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From Ted Zlatanov <...@lifelogs.com>
Subject Re: Time-series data model
Date Wed, 14 Apr 2010 13:22:42 GMT
On Wed, 14 Apr 2010 15:02:29 +0200 "Jean-Pierre Bergamin" <james@ractive.ch> wrote: 

JB> The metrics are stored together with a timestamp. The queries we want to
JB> perform are:
JB>  * The last value of a specific metric of a device
JB>  * The values of a specific metric of a device between two timestamps t1 and
JB> t2

Make your key "devicename-metricname-YYYYMMDD-HHMM" (with whatever time
sharding makes sense to you; I use UTC by-hours and by-day in my
environment).  Then your supercolumn is the collection time as a
LongType and your columns inside the supercolumn can express the metric
in detail (collector agent, detailed breakdown, etc.).

If you want your clients to discover the available metrics, you may need
to keep an external index.  But from your spec that doesn't seem necessary.

Ted


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