[Hawkular-dev] Bucketed data issues when no datapoints fall in the bucket span.

[Matt Wringe]

On 08/09/15 04:56 PM, Thomas Segismont wrote:
> It's hard to determine what it means to interpolate values when you're
> looking at a metric at its resolution level.
>
> Put another way, what does it mean to ask for avg/min/median for every
> 30 seconds timespan if you have a point every 30 seconds?

Yeah, that is essentially the problem. Bucketed data is not all the 
useful once you start to get into a smaller number of data points per 
bucket.

But then it comes into the situation when something is expecting 
bucketed data and we don't have metric points for the level it is 
requesting (eg charting).

So how do you solve the chart "zooming in" situation? We could just 
return the actual data points in that situation and not bucketed data, 
but since its a different format and it gets tricky for clients to use it.

>
> Le 08/09/2015 22:30, Matt Wringe a écrit :
>> I am running into a few issues when dealing with bucketed data when
>> there is no datapoints which happen to fall within a particular bucket size.
>>
>> For instance, lets say I am getting data every 30 seconds. If my bucket
>> spans at least 30 seconds than everything works fine and all my buckets
>> contain non-empty data.
>>
>> But, if I were to 'zoom in' a bit and ask for a bucket span less than 30
>> seconds, then some of the buckets would return with empty data.
>>
>> Or, if my data does not come in perfectly for each of those 30 second
>> fragments (say the timestamps are plus or minus a couple of seconds)
>> then I could also end up with some buckets containing empty data as well.
>>
>> This causes some strange charting behaviour. If a bucket is empty, then
>> its just not displayed in the chart. This means we can end up with
>> non-continuous lines in the charts, which is not desired.
>>
>> Anyone know what should be done in this situation?
>>
>> Its not really that there is no data there and nothing should be
>> graphed, its just that the bucket span is too small to show anything in
>> there.
>>
>> Should charting just ignore empty buckets if they are not at the start
>> or the end?
>>
>> Should hawkular metrics perform calculations to figure out what the
>> missing bucket values should be?
>>
>> Any ideas here?
>>
>>
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