Ask HN: Schema for Accessing ~9k data points

I am working on a freelance project that captures an audio file, runs some fourier analysis, and spits out three charts (x-y plots). Each chart has about ~3000 data points, which I plan to display with High Charts in the browser.

What database techniques do you recommend for storing and accessing this much data? Should I be storing the points in an array or in multiple rows? I'm considering Mongo too. Plan is to use Rails, so I was hoping to use a single database for both data and authentication.

I haven't dealt with queries accessing this much data for a single page, and this may very well be a tiny overall amount of data. In addition this is an MVP for demonstration to investors, so making it scalable to huge levels isn't of immediate concern.

My initial thought is that using Postgres and having one large table of data points, stored per-row, will be fine, and that that a bunch of doubles is not going to be too memory-intensive relative to images and such.

Realistically, I may just pull 100 evenly-spaced data points to make the chart, but the original data must still be stored.