Downsampling time series

[creyer s]

Cassandra is a great fit for time series. I have a project where I need to draw graphs for the values stored in Cassandra. Based on the 5 zoom rates on the graph, I need to perform downsampling. I would prefer to have the ability to define a custom downsampling function, but an avg might work as well. Is there a way to perform the downsampling in Cassandra in an automated way without being required to write that software myself?

Thanks

[Rick Bullotta]

Cassandra doesn’t do aggregates in a traditional way.  Some apps pre-calculate aggregates as part of the write/ingest process.  You could also use Hadoop (and related stuff) on top of Cassandra to do background and on-demand aggregates, such as with DataStax Enterprise.  Also, a piece of advice: arithmetic averages are not a good idea for time series data unless you are certain that the data is collected at fixed intervals, and even then, reliably.  It is usually more meaningful to do time-weighted average of each value/interval.

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[creyer s]

Thank you for your reply. Indeed avg is not a good function, but I was just making a point. I am currently analyzing different solutions for my problem which involves Druid and Geras.