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?