MySQL通过联接和位置进行优化排序

Question

I have this query:

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

It takes which takes 6-7 sec to run. When I take out the Order by clause:

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

It takes 0.025 sec to run. So clearly something is not optimized. I have these indices on photos

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, , 

Photos is set up as per:

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, , , 

what can I do. Should I do the ordering in my app (rails or JS)?

-- EDIT --

I should add that when I take out all the joins but leave in the order by the time drops to below a sec. Makes me think I need an index across the joined columns and date_taken??

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

if the tables contains a pk (eg: an id auto_increment) the distinct photos.* is unuseful
each row id different from the others

remove unuseful () in where condition

and remember that the limit is applied after al the rows are retrieved and ordered by (for this try removing limit and offset for test)

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

be sure you have proper index on all the join columun and foreign key and over all a proper index on photos.date_taken and photos.status

you could use also a composite index (photos.date_taken ,photos.status)

Answer 2

Try it like this.Faced a similar issue and fixed it like this.

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