mysql命令通過優化連接和哪來

Question

我有這個疑問：

SELECT SQL_NO_CACHE DISTINCT `photos`.* 
FROM `photos` 
INNER JOIN `locations` ON `photos`.`location_id` = `locations`.`id` 
LEFT OUTER JOIN `albums_photos` ON `photos`.`id` = `albums_photos`.`photo_id` 
LEFT OUTER JOIN `facets` ON `photos`.`id` = `facets`.`photo_id` 
LEFT OUTER JOIN `source_tags` ON `facets`.`source_id` = `source_tags`.`id` 
LEFT OUTER JOIN `source_comments` ON `facets`.`source_id` = `source_comments`.`id` 
WHERE (`photos`.`date_taken` <= '2017-08-24') 
AND (photos.status != 1 or photos.status is NULL) 
ORDER BY `photos`.`date_taken` DESC 
LIMIT 75 
OFFSET 0 

它需要這需要6-7秒來運行。當我拿出Order by子句時：

SELECT SQL_NO_CACHE DISTINCT `photos`.* 
FROM `photos` 
INNER JOIN `locations` ON `photos`.`location_id` = `locations`.`id` 
LEFT OUTER JOIN `albums_photos` ON `photos`.`id` = `albums_photos`.`photo_id` 
LEFT OUTER JOIN `facets` ON `photos`.`id` = `facets`.`photo_id` 
LEFT OUTER JOIN `source_tags` ON `facets`.`source_id` = `source_tags`.`id` 
LEFT OUTER JOIN `source_comments` ON `facets`.`source_id` = `source_comments`.`id` 
WHERE (`photos`.`date_taken` <= '2017-08-24') 
AND (photos.status != 1 or photos.status is NULL) 
LIMIT 75 
OFFSET 0 

運行需要0.025秒。所以顯然沒有優化。 我有照片，這些指標

Table, Non_unique, Key_name, Seq_in_index, Column_name, Collation, Cardinality, Sub_part, Packed, Null, Index_type, Comment, Index_comment 
photos, 0, PRIMARY, 1, id, A, 21069, , , , BTREE, , 
photos, 1, index_photos_on_location_id, 1, location_id, A, 468, , , YES, BTREE, , 
photos, 1, index_photos_on_date_taken, 1, date_taken, A, 21069, , , YES, BTREE, , 
photos, 1, index_photos_on_status, 1, status, A, 2, , , YES, BTREE, , 
photos, 1, index_photos_on_phash, 1, phash, A, 21069, , , YES, BTREE, , 

照片設置爲每個：

Field, Type, Null, Key, Default, Extra 
id, bigint(20), NO, PRI, , auto_increment 
date_taken, datetime, YES, MUL, , 
created_at, datetime, NO, , , 
updated_at, datetime, NO, , , 
file_extension, varchar(255), YES, , , 
file_size, int(11), YES, , , 
location_id, bigint(20), YES, MUL, , 
make, varchar(255), YES, , , 
model, varchar(255), YES, , , 
original_height, int(11), YES, , , 
original_width, int(11), YES, , , 
longitude, decimal(16,10), YES, , , 
latitude, decimal(16,10), YES, , , 
status, int(11), YES, MUL, 0, 
phash, varchar(255), YES, MUL, , 
org_id, int(11), YES, , , 
lg_id, int(11), YES, , , 
md_id, int(11), YES, , , 
tm_id, int(11), YES, , , 

我能做些什麼。我應該在我的應用程序（rails或JS）中進行排序嗎？

- 編輯 -

我要補充的是，當我拿出所有的聯接，但離開的時候訂單下降到低於秒。讓我覺得我需要在連接的列和date_taken之間的索引？

SELECT SQL_NO_CACHE DISTINCT `photos`.* 
FROM `photos` 
WHERE (`photos`.`date_taken` <= '2017-08-24') 
AND (photos.status != 1 or photos.status is NULL) 
#AND (`photos`.`date_taken` is not null) 
ORDER BY `photos`.`date_taken` DESC 
LIMIT 75 
OFFSET 0; 

Answer 1

如果表包含PK（例如：一個id AUTO_INCREMENT）的distinct photos.*是無用
不同於其它各行ID

除去無用（）在條件

和記該限制適用於在行被檢索並排序之後（對於此嘗試移除限制和測試偏移）

SELECT SQL_NO_CACHE `photos`.* 
FROM `photos` 
INNER JOIN `locations` ON `photos`.`location_id` = `locations`.`id` 
LEFT JOIN `albums_photos` ON `photos`.`id` = `albums_photos`.`photo_id` 
LEFT JOIN `facets` ON `photos`.`id` = `facets`.`photo_id` 
LEFT JOIN `source_tags` ON `facets`.`source_id` = `source_tags`.`id` 
LEFT JOIN `source_comments` ON `facets`.`source_id` = `source_comments`.`id` 
WHERE `photos`.`date_taken` <= '2017-08-24' 
AND (photos.status != 1 or photos.status is NULL) 
ORDER BY `photos`.`date_taken` DESC 
LIMIT 75 
OFFSET 0 

確保你對所有連接columun和外鍵 並在所有適當的指數photos.date_taken和photos.status

你也可以使用一個綜合指數(photos.date_taken ,photos.status)

Answer 2

像這樣試一下。發現了類似的問題並修復了它。

SELECT * FROM(
SELECT SQL_NO_CACHE DISTINCT `photos`.* 
FROM `photos` 
INNER JOIN `locations` ON `photos`.`location_id` = `locations`.`id` 
LEFT OUTER JOIN `albums_photos` ON `photos`.`id` = `albums_photos`.`photo_id` 
LEFT OUTER JOIN `facets` ON `photos`.`id` = `facets`.`photo_id` 
LEFT OUTER JOIN `source_tags` ON `facets`.`source_id` = `source_tags`.`id` 
LEFT OUTER JOIN `source_comments` ON `facets`.`source_id` = `source_comments`.`id` 
WHERE (`photos`.`date_taken` <= '2017-08-24') 
AND (photos.status != 1 or photos.status is NULL) 
)ORDER BY `photos`.`date_taken` DESC 
LIMIT 75 
OFFSET 0