I have an installation with two Dbs which should be identical in structure on the same SQL Server running two different companies. One of these is significantly larger than the other.
On the smaller of the two timeout errers have started to appear on queries which return results instantly to the users of the other Db which has about 4 times the number of rows in each table.
Something is wrong but I don't know where to begin. I have tried copying the query to a file and running the tuning advisor but it comes up with Error Unable to open input file on the Consuming Workload section.