Our TFS database size was growing really quick and I figured out that the issue was with tbl_TestResult table. I am not sure why it is growing that fast. It seems there will be a record for each test case. In my case, we have more than 1000 test cases that will be fired in each check-in. That means we do average 20 check-ins a day. That is around 20,000 records.
My question is can I manually delete the records on that table? Will it make any problems to the TFs other than losing the tests results?
UPDATE:
We have TFS 2015
Deleting data manually or changing the schema in any way would result in your TFS instance no longer being supportable by Microsoft. It effectively invalidates your warranty.
In TFS 2015 you can change the Test Management retention settings in the Team Project admin page. Default is 30 days, but someone may have changed it.
Other than that this is the normal meta data that is collected as part of your ALM/DevOps platform. **