Need good design pattern for caching database query result set

Question

I'm part of a team architecting a Java web application wherein users will search for results in a relational database and then view them in tabular fashion in a browser. Users will then also have the option to subsequently view the same result set (or a subset of those results) in a separate browser window, using for example a charting tool. In other words, we need to give the user the ability to visualize the same result set records later (up to a limit of 24 hours).

Since searches on the system will be resource-intensive and just out of good common sense, we would like a clean way to cache each result set so that it can be pulled later from memory (RAM or disk). We are looking for a good approach to doing this caching, we believe others have done this before, and we prefer to use a best-practice or framework rather than building such a thing from scratch. The server will have plenty of RAM but since there could be hundreds of people using the system, we may need an approach that stores to RAM first but then can also cache to hard disk if RAM is getting full.

I believe it makes most sense to persist as Java objects but I'm open to better advice. We would like a vendor-neutral approach, so that if the database team chooses to switch vendors later we aren't stuck with a proprietary solution. Thanks.

Answer 1

I think what you might be looking for is Terracotta Ehcache. This does everything you mentioned and more. It is a free product that can be used to cache things in memory, overflow to disk, specify max cache sizes by either MB or # of items, and expire based on last access time or entry time.

Answer 2

I've seen http://www.jboss.org/infinispan/ used to do exactly that. It can cache to memory, disk and or database. I wouldn't say I love it (the configuration is not super easy and documentation is somewhat lacking) but it most certainly works and is actively maintained.