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Order By Slows down Joins
Posted by: Sami BH
Date: August 22, 2012 09:12AM

Hello,

I have problem with this query

SELECT *
FROM files f
LEFT JOIN xfiles x ON x.hash = f.bhash
LEFT JOIN cate c ON c.id = f.cate
LEFT JOIN users u ON u.id = f.user
LEFT JOIN userslev ul ON u.id_lev = ul.id
LEFT JOIN (

SELECT DISTINCT x.hash, s.iis
FROM anno x
JOIN seb s ON s.iis = x.icc
WHERE x.le =0
AND (
x.eve =0
OR x.eve =2
)
GROUP BY `x`.`hash`
) AS tabel2 ON tabel2.hash = f.bhash
WHERE f.see + IFNULL( x.see, 0 ) + f.lee + IFNULL( x.lee, 0 ) >0
ORDER BY f.added DESC

Showing rows 0 - 29 ( 22,083 total, Query took 9.6523 sec)

as you can see , it takes 9 sec !

but without 'order by'

SELECT *
FROM files f
LEFT JOIN xfiles x ON x.hash = f.bhash
LEFT JOIN cate c ON c.id = f.cate
LEFT JOIN users u ON u.id = f.user
LEFT JOIN userslev ul ON u.id_lev = ul.id
LEFT JOIN (

SELECT DISTINCT x.hash, s.iis
FROM anno x
JOIN seb s ON s.iis = x.icc
WHERE x.le =0
AND (
x.eve =0
OR x.eve =2
)
GROUP BY `x`.`hash`
) AS tabel2 ON tabel2.hash = f.bhash
WHERE f.see + IFNULL( x.see, 0 ) + f.lee + IFNULL( x.lee, 0 ) >0


Showing rows 0 - 29 ( 22,083 total, Query took 0.0241 sec)

only 0.0241 sec :)

............

is there a way to have ' order by' with good-time?

............

indexes:


Indexes: (files)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No ihash 27815 A
Edit Drop filename BTREE No No filename 27815 A
Edit Drop cate BTREE No No cate 45 A
Edit Drop user BTREE No No user 1264 A
Edit Drop bhash BTREE No No bhash (20) 27815 A
Edit Drop added BTREE No No added 27815 A
Edit Drop filename_2 FULLTEXT No No filename 1



Indexes: (xfiles)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No id 8196 A
Edit Drop hash BTREE Yes No hash 8196 A
Edit Drop see BTREE No No see 37 A
Edit Drop leec BTREE No No lee25 A


Indexes: (cate)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No id 51 A


Indexes: (users)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No id 39776 A
Edit Drop username BTREE Yes No username 39776 A
Edit Drop id_lev BTREE No No id_lev 19 A


Indexes: (userslev)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop base BTREE Yes No id 22 A


Indexes: (anno)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No id 23636 A
Edit Drop icc BTREE No No icc 2626 A
Edit Drop eve BTREE No No eve 8 A
Edit Drop hash BTREE No No hash 5909 A
Edit Drop le BTREE No No le 875 A


Indexes: (seb)

Action Keyname Type Unique Packed Column Cardinality Collation Null Comment
Edit Drop PRIMARY BTREE Yes No id 58 A
Edit Drop iis BTREE Yes No iis 58 A YES


EXPLAIN:

id select_type table type possible_keys key key_len ref rows Extra
1 PRIMARY f ALL NULL NULL NULL NULL 27819 Using temporary; Using filesort
1 PRIMARY x eq_ref hash hash 20 f.bhash 1 Using where
1 PRIMARY c eq_ref PRIMARY PRIMARY 4 f.cate 1
1 PRIMARY u eq_ref PRIMARY PRIMARY 4 f.user 1
1 PRIMARY ul eq_ref base base 4 u.id_lev 1
1 PRIMARY <derived2> ALL NULL NULL NULL NULL 1176
2 DERIVED s index iis iis 5 NULL 58 Using index; Using temporary; Using filesort
2 DERIVED x ref icc,eve,le icc 4 s.iis 9 Using where

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Order By Slows down Joins
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August 22, 2012 09:12AM
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