SugarCRM and Microsoft SQL Server. It is one of those subjects that seems to be surrounded by a lot of mystery -- and misinformation.
As I mention in my book, Implementing SugarCRM 5.x, there is nothing inherently wrong with using Microsoft SQL Server (MS-SQL) in conjunction with SugarCRM. There are certainly unique issues to be mindful of, but that is not any different than any other software.
Because the vast majority of the SugarCRM user community utilizes MySQL, instead of MS-SQL, these unique issues tend to have a mysterious aura about them, leading some to believe they cannot be overcome. I would argue most of that perception is the result of lack of exposure to the platform and to some extent, the rivalry between open and closed source software. In my experience, while solutions to some of the issues can be difficult or tedious to implement, there are fixes for the vast majority of the common problems.
Perhaps one of the trickier issues to address in such environments is the issue of performance, or lack thereof. It is worth noting that performance is a tricky subject regardless of which CRM solution we are discussing, so do not take my comment as a knock on SugarCRM. That being said, there is one specific issue that comes up on a regular basis and has a significant impact on performance.
Before we get into the details of the matter, it is important to note that many SugarCRM installations will never encounter the problem. The reason for this requires us to review some SugarCRM development history.