Hi, @david.williams: I don’t know if Alerts can do exactly what you’re looking for. The phrase, “more (or less) than it used to” could be rephrased, “deviates from the baseline”, which is exactly what baseline alert conditions are designed to detect.
To detect individual errors, you will have to use a NRQL condition (APM metric conditions can only alert on the overall error rate of the application). In order to create a baseline NRQL condition, you must create a separate condition for each error message you wish to monitor:
SELECT count(*) FROM TransactionError WHERE appName = 'My Application' AND `error.message` = 'Error 1'
SELECT count(*) FROM TransactionError WHERE appName = 'My Application' AND `error.message` = 'Error 2'
This is admittedly cumbersome, and requires you to know in advance which error messages you wish to monitor.
The alternative is to create a non-baseline NRQL condition:
SELECT count(*) FROM TransactionError WHERE appName = 'My Application' FACET `error.message`
In this case, you would specify a static threshold: you want Alerts to create an incident if any individual error message occurs more than X times per minute.
Ideally, you could use a
FACET query to create a baseline condition, but unfortunately that is not currently possible.