Using functions in the graphite web-api of pmwebd

Hi everybody,

I tried using grafana (both the version that comes with the pcp rpm’s and the latest version) to create some dashboards of PCP archives. When doing this, you quite quickly run into the need to do conversions (huge pages are calculated in pages, whilst other memory components are calculated in Kb, which is how /proc/meminfo externalises this information, as an example). 

However, whenever doing so, grafana indicates there is no data to display. Upon investigating further, it turns out this is because grafana uses the graphite web-api, which, when for example a simple ‘alias()’ function is added to the request, simply does not return anything. To make sure it’s not grafana, but really the graphite interface, I used the graphite interface and did the same (added the alias() function), which gives exactly the result: no data/response.

Is this intended behaviour? Indeed http://pcp.io/man/man3/pmwebapi.3.html#lbAN <http://pcp.io/man/man3/pmwebapi.3.html#lbAN> clearly says ‘emulate a subset of the graphite web-api’, however it costed me quite some time to get to the bottom of this, mainly because of the absence of an error; a response telling it is not supported would be much more clear. 

If that is intended behaviour, it would mean doing even simple investigations is severely constrained. What would be the other options of simple (historical) investigations of pcp archives? Currently it seems I first need to import them in any of the database backends that grafana supports?

Thanks,

Frits Hoogland

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