Query Performance improvement

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SQL-Server-2005

Below is my query

SQL

SELECT Month(StartUtc),Year(EndUtc),Count(ID1),Count(ID2),Count(ID3)
FROM Employee WHERE Creditnumber='95A60378-0ECC-4D23-804F-71BB2BADED08'
 AND AssemblyId='B3468D54-EC5A-4C49-9DB0-F2B9651E78A2' 
AND StartUtc Between '2010-01-01' AND '2010-12-31'
Group By Month(StartUtc),Year(StartUtc)

There are non clustor index present on table Employee for Creditnumber,AssemblyId,StartUtc
StartUtc is of datetime datatype , All are the IDs are of BigInt datatype ,
and Creditnumber,AssemblyId are Uniqueidentifier datatype.
All is set with respect to performance tunning but still the query take 9 min to return result.
BTW Employee contains 25K rows.
I have tried force index also on the query but no improvement in performance
Please suggest me any way to improve performance further.

Posted 27-Jun-11 4:24am

RDBurmon

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hitesh_tech 27-Jun-11 11:18am

How many records are in employee table approximately?

Dylan Morley 27-Jun-11 11:21am

He mentions that - 25K rows

2 solutions

Solution 1

I would start by trying to find out what is causing it to be so slow:
Isolate the query in a separate application, so there are no other effects on it.
Time the query as is. If it is significantly different from teh your-app version, find out why.
Cut the query to the bone.

SELECT MONTH(StartUtc) FROM Employee WHERE Creditnumber='95A60378-0ECC-4D23-804F-71BB2BADED08'

Time it.
If it is fast, keep adding bits of the query back until it is slow - then you can work on improving performance of the last bit you added.

Sorry, but you need to find out where your problem is, before you can fix it!

Posted 27-Jun-11 5:16am

OriginalGriff

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Dylan Morley · Accepted Answer · 2011-06-27T05:26:00

Open SQL Management studio, choose 'New Query' and paste in your SQL statement to the window.

Now choose Query -> display estimated execution plan.

Your query plan is displayed. Pay attention here - these are the steps to it returning your data. Look out for steps with a high % of cost to the overall query execution.

E.g. cost 98% - you know this is where all the time in your query is being spent!

Can you see anything in here? Is it correctly using your index, or do you see any Table Scans?