As long as the amount of data you have to store is less than about 256 bytes per second, and you have the ability to run node.js on a computer somewhere, it could be a regular Windows, Mac, or Linux computer, or even a Raspberry Pi, you can easily do this. Here’s a quick sample I wrote that shows how to store data generated by Particle.publish on the Photon/Electron in a MySQL database using node.js.