Strategies For AutoCompletion Web Services in .Net. Non UI focused

Question

I'm getting a little tired of all the UI demos of auto completion in ASP.Net. I believe the UI portion of autocompletion has been solved multiple times over again.

My question is how do you best handle the queries hitting your webservices? I'm currently implementing an autocompletion service for a musician database. The database is fairly small with only 20,000 rows, but autocompletion is extremely speed sensitive. It needs to be fairly instant to be of any use.

I'm currently using NHibernate for my DAL, but I'm wondering if this is a place where I may want to bypass NHibernate. Perhaps projections on named queries would be the best strategy? Where do I cache? NHibernate's 2nd level cache? Let the web service cache?

I've already thought of a lot of naive methods to develop this, but I would like to soak in any tips that people already have in the wild. Also, what if you have many different types of entities you want autocompletion on? Do you spread those implementations around in their different repositories or do you design/implement a completely separate autocompletion service?

Answer 1

This depends on how large your sites traffic is. I generally suggest using a product such as MemCached or MemCached Win32 depending on your environment availability (MemCached for cheap linux boxes if you can is best...all that is needed is a ton of memory!). You might also look to something like Velocity (MS's new cache cloud offering). This would then allow you to cache a key (what ever the query is) with the results efficiently! Keep your cache times down based on however frequently you are updating your dataset. If you don't update often then the cache time can be longer. If you find that your cache cloud is growing like crazy you might want to only cache what is most frequently asked for (though your cache implementation should handle this by removing what is not accessed frequently!).