I have seen this happen many times. Lets talk about one of the decisions that really is covering a lot of blunders.
At my current company we are using Microsoft SQL Server as our Database. It is very fast as compared to other opensource solutions like MySQL. The reason why I am saying this is because in my previous company we were using MySQL. We had a Content Management System developed for it. So it is easy to imagine the volume of data we had and how much it mattered to retrieve data fast. In that application we wrote some of the most optimized queries, invested time in making indexes to make data retrieval fast, we used query hints so that proper indexes were utilized. Upgraded the servers to multiple processors, utilized a RAID at the backend to minimize disk I/O. In short we did whatever we could to make it fast.
Now if I compare that database we have at my current cmopany, there aren’t any indexes, not even primary keys and making foriegn key relationships is taken as a crime. no constraints no indexes, no query optimizations. But it works a lot fast than the optimized MySQL server. If I show the queries and schema of the database to some DBAdmin I am dead sure that he is going to pull out his hairs but the thing is our application is very FAST. In short MsSQL is saving our ass here.
So the leason is a good decision in the start of using MsSQL server id paying dividents. Altough people have abused the DB, they dont know how to utilize the DB but still the application is blazing fast. As compared with optimized MySQL, we had optimized queries, proper indexing and proper schema but still out application wasn’t upto the mark.
Indeed a good decision at the start is saving us otherwise we are doing our best to slow down the application.