SQL 2005 - SELECT query takes long time to retrieve

Question

Post reply

SQL 2005 - SELECT query takes long time to retrieve

balasach82

SSCrazy Eights

Points: 9653
More actions
July 20, 2010 at 6:58 am

#141226

SQL 2005 - SELECT query takes long time to retrieve records from a table which has about 250000 records. Even a top 10 takes 4 to 5 mins. Any remedial measures?

Viewing 14 posts - 1 through 13 (of 13 total)

You must be logged in to reply to this topic. Login to reply

SQLBalls SSCarpal Tunnel Points: 4621 More actions · Answer 1

When you take a look at the execution plan what do you see?

Twitter: @SQLBalls
Blog: http://www.SQLBalls.com
Channel: https://www.youtube.com/@Tales-from-the-Field

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 2

balasach82 (7/20/2010)
SQL 2005 - SELECT query takes long time to retrieve records from a table which has about 250000 records. Even a top 10 takes 4 to 5 mins. Any remedial measures?

Not without seeing the query, no. You will get some help if you post the query.

You will get better help if you post the execution plans as already suggested.

For the best help, post the table definition as well, including any indexes, triggers etc along with some sample data.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

balasach82 SSCrazy Eights Points: 9653 More actions · Answer 3

select * from table_name where [time] between

'2009/6/1 6:00am' and '2009/6/30'

no indexes,triggers etc. Field [time] has datatype datetime.

Feeg SSCrazy Points: 2766 More actions · Answer 4

how many columns and rows is there in this table?

if it's a small table it should not take long to display the table at all without indexes on it ...

MCITP: Database Administrator 2005
MCTS SQL Server 2008
MCP SQL 2012/2014
MCSA SQL Server 2012/2014
MCSE Data Management and Analytics

balasach82 SSCrazy Eights Points: 9653 More actions · Answer 5

33 columns and aboutn 250,000 rows.

Execution plan shows Table Scan as 100%. Let me know if any more info is needed

SQLBalls SSCarpal Tunnel Points: 4621 More actions · Answer 6

Right click in your query window.

click Include Actual Execution Plan

when you execute the query next there will be an addition info that shows the Graphical query execution plan.

you probably could benefit from a non-clustered index on your date field, or a covering index if the data types are not to large.

here is a good tutorial on query optimization.

http://www.simple-talk.com/sql/performance/execution-plan-basics/

Twitter: @SQLBalls
Blog: http://www.SQLBalls.com
Channel: https://www.youtube.com/@Tales-from-the-Field

balasach82 SSCrazy Eights Points: 9653 More actions · Answer 7

I had created an index the time column.. but since the query took long time to complete, i dropped that index...

As mentioned the Exec plan shows 100% table scan

SQLBalls SSCarpal Tunnel Points: 4621 More actions · Answer 8

does the table have a clustered index?

you cannot do a covering index as the limit is 16 columns, I would deffinitally add a clustered and re-create a non clustered on time.

Twitter: @SQLBalls
Blog: http://www.SQLBalls.com
Channel: https://www.youtube.com/@Tales-from-the-Field

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 9

Bradley B (7/20/2010)
you cannot do a covering index as the limit is 16 columns,

The 16 column limit is only on key columns, not on include columns.

balasach, please post table definitions, index definitions and execution plan, as per http://www.sqlservercentral.com/articles/SQLServerCentral/66909/

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

SQLBalls SSCarpal Tunnel Points: 4621 More actions · Answer 10

Learn something new every day....and man there is a lot to learn.

the limit on include columns is 1023.

http://msdn.microsoft.com/en-us/library/ms190806.aspx

I stand corrected, when you remake the non clustered index I would make it a covering index over the select statement.

But 1st I'd do what Gail had suggested.

Twitter: @SQLBalls
Blog: http://www.SQLBalls.com
Channel: https://www.youtube.com/@Tales-from-the-Field

Roopesh Kumar Old Hand Points: 382 More actions · Answer 11

Create a non clustered index on the field [Time] and then execute the query again.

You should have a clustered index on the table also.

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 12

Please note: 2 year old thread.

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

balasach82 SSCrazy Eights Points: 9653 More actions · Answer 13

Thanks Roopesh,

As Gail said, been long time since i posted the issue. I resolved it, but dont rememeber how i did it then. In any case, will remember all the options posted in this thread for future.

IMHO, i think such replies to older posts, would be helpful to some other lost souls (even if the original person who posted stopped following the thread).