Which database is good to store (metagenomic) relative abundance data?

The simple question is: how to store relative abundance data in a database? Which database to choose?

I am talking here about metagenomics data, relative abundance of species or some features. Each feature has single abundance value. For each sample, there are 100’s to 1000′ features, and the number of unique features between samples keeps growing fast with new samples. Target number of samples ranging 1000-10000.

The most lame way of handling that would be some big array (e.g. sampleID x featureID) but that would not be very convenient, as it will be holding mostly zeros (for features not found in given sample).
I wanted to organize it into some database, but Which one will be effective to store and query this kind of data? Until now I was working only with relational data bases (MySQL), but I guess that is not the solution here (growing number of samples and unique features). Or is it?

Thanks for suggestions!