It does work for most devices. It seems like your device doesn't recognize the certificate installed on b4x.com.
I've actually used MySQL years ago on another project. It doesn't scale well either. Its MYISAM engine (fastest) uses table locking. It is great at bulk loading data and building indexes, but it is not good for concurrency with more than around 25 users with heavy updates. I've had MYISAM tables up to 100 million rows and it worked reasonably well for a low number of connections. Its InnoDb engine uses record locking with transactions with better concurrency, but is much slower for < 25 connections because of its greater overhead per update. I don't believe Innodb is free anymore for the community version. Since Oracle bought MySQL, they tightened up its licensing policies. I will look for another solution that has better replication methods.The bottleneck is the database. It should be simple to switch to MySQL or a different SQL engine that perform better.
Synchronizing multiple CloudKVS instances is possible but will probably be challenging to implement correctly. I don't think that it is a good approach.
I only mention this because if an application does catch on and becomes popular, the developer doesn't want to see his work come crashing down because his backend server can't handle the volume or it crashed on him. He'd be pretty embarrassed and his company's reputation would be in tatters.
I think that 25 users regarding the above statement (application does catch on and becomes popular) is not an issue. All in all just toss more RAM - move to SSD drives in your DB server.s InnoDb engine uses record locking with transactions with better concurrency, but is much slower for < 25 connections because of its greater overhead per update.
InnoDb is a CPU hog and requires at least 6 cores. If you want very good performance from InnoDb then 36 cores is ideal. More RAM will of course help, and 32GB to 62GB is recommended for a db under heavy load. Unfortunately even with all this hardware thrown at InnoDb, you're not going to get ACID transactions. You still need to turn off flushing transactions at commit using "innodb_flush_log_at_trx_commit = 0" if you want any type of speed. Turning it on will reduce the speed of InnoDb by nearly 90%. Ouch!
That is a huge OUCH! I myself was MsSQL for many years at work (and still do) and only got into MySQL when I went to b4a.flushing transactions at commit using "innodb_flush_log_at_trx_commit = 0" if you want any type of speed. Turning it on will reduce the speed of InnoDb by nearly 90%.
I don't want to get off of topic too much, but what finally turned me off of MySQL after using it for a few years, was the licensing change when Oracle took over. After talking with MySQL AB (aka Oracle) sales people about whether I could use the free community license on my own web server, he couldn't tell me for sure (or didn't want to tell me) but strongly suggested I pay for a MySQL license. At $700 (USD) per server, I decided to use only non-royalty based databases because I don't want any licensing hassles to come back and bite me. IMHO, there are better (transactional) performance (and certainly cheaper) alternatives out there like PostgreSQL, MongoDB (NOSQL) and Firebird to name a few. I believe commercial applications that use MariaDB for a database *may* still require a license depending on which libraries are included with your application. This may dissuade me from considering MariaDB (at least for commercial Windows apps that I write) and I will have to look into it further. https://mariadb.com/kb/en/mariadb/licensing-faq/