deferred-query

I have frequent updates to a user table that simply sets the last seen time of a user, and I was wondering whether there is a simple way to defer them and group them into a single query after a short timeout (5 minutes or so). This would reduce queries on my user database quite a lot. If you do a UPDATE LOW_PRIORITY table ... you will make sure it will only execute your update when it's not doing anything else. Besides that I don't think there are much options inside MySQL. Also, is it causing problems now or are you simply optimizing something that isn't a problem? Personally, if I would

With the following data string[] data = { "a", "a", "b" }; I'd very much like to find duplicates and get this result: a I tried the following code var a = data.Distinct().ToList(); var b = a.Except(a).ToList(); obviously this didn't work, I can see what is happening above but I'm not sure how to fix it. When runtime is no problem, you could use var duplicates = data.Where(s => data.Count(t => t == s) > 1).Distinct().ToList(); Good old O(n^n) =) Edit: Now for a better solution. =) If you define a new extension method like static class Extensions { public static IEnumerable<T> Duplicates<T>(this