[Hawkular-dev] Properties store?

[John Sanda]

> On May 20, 2015, at 8:13 AM, Heiko W.Rupp <hrupp at redhat.com> wrote:
> 
> On 19 May 2015, at 15:16, John Sanda wrote:
> 
>> I agree with Lukas. At lease in RHQ, we treated most things as time 
>> series because we are interested in changes over time. Metrics is one 
>> type of time series.
> 
> Of course we are interested in changes over time.
> That does not imply storing everything as metric, as (to use that
> argument too) also did not do in RHQ.
> 
> Traits and configuration data got a very separate treatment from
> numeric metrics and also need it.
> 
> How do you aggregate traits or config objects?
> 
> How do you display traits or config objects in charts for gauge data?

I think you misunderstand what I am suggesting. Think more along the lines of a version control system. Every piece of data that gets persisted has a timestamp associated with it. In general, updating data means persisting a new copy of the data with a new timestamp. Cassandra excels at handling time series data, and again, I am not just talking about metrics. It excels because of the read/write patterns that are common with time series. In RHQ we treated most things as time series as evidence from all of the History entities. Whether it is a trait or some resource configuration, we do not want to store just the latest value, but the changes over time.