    "15"         | "edu_fellowship"           | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "15"        | NULL        | NULL        |          | "BTREE"
    "19"         | "edu_magister"             | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "19"        | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "doctor_group_id"     | "1"          | "doctor_group_id"     | "A"        | "411"       | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "latitude"            | "1"          | "latitude"            | "A"        | "5766"      | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "longitude"           | "1"          | "longitude"           | "A"        | "5766"      | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "parent_id"           | "1"          | "parent_id"           | "A"        | "5766"      | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "5766"      | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "province_id"         | "1"          | "province_id"         | "A"        | "74"        | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "type"                | "1"          | "type"                | "A"        | "4"         | NULL        | NULL        |          | "BTREE"
    "5766"       | "practice_place"           | "1"        | "village_id"          | "1"          | "village_id"          | "A"        | "5766"      | NULL        | NULL        |          | "BTREE"
    "36"         | "province"                 | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "36"        | NULL        | NULL        |          | "BTREE"
    "160406"     | "ref_doctor_education"     | "1"        | "doctor_id"           | "1"          | "doctor_id"           | "A"        | "160406"    | NULL        | NULL        |          | "BTREE"
    "160406"     | "ref_doctor_education"     | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "160406"    | NULL        | NULL        |          | "BTREE"
    "160406"     | "ref_doctor_education"     | "1"        | "ref_edu_id"          | "1"          | "ref_edu_id"          | "A"        | "128"       | NULL        | NULL        |          | "BTREE"
    "160406"     | "ref_doctor_education"     | "1"        | "type"                | "1"          | "type"                | "A"        | "8"         | NULL        | NULL        |          | "BTREE"
    "15871"      | "ref_doctor_practice_place"| "1"        | "doctor_id"           | "1"          | "doctor_id"           | "A"        | "15871"     | NULL        | NULL        |          | "BTREE"
    "15871"      | "ref_doctor_practice_place"| "0"        | "doctor_id_2"         | "2"          | "practice_place_id"   | "A"        | "15871"     | NULL        | NULL        |          | "BTREE"
    "15871"      | "ref_doctor_practice_place"| "0"        | "doctor_id_2"         | "1"          | "doctor_id"           | "A"        | "15871"     | NULL        | NULL        |          | "BTREE"
    "15871"      | "ref_doctor_practice_place"| "1"        | "practice_place_id"   | "1"          | "practice_place_id"   | "A"        | "3174"      | NULL        | NULL        |          | "BTREE"
    "15871"      | "ref_doctor_practice_place"| "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "15871"     | NULL        | NULL        |          | "BTREE"
    "2"          | "ref_doctor_review"        | "1"        | "doctor_id"           | "1"          | "doctor_id"           | "A"        | "2"         | NULL        | NULL        |          | "BTREE"
"2"          | "ref_doctor_review"        | "1"        | "patient_id"          | "1"          | "user_id"             | "A"        | "2"         | NULL        | NULL        |         | "BTREE"
"2"          | "ref_doctor_review"        | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "2"         | NULL        | NULL        |         | "BTREE"
"166830"     | "ref_doctor_specialty"     | "1"        | "is_primary"          | "1"          | "is_primary"          | "A"        | "2"         | NULL        | NULL        |         | "BTREE"
"166830"     | "ref_doctor_specialty"     | "0"        | "PRIMARY"             | "2"          | "specialty_id"        | "A"        | "166830"    | NULL        | NULL        |         | "BTREE"
"166830"     | "ref_doctor_specialty"     | "0"        | "PRIMARY"             | "1"          | "doctor_id"           | "A"        | "166830"    | NULL        | NULL        |         | "BTREE"
"166830"     | "ref_doctor_specialty"     | "1"        | "specialty_id"        | "1"          | "specialty_id"        | "A"        | "166"       | NULL        | NULL        |         | "BTREE"
"165958"     | "register_doctor"          | "1"        | "city_id"             | "1"          | "city_id"             | "A"        | "1152"      | NULL        | NULL        |         | "BTREE"
"165958"     | "register_doctor"          | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "165958"    | NULL        | NULL        |         | "BTREE"
"165958"     | "register_doctor"          | "1"        | "province_id"         | "1"          | "province_id"         | "A"        | "66"        | NULL        | NULL        |         | "BTREE"
"165958"     | "register_doctor"          | "1"        | "status"              | "1"          | "status"              | "A"        | "4"         | NULL        | NULL        |         | "BTREE"
"101"        | "specialty"                | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "101"       | NULL        | NULL        |         | "BTREE"
"101"        | "specialty"                | "1"        | "spc_group"           | "1"          | "spc_group"           | "A"        | "16"        | NULL        | NULL        |         | "BTREE"
"6999"       | "sub_district"             | "1"        | "city_id"             | "1"          | "city_id"             | "A"        | "1166"      | NULL        | NULL        |         | "BTREE"
"6999"       | "sub_district"             | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "6999"      | NULL        | NULL        |         | "BTREE"
"80700"      | "village"                  | "0"        | "PRIMARY"             | "1"          | "id"                  | "A"        | "80700"     | NULL        | NULL        |         | "BTREE"
"80700"      | "village"                  | "1"        | "sub_district_id"     | "1"          | "sub_district_id"     | "A"        | "13450"     | NULL        | NULL        |         | "BTREE"

score 0 · Accepted Answer

我会运行两个查询，一个有 acount(*)且没有限制，另一个没有 sub-select 并且没有SQL_CALC_FOUND_ROWS. 我必须分批查询大约 90k 行，并且还知道总数，这就是我最终要做的。

计数：

SELECT count(*) from (
(SELECT R.id, R.first_name, R.last_name, R.status
FROM REGISTERED R
WHERE R.status = 2)
UNION ALL
(SELECT PR.id, PR.first_name, PR.last_name, PR.status
FROM PRE_REGISTERED PR
WHERE PR.status = 3)) t;

实际数据：

(SELECT R.id, R.first_name, R.last_name, R.status
FROM REGISTERED R
WHERE R.status = 2)
UNION ALL
(SELECT PR.id, PR.first_name, PR.last_name, PR.status
FROM PRE_REGISTERED PR
WHERE PR.status = 3)
ORDER BY id LIMIT 0, 10

您还可以将其分解为 3 个查询、2 个计数和 1 个数据，然后将这两个计数相加。

score 0 · Accepted Answer

我想我找到了缓慢的因素。正是这部分让整个查询变慢了。这个变量是一个别名，它是一个公式。

ORDER BY .... U.min_pp_distance

虽然我还没有找到解决方法，但这证实了问题： MySQL-Performance when ordering on computed column

score 0 · Accepted Answer

使用OFFSETand LIMITwithUNION时，模式如下：

( SELECT ...
    ORDER BY x  -- required
    LIMIT 130   -- outer OFFSET + LIMIT
) UNION ALL     -- DISTINCT might work, too
( SELECT ...
    ORDER BY x  -- required
    LIMIT 130   -- outer OFFSET + LIMIT
)
ORDER BY x      -- again
LIMIT 120, 10   -- outer OFFSET and LIMIT

如果所有（或仅部分）子查询之一具有所需的行，则 120+10 就足够了。

到处都ORDER BY需要这样做，以便您选择正确的行。

同时，我不相信SQL_CALC_FOUND_ROWS能给你正确的答案。请参阅 http://dev.mysql.com/doc/refman/5.6/en/information-functions.html并搜索“联合”。此外，5.7.5 修复了“带有 SQL_CALC_FOUND_ROWS 的 UNION ALL 查询和带有一个查询块偏移量的 LIMIT 报告的找到的行数不正确。（错误 #17833261）”

附加物

添加SQL_CALC_FOUND_ROWS到第一个SELECT，使用ALL. 看看是否FOUND_ROWS()给你正确的答案。如果你不能使用ALL，或者如果LIMITs搞砸了CALC，那么我建议你在构建页面的同时不能得到答案。

如果没有其他原因，您的查询必须ORDER BY RAND()查看所有数据。也就是说，即使某些索引可以加快速度，它们也不能使大量数据的获取短路。

mysql - UNION 上的 SQL_CALC_FOUND_ROWS 以获取总行，但子查询上有 LIMIT

我将在这里展示我的架构

3 回答 3

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