Comments on: MySQL – Simple ways to avoid filesort http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/ Everything In Life Is Random! (Personal and Work) Tue, 20 Mar 2012 23:49:01 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Deepu http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-13291 Deepu Tue, 28 Feb 2012 10:23:41 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-13291 Could you please help me to avoid filesort in the following query SELECT DISTINCT(storages.id), IF(admin_approve = 1 OR storage_free_auctions.user_id = 167 OR ISNULL(storage_free_auctions.user_id), auction_date, NULL) AS auction_date1 FROM user_list_storage JOIN storages ON storages.id = user_list_storage.storage_id JOIN states ON states.id = storages.state LEFT JOIN storage_auctions ON storage_auctions.id= ( SELECT storage_auctions.id FROM storage_auctions LEFT JOIN storage_free_auctions ON storage_free_auctions.storage_auctions_id=storage_auctions.id WHERE storage_auctions.storage_id = storages.id AND storage_auctions.status = 'Active' AND (ISNULL(storage_free_auctions.user_id) OR admin_approve = 1 OR storage_free_auctions.user_id = 167) AND CONCAT(auction_date,' ',start_time) >= CURDATE() ORDER BY auction_date ASC LIMIT 1) LEFT JOIN storage_free_auctions ON storage_free_auctions.storage_auctions_id=storage_auctions.id LEFT JOIN storage_auction_units ON storage_auction_units.storage_auction_id = storage_auctions.id AND storage_auction_units.status='Active' WHERE storages.storage_status = 'Active' AND user_list_storage.user_id = 167 AND user_list_storage.user_list_id = 3 AND (storage_free_auctions.user_id = 167 OR admin_approve = 1 OR ISNULL(storage_free_auctions.user_id) OR user_list_storage.user_id = 167) GROUP BY storages.id order by auction_date1 First row of the explain result is as follows. id : 1 Select_type : PRIMARY Table : user_list_storage Type : ref possible_keys : idx_user_list_id,idx_storage_id,idx_user_id key : idx_user_id key_len : 5 ref : const rows : 64 Extra : Using where; Using temporary; Using filesort Could you please help me to avoid filesort in the following query

SELECT DISTINCT(storages.id),
IF(admin_approve = 1 OR storage_free_auctions.user_id = 167 OR ISNULL(storage_free_auctions.user_id),
auction_date, NULL) AS auction_date1 FROM user_list_storage
JOIN storages ON
storages.id = user_list_storage.storage_id
JOIN states ON
states.id = storages.state
LEFT JOIN storage_auctions
ON storage_auctions.id= (
SELECT storage_auctions.id FROM storage_auctions LEFT JOIN storage_free_auctions ON storage_free_auctions.storage_auctions_id=storage_auctions.id
WHERE storage_auctions.storage_id = storages.id AND storage_auctions.status = ‘Active’ AND (ISNULL(storage_free_auctions.user_id)
OR admin_approve = 1
OR storage_free_auctions.user_id = 167)
AND CONCAT(auction_date,’ ‘,start_time) >= CURDATE() ORDER BY auction_date ASC LIMIT 1)
LEFT JOIN storage_free_auctions ON storage_free_auctions.storage_auctions_id=storage_auctions.id
LEFT JOIN storage_auction_units ON storage_auction_units.storage_auction_id = storage_auctions.id
AND storage_auction_units.status=’Active’ WHERE storages.storage_status = ‘Active’
AND user_list_storage.user_id = 167 AND user_list_storage.user_list_id = 3
AND (storage_free_auctions.user_id = 167
OR admin_approve = 1
OR ISNULL(storage_free_auctions.user_id)
OR user_list_storage.user_id = 167)
GROUP BY storages.id
order by auction_date1
First row of the explain result is as follows.

id : 1
Select_type : PRIMARY
Table : user_list_storage
Type : ref possible_keys : idx_user_list_id,idx_storage_id,idx_user_id key : idx_user_id key_len : 5 ref : const
rows : 64
Extra : Using where; Using temporary; Using filesort

]]> By: Free To Feel » Blog Archive » Mysql : Avoid Filesort http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-10204 Free To Feel » Blog Archive » Mysql : Avoid Filesort Thu, 03 Jun 2010 02:34:33 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-10204 [...] Reference [...] [...] Reference [...]

]]> By: Masao Kitamura » How To Use MySQL EXPLAIN http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-9722 Masao Kitamura » How To Use MySQL EXPLAIN Mon, 29 Mar 2010 00:28:29 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-9722 [...] also http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/ Categories: MySQL Tags: Comments (0) Trackbacks (0) Leave a comment [...] [...] also http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/ Categories: MySQL Tags: Comments (0) Trackbacks (0) Leave a comment [...]

]]> By: durga http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-9144 durga Wed, 25 Nov 2009 05:54:04 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-9144 explain SELECT SQL_CALC_FOUND_ROWS ops.node.node_id, ops.node.name AS nodename, ops.node.ytag, ops.node.status, ops.node.site_id, ops.node.parent_id, ops.site.name AS sitename, ops.property.prop_id, ops.property.name AS property_name, c.code AS country_code, d1.name AS node_type, ops.node.locroom, ops.node.loccage, ops.node.locarea, ops.node.locrow, ops.node.locrack, ops.node.locside, ops.node.locshelf, ops.node.bootbox_id, ops.node.bport, ops.node.bmodule, ops.node.bplug, ops.node.bootbox2_id, ops.node.bport2, ops.node.bmodule2, ops.node.bplug2, d2.name AS osname, ops.os.version AS osver, ops.node.racksize, ops.node.serialno, ops.node.console_id, ops.node.cport, ops.node.model_id, ops.model.name AS model_name, model.company_id, ops.company.name AS com_name, GROUP_CONCAT(DISTINCT ops.mac.mac ORDER BY ops.mac.mac SEPARATOR '|') AS mac, ops.node.c_time AS bornondate, UNIX_TIMESTAMP(ops.node.m_time) AS atime, FROM_UNIXTIME(ops.node.c_time) AS c_time, FROM_UNIXTIME(UNIX_TIMESTAMP(ops.node.m_time)) AS m_time, ops.node.ponumber, bp.name backplane, ops.node.pdu, ops.node.notes, nswitch.name as mswitchname, ops.node.sport as msport, nvs.validation_status_id, d3.name AS validation_status_name, d3.label AS validation_status FROM ops.node LEFT JOIN ops.property ON (node.prop_id = property.prop_id) LEFT JOIN ops.country c ON property.country_id = c.country_id LEFT JOIN ops.site ON (node.site_id = site.site_id) LEFT JOIN ops.dictionary AS d1 ON (node.type_id = d1.dict_id) LEFT JOIN ops.os ON (node.os_id = os.os_id) LEFT JOIN ops.dictionary AS d2 ON (os.dict_id = d2.dict_id) LEFT JOIN ops.model ON (node.model_id = model.model_id) LEFT JOIN ops.mac ON (mac.node_id = node.node_id) LEFT JOIN ops.company ON (model.company_id = company.company_id) LEFT JOIN ops.node AS nswitch ON (ops.node.netswitch_id = nswitch.node_id) LEFT JOIN ops.nodeValidationStatus AS nvs ON (node.node_id = nvs.node_id) LEFT JOIN ops.dictionary AS d3 ON (nvs.validation_status_id = d3.dict_id) LEFT JOIN ops.backplane as bp on (bp.backplane_id = node.backplane_id) WHERE ops.node.name '' AND ops.node.status = 'active' GROUP BY ops.node.node_id ORDER BY node.name LIMIT 0, 25; +----+-------------+----------+--------+-------------------+-----------+---------+------------------------------+------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------+--------+-------------------+-----------+---------+------------------------------+------+----------------------------------------------+ | 1 | SIMPLE | node | range | name | name | 257 | NULL | 4 | Using where; Using temporary; Using filesort | | 1 | SIMPLE | property | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.prop_id | 1 | | | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 4 | ops.property.country_id | 1 | | | 1 | SIMPLE | site | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.site_id | 1 | | | 1 | SIMPLE | d1 | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.type_id | 1 | | | 1 | SIMPLE | os | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.os_id | 1 | | | 1 | SIMPLE | d2 | eq_ref | PRIMARY | PRIMARY | 4 | ops.os.dict_id | 1 | | | 1 | SIMPLE | model | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.model_id | 1 | | | 1 | SIMPLE | mac | ref | node_id,node_id_2 | node_id_2 | 4 | ops.node.node_id | 18 | | | 1 | SIMPLE | company | eq_ref | PRIMARY | PRIMARY | 4 | ops.model.company_id | 1 | | | 1 | SIMPLE | nswitch | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.netswitch_id | 1 | | | 1 | SIMPLE | nvs | ref | node_id_2,node_id | node_id | 5 | ops.node.node_id | 15 | | | 1 | SIMPLE | d3 | eq_ref | PRIMARY | PRIMARY | 4 | ops.nvs.validation_status_id | 1 | | | 1 | SIMPLE | bp | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.backplane_id | 1 | | +----+-------------+----------+--------+-------------------+-----------+---------+------------------------------+------+----------------------------------------------+ I chnaged the orader by column with let joined table's field but does not works for me..still taking file sorting. explain SELECT SQL_CALC_FOUND_ROWS ops.node.node_id, ops.node.name AS nodename, ops.node.ytag, ops.node.status, ops.node.site_id, ops.node.parent_id, ops.site.name AS sitename, ops.property.prop_id, ops.property.name AS property_name, c.code AS country_code, d1.name AS node_type, ops.node.locroom, ops.node.loccage, ops.node.locarea, ops.node.locrow, ops.node.locrack, ops.node.locside, ops.node.locshelf, ops.node.bootbox_id, ops.node.bport, ops.node.bmodule, ops.node.bplug, ops.node.bootbox2_id, ops.node.bport2, ops.node.bmodule2, ops.node.bplug2, d2.name AS osname, ops.os.version AS osver, ops.node.racksize, ops.node.serialno, ops.node.console_id, ops.node.cport, ops.node.model_id, ops.model.name AS model_name, model.company_id, ops.company.name AS com_name, GROUP_CONCAT(DISTINCT ops.mac.mac ORDER BY ops.mac.mac SEPARATOR ‘|’) AS mac, ops.node.c_time AS bornondate, UNIX_TIMESTAMP(ops.node.m_time) AS atime, FROM_UNIXTIME(ops.node.c_time) AS c_time, FROM_UNIXTIME(UNIX_TIMESTAMP(ops.node.m_time)) AS m_time, ops.node.ponumber, bp.name backplane, ops.node.pdu, ops.node.notes, nswitch.name as mswitchname, ops.node.sport as msport, nvs.validation_status_id, d3.name AS validation_status_name, d3.label AS validation_status FROM ops.node LEFT JOIN ops.property ON (node.prop_id = property.prop_id) LEFT JOIN ops.country c ON property.country_id = c.country_id LEFT JOIN ops.site ON (node.site_id = site.site_id) LEFT JOIN ops.dictionary AS d1 ON (node.type_id = d1.dict_id) LEFT JOIN ops.os ON (node.os_id = os.os_id) LEFT JOIN ops.dictionary AS d2 ON (os.dict_id = d2.dict_id) LEFT JOIN ops.model ON (node.model_id = model.model_id) LEFT JOIN ops.mac ON (mac.node_id = node.node_id) LEFT JOIN ops.company ON (model.company_id = company.company_id) LEFT JOIN ops.node AS nswitch ON (ops.node.netswitch_id = nswitch.node_id) LEFT JOIN ops.nodeValidationStatus AS nvs ON (node.node_id = nvs.node_id) LEFT JOIN ops.dictionary AS d3 ON (nvs.validation_status_id = d3.dict_id) LEFT JOIN ops.backplane as bp on (bp.backplane_id = node.backplane_id) WHERE ops.node.name ” AND ops.node.status = ‘active’ GROUP BY ops.node.node_id ORDER BY node.name LIMIT 0, 25;
+—-+————-+———-+——–+——————-+———–+———+——————————+——+———————————————-+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+—-+————-+———-+——–+——————-+———–+———+——————————+——+———————————————-+
| 1 | SIMPLE | node | range | name | name | 257 | NULL | 4 | Using where; Using temporary; Using filesort |
| 1 | SIMPLE | property | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.prop_id | 1 | |
| 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 4 | ops.property.country_id | 1 | |
| 1 | SIMPLE | site | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.site_id | 1 | |
| 1 | SIMPLE | d1 | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.type_id | 1 | |
| 1 | SIMPLE | os | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.os_id | 1 | |
| 1 | SIMPLE | d2 | eq_ref | PRIMARY | PRIMARY | 4 | ops.os.dict_id | 1 | |
| 1 | SIMPLE | model | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.model_id | 1 | |
| 1 | SIMPLE | mac | ref | node_id,node_id_2 | node_id_2 | 4 | ops.node.node_id | 18 | |
| 1 | SIMPLE | company | eq_ref | PRIMARY | PRIMARY | 4 | ops.model.company_id | 1 | |
| 1 | SIMPLE | nswitch | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.netswitch_id | 1 | |
| 1 | SIMPLE | nvs | ref | node_id_2,node_id | node_id | 5 | ops.node.node_id | 15 | |
| 1 | SIMPLE | d3 | eq_ref | PRIMARY | PRIMARY | 4 | ops.nvs.validation_status_id | 1 | |
| 1 | SIMPLE | bp | eq_ref | PRIMARY | PRIMARY | 4 | ops.node.backplane_id | 1 | |
+—-+————-+———-+——–+——————-+———–+———+——————————+——+———————————————-+
I chnaged the orader by column with let joined table’s field but does not works for me..still taking file sorting.

]]> By: kareti ramakrishna http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-4425 kareti ramakrishna Tue, 17 Jun 2008 07:46:20 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-4425 Hi, Thanks for the information. Nice to know about you. All the Best Ramakrishna Hi,
Thanks for the information.
Nice to know about you.
All the Best
Ramakrishna

]]> By: Vladimir Kolesnikov http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/comment-page-1/#comment-4359 Vladimir Kolesnikov Tue, 10 Jun 2008 10:32:31 +0000 http://venublog.com/2007/11/29/mysql-how-to-avoid-filesort/#comment-4359 Venu, your suggestions could work in some cases, but they will not work in general. Let me show you some simple examples. 1. You cannot avoid filesort by simply including the order by column(s) into WHERE: SELECT col1 FROM testtab WHERE col1 > 1 OR col3 > 1 ORDER BY col3; 2. You not necessarily need to have ORDER BY column(s) in the WHERE clause: ALTER TABLE testtab ADD INDEX ix1 (col1, col3); SELECT col3 FROM testtab WHERE col1=1 ORDER BY col3; Also, storage engine does matter... :) BR Venu,

your suggestions could work in some cases, but they will not work in general. Let me show you some simple examples.

1. You cannot avoid filesort by simply including the order by column(s) into WHERE:
SELECT col1 FROM testtab WHERE col1 > 1 OR col3 > 1 ORDER BY col3;

2. You not necessarily need to have ORDER BY column(s) in the WHERE clause:
ALTER TABLE testtab ADD INDEX ix1 (col1, col3);
SELECT col3 FROM testtab WHERE col1=1 ORDER BY col3;

Also, storage engine does matter… :)

BR

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