MySQL Select Optimization Help?
This is a broad example of a SELECT query I use frequently on one of my sites. We are having very bad issues with slow load page times with our host, so I am trying to do everything I can to optimize every bit of code the site uses. I am no expert when it comes to MySQL, so I am hoping some of you may be of assistance. Here is the query I am trying to optimize a bit more -
Select ID, Col1, Col2, Col3, Col4, Col5, Col6, Col7, Col8, Col9, Col10, Col11, Col12, Col13, Col14, Col15 From table_1
Where Active = '1' And Col2 LIKE '%Cat%' And Col3 <> 'blah' And Col3 <> 'blah1' And Col3 <> 'blah2' And Col3 <> 'blah3' And Col3 <> 'blah4' And Col3 <> 'blah5' And Col3 <> 'blah6'
And ID Not In (Select t2ID From table_2 Where table_2.t2ID = table_1.ID And table_2.Col1 = '1' And table_2.Col2 = '1')
And ID Not In (Select t3ID From table_3 Where table_3.t3ID = table_1.ID And table_3.Col1 = '1')
And ID Not In (Select t4ID From table_4 Where table_4.t4ID = table_1.ID And table_4.Col1 = '1')
Basically it checks 1 table (table_1) and pulls all the rows that match that are not found in table_2, table_3, and table_4. I am sure there is a much more efficient way to do this other than multiple sub selects. Any help is greatly appreciated! Thanks in advance :)
UPDATE: Basically all I am curious to find out is, is there something quicker than the multiple sub selects in the query? I am sure that there is some way to get the results from one table that do not exist in multiple other tables that is a lot more efficient than doing sub selects... The only commonality between the tables is that the ID from table_1, is identical to another column in each of the other 3 tables (which is what I am currently checking it against now using the sub selects). Unfortunately, I just cant figure out what the more efficient way to do this query is... Thanks for everyone's input thus far!
TABLE LAYOUT
mysql> show create table campaigns\G
*************************** 1. row ***************************
Table: campaigns
Create Table: CREATE TABLE `campaigns` (
`ID` int(11) NOT NULL auto_increment,
`CreatedOn` datetime NOT NULL,
`AddedBy` varchar(75) default NULL,
`pCampaignName` varchar(255) default NULL,
`CampaignName` varchar(255) default NULL,
`CampaignValue` decimal(65,2) default '0.00',
`CampaignPayout` decimal(65,2) NOT NULL default '0.00',
`CampaignT` double NOT NULL default '0',
`CampaignSD` double NOT NULL default '0',
`ReportingTime` varchar(255) default NULL,
`CampaignExpiration` varchar(100) default NULL,
`DurationType` varchar(100) default NULL,
`Countries` varchar(100) default NULL,
`CampaignDescription` longtext,
`CampaignRequirements` longtext,
`CampaignType` varchar(50) default NULL,
`CampaignID` varchar(255) default NULL,
`BannerImageWidth` int(10) NOT NULL default '0',
`BannerImageHeight` int(10) NOT NULL default '0',
`BannerImageURL` varchar(255) default NULL,
`BannerImageAlternateText` varchar(255) default NULL,
`DisplayBanner` int(1) NOT NULL default '0',
`CampaignCode` longtext,
`CampaignURL` longtext,
`CampaignActive` int(1) NOT NULL default '0',
`Status` varchar(255) default NULL,
`Affiliate` varchar(255) default NULL,
`NewOfferEmailSent` int(1) unsigned NOT NULL default '0',
`NumberApproved` double(65,2) NOT NULL default '0.00',
`NumberLeads` double NOT NULL default '0',
`ThumbsUp` double NOT NULL default '0',
`ThumbsDown` double NOT NULL default '0',
`CampaignPoints` double NOT NULL default '0',
`UserRatingUp` double NOT NULL default '0',
`UserRatingDown` double NOT NULL default '0',
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=1608 DEFAULT CHARSET=utf8
1 row in set (0.09 sec)
mysql> show indexes from campaigns\G
*************************** 1. row ***************************
Table: campaigns
Non_unique: 0
Key_name: PRIMARY
Seq_in_index: 1
Column_name: ID
Collation: A
Cardinality: 1596
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
1 row in set (0.10 sec)
mysql>
mysql> show create table acampaigns\G
*************************** 1. row ***************************
Table: acampaigns
Create Table: CREATE TABLE `acampaigns` (
`ID` int(11) NOT NULL auto_increment,
`CreatedOn` datetime NOT NULL,
`CampaignName` varchar(255) default NULL,
`CampaignRequirements` longtext,
`CampaignURL` longtext,
`CampaignValue` decimal(65,2) NOT NULL,
`CampaignPayout` decimal(65,2) NOT NULL,
`C开发者_开发知识库ampaignReferralCommissionTier1` decimal(65,2) NOT NULL default '0.20',
`CampaignReferralCommissionTier2` decimal(65,2) NOT NULL default '0.10',
`CampaignT` double NOT NULL default '0',
`CampaignSD` double NOT NULL default '0',
`CampaignType` varchar(255) default NULL,
`CampaignID` varchar(100) default NULL,
`CampaignExpiration` varchar(100) default NULL,
`CampaignReturnStatus` varchar(100) default NULL,
`CampaignStatus` varchar(255) default NULL,
`pCampaignID` int(11) NOT NULL,
`pCampaignName` varchar(255) default NULL,
`pUserID` int(11) NOT NULL,
`pUsername` varchar(75) default NULL,
`pUserIPAddress` varchar(30) default NULL,
`ApprovedOn` datetime NOT NULL,
`MarkedDone` int(1) NOT NULL default '0',
`Notes` longtext,
`PaidOn` datetime default NULL,
`cBonus` decimal(65,2) NOT NULL default '0.00',
`ReversedReason` varchar(255) default NULL,
`CampaignPoints` double NOT NULL default '0',
`Affiliate` varchar(255) default NULL,
`RC1Paid` int(1) unsigned NOT NULL default '0',
`RC2Paid` int(1) unsigned NOT NULL default '0',
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=10996 DEFAULT CHARSET=utf8
1 row in set (0.44 sec)
mysql> show indexes from acampaigns\G
*************************** 1. row ***************************
Table: acampaigns
Non_unique: 0
Key_name: PRIMARY
Seq_in_index: 1
Column_name: ID
Collation: A
Cardinality: 8936
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
1 row in set (0.09 sec)
mysql>
mysql> show create table bcampaigns\G
*************************** 1. row ***************************
Table: bcampaigns
Create Table: CREATE TABLE `bcampaigns` (
`ID` int(11) NOT NULL auto_increment,
`CreatedOn` datetime NOT NULL,
`pCampaignID` int(11) NOT NULL,
`ReportedByUserID` int(11) NOT NULL,
`Status` varchar(255) default NULL,
`Notes` longtext,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=375 DEFAULT CHARSET=utf8
1 row in set (0.08 sec)
mysql> show indexes from bcampaigns\G
*************************** 1. row ***************************
Table: bcampaigns
Non_unique: 0
Key_name: PRIMARY
Seq_in_index: 1
Column_name: ID
Collation: A
Cardinality: 0
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
1 row in set (0.08 sec)
mysql>
mysql> show create table icampaigns\G
*************************** 1. row ***************************
Table: icampaigns
Create Table: CREATE TABLE `icampaigns` (
`ID` int(11) NOT NULL auto_increment,
`CreatedOn` datetime NOT NULL,
`pCampaignID` int(11) default NULL,
`IgnoredByUserID` int(11) default NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=567 DEFAULT CHARSET=utf8
1 row in set (0.09 sec)
mysql> show indexes from icampaigns\G
*************************** 1. row ***************************
Table: icampaigns
Non_unique: 0
Key_name: PRIMARY
Seq_in_index: 1
Column_name: ID
Collation: A
Cardinality: 532
Sub_part: NULL
Packed: NULL
Null:
Index_type: BTREE
Comment:
1 row in set (0.40 sec)
mysql>
mysql> explain Select ID, CreatedOn, pCampaignName,
CampaignName, CampaignRequirements, CampaignURL, Countries,
CampaignPayout, CampaignPoints, CampaignT, CampaignSD, CampaignType,
ReportingTime, NumberApproved, NumberLeads
From campaigns
-> Where CampaignActive = '1' And CampaignType LIKE 'Cat%'
And CampaignType <> 'DS' And CampaignType <> 'CC' And CampaignType <> 'PC'
And CampaignType <> 'PC2' And CampaignType <> 'GCC' And CampaignType <> 'G'
And CampaignType <> 'R'
-> And ID Not In (Select pCampaignID From acampaigns
Where campaigns.ID = acampaigns.pCampaignID And MarkedDone = '1' And campaigns.pUserID = '1')
-> And ID Not In (Select pCampaignID From bcampaigns
Where bcampaigns.pCampaignID = campaigns.ID And bcampaigns.ReportedByUserID = '1')
-> And ID Not In (Select pCampaignID From icampaigns
Where icampaigns.pCampaignID = campaigns.ID And icampaigns.IgnoredByUserID = '1')
Have you tried to EXPLAIN your query. If you aren't familiar with EXPLAIN, it will produce a report showing how the query is performed and especially which indexes are used, and may show up where an index is desirable but not present.
I have also found in the past that NOT IN can sometimes be horrendously slow. Perhaps rewriting NOT IN as NOT EXISTS may speed things up.
NOT EXISTS (SELECT *
FROM table_3
WHERE table_3.t3ID = table_1.ID AND
table_3.Col1 = '1')
IDFMA
please post the results of the following script so we can analyse your query in detail. if you could also pastebin the results in say http://pastie.org/ that would be great too.
thanks
show create table table_1\G
show indexes from table_1\G
show create table table_2\G
show indexes from table_2\G
show create table table_3\G
show indexes from table_3\G
show create table table_4\G
show indexes from table_4\G
explain
Select
ID, Col1, Col2, Col3, Col4, Col5, Col6, Col7,
Col8, Col9, Col10, Col11, Col12, Col13, Col14, Col15
From
table_1
Where
Active = '1' And
Col2 LIKE '%Cat%' And Col3 <> 'blah' And Col3 <> 'blah1' And Col3 <> 'blah2' And Col3 <> 'blah3' And
Col3 <> 'blah4' And Col3 <> 'blah5' And Col3 <> 'blah6' And
ID Not In (Select t2ID From table_2 Where table_2.t2ID = table_1.ID And table_2.Col1 = '1' And table_2.Col2 = '1') And
ID Not In (Select t3ID From table_3 Where table_3.t3ID = table_1.ID And table_3.Col1 = '1') And
ID Not In (Select t4ID From table_4 Where table_4.t4ID = table_1.ID And table_4.Col1 = '1');
You can split this single query into multiple separate steps and put them in a single stored procedure using temporary tables. This will make it more readable and probably run faster...
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