benlambt

Yes, alter the payment plan. Old users find out their subscription price has dropped -- that's a happy surprise not an annoyance. Assuming monthly billing. Yearly might be more complicated; perhaps extend the subscription length.

Why not grandfather current users in at the current price and only increase the price for new users?

If you need to drop the price back down then drop the price for all existing users too. If you're charging monthly this is easy.

With this I can consider switching back to iOS again.

Something else that provides a simple API for working with JSON in Postgres: https://github.com/robconery/massive-js (node.js)

Write a function in PLV8?

Brewing your own probiotics may be a safer option. People have been eating Sauerkraut for 1000s of years. I just add chopped cabbage and a tablespoon of salt into a quart-sized jar, fill with filtered water and wait a week or so until it tastes sour enough.