[Hawkular-dev] Calculated metrics: sharing ideas

[John Mazzitelli]

Take a look at the query language of Prometheus:

https://prometheus.io/docs/querying/basics/

----- Original Message -----
> Hi,
> 
> I just want to share some ideas about the eventuality of having a language to
> perform some arithmetic / aggregations on metrics, before it goes out of my
> head...
> 
> Here's an example of what I would personally love to see in Hawkular:
> 
> ----------------------------------------------
> Example:
> sum(stats(rate((id(my_metric), tags(a=foo AND b=bar), regexp(something_.+)),
> 5m), 10m))
> | 
> |=> "id", "tags" and "regexp" all return a set of raw metrics (0-1 for id,
> |0-n for tags and regexp)
> |==> "(a,b,c)" takes n parameters, all sets of metrics, and flatten them in a
> |single set
> |===> rate(set_of_raw_metrics, rate_period) computes the rate for each of
> |them and return a set of metrics (map n=>n)
> |====> stats(set_of_raw_metrics, bucket_size) bucketize the raw metrics,
> |returning the same number of bucketized metrics (map n=>n)
> |=====> sum(set_of_stats_metrics) sums every buckets, returning a single
> |bucketized metric (fold n=>1)
> 
> 
> Other:
> Functions like "sum" that take stats_metrics could have overloaded shortcut
> "sum(set_of_raw_metrics, bucket_size)" to perform the bucketing.
> In other words above example could be rewritten:
> sum(rate((id(my_metric), tags(a=foo AND b=bar), regexp(something_.+)), 5m),
> 10m)
> 
> Note: we can do aggregations like "sum" on raw data if necessary, it just
> means we have to interpolate.
> 
> Scalar operations:
> sum((id(a_metric_in_milliseconds), 1000* id(a_metric_in_seconds)), 10m)
> ----------------------------------------------
> 
> Of course many other functions could come growing the library.
> 
> Now I suppose the big question, if we want to do such thing, is "are we going
> to invent our own language?" I don't know if there are standards for this,
> and if they are good.
> 
> The Prometheus query language cannot be transposed because a label is not a
> tag and it makes no sense for us to write something like
> "my_metric{tag=foo}", it's either "my_metric" or "tag=foo".
> 
> The same language could be used both for read-time on-the-fly aggregations
> and write-time / cron-based rollups.
> 
> WDYT?
> 
> 
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