I once read about a database for rolling logs. It was for keeping server data over a fixed period and basically it worked like a huge circular buffer on disk. Since all the space was statically allocated, it didn't suffer from problems of purging old records and the like.
I tried to find the name of that setup today and just can't seem to locate it. I'm recording server log messages (IP traffic mostly) and I only want to keep the data for a set # of days, and just let the wrap around and overwrite the old data, but I still want to be able to mine that data.
Does anyone else remember hearing about it or what the name of it was? I do know it was open source and had been out several years, so its probably at least 3-5 years old.
Was it RRDTool?
You can use MongoDB with capped collections. Works perfectly for logs.