Execution plan different on two different Sql Servers

Posted by Lieven Cardoen on Server Fault See other posts from Server Fault or by Lieven Cardoen
Published on 2010-03-20T09:12:49Z Indexed on 2010/03/20 9:21 UTC
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On our sql server, a query takes 20 ms. If I look at the execution plan, parallelism is used, hash match, Bitmap create, ... a lot of images with two arrows pointing to the left.

On sql server of a customer where our product runs, the same query takes 2500 ms. If I look at their execution plan, no parallelism or any of the things with arrows are used...

I've been searching for a couple of days no why the query runs so much slower on their sql server.

  • Is parallelism and all of the other things something that can be configured on their sql server?
  • And how to you configure that?
  • What are the dangers of using parallelism?

Another strange thing is that on our server, the query needs some 1200 reads and 0 writes. On their sql server it needs 1.5 million reads and some 1500 writes. Why these writes when a read query is done?

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