We've started to get a number of request whether SQL Server Compact will support 64bit. The answer is absolutely YES! Ok, but when? We'll, that part we're working on. Up until recently, we haven't really seen a big need as the number of clients that have 64 bit hardware was fairly minimal at best. Even those that purchase 64 bit hardware may still load 32 bit operating systems as lots of software isn't 64 bit ready. Even if it was, it's not clear it would actually run faster. In some cases it may run slower. However, that being said, we do know that developers want their products Vista certified, and need 64bit support. So, similar to the 4gb limit questions, it seems developers just want to know whether it's an if, or a when. So, hear clearly, it's a when, not an if.
As for the answer, we're very focused on finishing up Visual Studio 2008 (Orcas) as well as SQL Server 2008 (Katmai). We hope to have some answers on "when" later this summer as we can rank the features and scenarios we're hearing from customers that they want us to add to SQLce and our end to end client offerings. Because 64bit isn't a feature, but rather another "platform", we don't necessarily need another release to ship SQL Server Compact 3.5 with 64 bit native support, we just need to finish up the work. So, one option is we ship 64 bit between 3.5 and our next release.
Now, I hope this post won't get twisted into one of those "Microsoft commitments to the 64 bit platform" rants. With a nimble team, we can easily adjust to our customer needs based on priorities. It's clear that 64bit is now becoming a higher priority. In VS 2005, or even SP1, it wasn't clearly a high priority, which is why we've been holding off.
As we have more committed dates, you can be sure we'll let folks know. As always, it's great to get your feedback on what you think our priorities should be, what scenarios you need support from, and when...
August 30, '07: Additional Comment
While we know developers want and need full native 64bit support, I should point out that SQLce does work in WOW mode on 64bit machines. Unfortunately because it's loaded in-proc with your app, it does mean the app must be run in WOW mode. As we ship the native version, you'll be able to simply update the SQLce install, and pop back out of WOW mode to run fully native.
August '08 Update:
64bit support has been released with SQL Server Compact SP1: SQL Server Compact 3.5 SP1 Released