sql query performance

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SQL-Server-2005

SQL-Server

Hi,
Is there any sql query analyzer tool from where I can check which way is better.

Regards
Seema

Posted 26-Jan-11 2:06am

Seema Gosain

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**JF2015** · Answer 1 · 2011-01-26T02:09:00

Solution 1

See here:
http://msdn.microsoft.com/en-us/library/ms181091%28SQL.90%29.aspx[^]
http://msdn.microsoft.com/en-us/library/ms174173%28SQL.90%29.aspx[^]
http://msdn.microsoft.com/en-us/library/ms178071%28SQL.90%29.aspx[^]

Posted 26-Jan-11 2:09am

JF2015

Comments

Espen Harlinn 29-Jan-11 4:49am

5+ the profiler is your friend :)

Dylan Morley · Answer 2 · 2011-01-26T02:46:00

You can do a lot from within management studio, the third link posted by JF2015 is essential reading

If you've got the Northwind database, open a new query window against it and put in the following SQL

SQL

SELECT CustomerID, CompanyName
FROM dbo.Customers
WHERE City= 'London'

Now choose Query -> Display Estimated Execution Plan

The database engine will show you that for this query it will attempt to perform an Index Seek against the index named City

Now try the same thing with this SQL

SQL

SELECT * FROM  Orders O
WHERE ShipCity Like  '%London%'
ORDER BY OrderDate

You'll notice this time it's performing an Index Scan (80% of total query Cost) and a Sort (20%).

Depending on the amount of rows in the table, you would generally want to avoid a Scan. The engine has to analyse all the rows in the table to determine which rows qualify for your statement

http://blog.sqlauthority.com/2007/03/30/sql-server-index-seek-vs-index-scan-table-scan/[^]

The execution plan window is a really useful part of SQL Server, you should get used to checking SQL statements here.