Key/value store for random data sampling

For the moment to generate random data for testing I stream my data, then I shuffle the stream and take the first n elements. But I was thinking about storing the data in a local lightweight key/value store. Is there one that allows to shuffle the key in the cache or at a low level? Is there another way to do this? My goal is to have a low level function that generates random samples in a fairly unbiased manner without taking too much memory.