Using only FMP functionality, I was importing all the historical data (about 5,700 JSON array values) from here:
I went away from the computer for an hour and only 400 or so had been imported! This is a 2019 iMac with 128 GB RAM, i9 processor, etc.
Fortunately, I can just import the historical data and then only add the daily data for each day, but it had been so long since I'd attempted anything in a FMP loop that I had forgotten what a show-stopper that approach can be.
Using FMP to import these data would take about 14 hours... I recall there are some performance workarounds, but I didn't take the time to find those again and I really don't want to have to change my workflow to accommodate FMP.
If I didn't already have the historical data, I would have to, at this point, write yet another JDBC program + Java JSON parsing and have that program stuff the data into FMP which would probably take about a minute or two (plus the time to write the code -- probably 30 mins).
If anyone is interested, I can post the CSV I converted from the JSON at the URL above.
(Spoiler alert: The same logic in Java to parse the JSON and to write all data to Maria DB takes less than 3 milliseconds)