My app is growing very fast, and we have used Parse.com as the main database.
We want to create a web version of this to work together with the app for iOS and Android.
The only limitation that we know from Parse.com is that the queries max limit is 1000, so after it you need to create a function to do more queries.
So talking about a very large database, performance on server-side, Users doing queries using 3g network and scalability, is a good way move it to mysql?
In terms of scalability I guess you really need to worry about that if you are managing your own servers. Worse case, you go with a professional hosting service but use VPS.
Parse uses mongoDB which is entirely different than MySQL. The 1000 limit should really be an issue regardless of what database you use because you should be structuring your app that you don't grab anywhere near 1000 items at once. That is where lazy loading comes into play.
Parse is a
REST API. This means you're using HTTP requests to get information. You will need to write an API or find an open source option to put on your server. You need to make sure that your code runs efficiently so you can get results fast and put as little strain as possible on your servers.
Another thing is to try and prevent having 1000 queries. If there's a way where you can download data that can be reused in the app instead of re-downloading it each time then do it. Less strain on servers, quick response, and little data going back and forth.
That's really all I have to offer.