This query runs slower than expected

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This query runs slower than expected

anusha_yapa

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Points: 3
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September 6, 2010 at 1:42 pm

#140411

This query runs slower than expected (compared to other similar queries on the same database and tables)
Eg.
Select table1.x, table2.y from table1 join table2 on table1.a = table2.b
What are some likely cause of the problem.

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WayneS SSC Guru Points: 95461 More actions · Answer 1

No where clause.

No index on the columns being joined.

No index on the columns in the where clause (just in case you didn't specify it in your post).

Using functions on columns in either the join or where clauses.

Statistics out of date.

Edit: You might want to look at the "Performance Problems" link in my signature.

Wayne
Microsoft Certified Master: SQL Server 2008
Author - SQL Server T-SQL Recipes

If you can't explain to another person how the code that you're copying from the internet works, then DON'T USE IT on a production system! After all, you will be the one supporting it!

Links:
For better assistance in answering your questions
Performance Problems
Common date/time routines
Understanding and Using APPLY Part 1 & Part 2

pokemont17 Newbie Points: 3 More actions · Answer 2

anusha_yapa (9/6/2010)
This query runs slower than expected (compared to other similar queries on the same database and tables)
Eg.
Select table1.x, table2.y from table1 join table2 on table1.a = table2.b
What are some likely cause of the problem.

Great post! It's very nice. Thank you so much for your post.

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