If they really cared about tax payers cash
...they wouldn't waste IT time on FOI requests that are blatant market research with a view to selling us their wonder product.
We don't buy a database first then look for the application to put on it, we'll buy the software service that meets the business needs and go with the supported database from that supplier.
I can see it now; "your application meets our critical needs but could you port it to Tibero please?",
"you want what now ?, yes sure we can do that, it'll cost you £60K+ an extra £20K support per year"