Execution plan different on two different Sql Servers
- by Lieven Cardoen
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?