Filter and Find from in-memory data sets

Question

I have several medium-sized data sets in-memory that I need to be able to filter and find information from quickly. The data sets are small enough that I don't want to take the performance hit of going to a database every time I need an entry but large enough that I really need to index the data somehow.

Currently, I'm using POCO objects with one or more dictionaries for indexing. This works excellent when I need to find something by a specific key, but sometimes that isn't the case. As an example, I often need to find an entry within a specific date-time-range. And sometimes I need the entry with the lowest price. Most often, queries look at a few simple keys and one or two other fields at the same time.

Are there any tools, products, libraries (targeting the .NET-framework) that can help me with this? Or do I need to pick up that big dusty old Algorithms book and start looking at search-trees?

An example:

Trip

• DepartureCode
• DestinationCode
• HotelCode
• RoomCode
• Date
• Price

I need the query to be something like "get me the least expensive Trip between 2010-03-09 and 2010-03-12 where DepartureCode=LAX DestinationCode=NYC"

Answer 1

"Lowest price" and "specific date/time range" can both be handled using just a sorted collection and binary search. SortedList / SortedDictionary (or SortedSet if you're using .NET 4.0) probably do everything you need here, with only a fairly small amount of work.