Is there a quick/reliable way to downsample a PHPFINA dataset?
I’ve been monitoring temperatures in various parts of the house with 4x EmonTH’s, at 1 min intervals.
With hindsight that may have been a little OTT. Now that I’m planning on replacing them with Xiaomi Mijia BLE Sensors (LYWSD03MMC) via an OpenMQTTGateway so that I can have more sensors and recycle the EmonTH’s into more useful duties, I’d like to move the intervals to 5mins to help with battery life and shrink the data.
However, I’d like to keep the existing data too (7years worth), and add the new data to the old.
I realise I can feed the data slower, but that’ll waste space.
So, is there a way to pump the old feed into a new one keeping the correct dates but only every fifth datapoint?