The thing which is giving me some perplexity is that before the upgrade to a new version of the software which is using this DB...
Not perplexing at all. Someone wrote some code that relies more heavily on statistics or has become more sensitive to a thing known as "Parameter Sniffing". It happens and, if it's 3rd party software, you don't have many choices. Either get them to "fix" it or you need to deal with it, which might require you to rebuild the indexes more often than you have in the past.
is pronounced ree-bar and is a Modenism for R
First step towards the paradigm shift of writing Set Based code: Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
If you think its expensive to hire a professional to do the job, wait until you hire an amateur. -- Red Adair
How to post code problemsHow to post performance problemsForum FAQs