Great, Thanks! On Thu, Oct 22, 2009 at 2:46 PM, Paul Davis <[email protected]>wrote:
> > 1. What exactly is 'current' & 'count'. What are each of them recording > > and why is 'count' less than 'current' in my system (seems counter > intuitive > > to me). > > Current is a sum of the values recorded. For things like HTTP > requests, this is the total number of requsts. > > Count is the number of updates for this metric in the given time span. > > Stats works with two parts, a collector and an aggregator. The > collector part receives messages from through out CouchDB and holds > that data in a table. Once a second the aggregator will sweep through > the collector and update its stats. > > So, if you had 20K requests between to aggregator sweeps, Current > would be incremented by 20K and Count is incremented by 1. > > > 2. Can the 'mean' here be interpreted as average reads per second? > > For requests, the mean is roughly the requests per second. Its not as > theoretically correct as something like RRDtool because we don't > interpolate, we just average the reads we take roughly once a second. > > > 3. Is there any indication of exactly where within the 5 minute > interval > > we are? > > > > No, but the current implementation (committed after 0.10.x was > branched) does not reset statistic aggregators as the old code did. > The new method is the more standard "these stats reflect all values > seen in the last 5 minutes" regardless of when you query it. > > > Another metric that I'm having trouble with is the 'request_time'. > Querying > > it returns data similar to: > > [snip] > > > 1. Again, same question about exactly what the 'count' and 'current' > > values mean for this metric. > > Oh weird. So, Count has the same meaning as before, but here Current > is the length of the last recorded request. The weirdness comes from > the fact that this is averaging a set of distinct points, where as > things like requests are averaging the relative change so current > makes a bit more sense there. > > > 2. Does the 'mean' represent the average time for a request in CouchDB > in > > seconds? > > milliseconds. > > HTH, > Paul Davis >
