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Optimizing delete SQL
Message
From
17/02/2011 15:35:19
James Blackburn
Qualty Design Systems, Inc.
Kuna, Idaho, United States
 
General information
Forum:
Microsoft SQL Server
Category:
SQL syntax
Environment versions
SQL Server:
SQL Server 2008
Application:
Web
Miscellaneous
Thread ID:
01500559
Message ID:
01500597
Views:
43
>>In this case, I don't see a lot of queries unless I misunderstand what a hit table is.
>>
>
>Take a look at this short blog post

I agree that every table should have a PK. I don't agree that every table should have a clustered index. Clustered indexes create more overhead and if your queries don't benefit from the index then there is no need for the extra overhead. JMHO

>
>Best Practice: Every table should have a primary key
>
>
>>>To speed up queries :-)
>>>But it takes its price when you insert/delete big amount of data.
>>>
>>>>Maybe a dumb question but why have a clustered index?
>>>>
>>>>>>I am looking to see if there could be a way to optimize a delete SQL I have.
>>>>>>
>>>>>>Basically, I do something like this every 15 minutes:
>>>>>>
>>>>>>
>>>>>>DELETE FROM Hit WHERE AddDate<something
>>>>>>
>>>>>>
>>>>>>As this is executed every 15 minutes, usually, this is executed in a flash. So, all records from the Hit table which are older than the parameter will be removed. The situation is when I run this command on a test server, where this procedure hasn't been executed since a while, the process may take several minutes.
>>>>>>
>>>>>>Is it because I am working on a date field? If yes, I can do a SQL at first to get the primary key and then remove anything older than that primary key.
>>>>>>
>>>>>>Or, is it that it is because there are a lot of records? If this is the case, what can I do to optimize?
>>>>>
>>>>>As I saw from the Execution plat the most part of the operation if for recreating the clustered index.
>>>>>Could you try to remove the index first then DELETE and then recreate it?
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