Itemupdating called twice datinging
Column that allows full-blown Ext JS 4 components to be returned from the renderer function.
I know a lot of people have written custom code to do this sort of thing but as far as I'm aware no-one has ever wrapped it up in a reusable class.
The queries to render this graph now complete in 1-6 seconds (depending on SSD cache / age of data), or about 0.5 - 1s uncached per item in graph over a large span.
I am unsure when it happens, however I have observed (at rate of ~10/day on our current test server) errors like "Duplicate entry '42120-1452240997' for key 'PRIMARY' [insert into history_uint ..." Given that the most frequent item is 1 per second this is obviously non-sensense, but regardless the correct behaviour would be to ignore the duplicate entry and insert the rest.
When the code gets to the db Collections has now 3 items with the last two being exactly the same (similarly in variable existing).