first of all I am a new bee by Non-SQL. I try write down my opinions as references:
If I were you, I will use 2 columnfamilys: 1.CF, key is devices 2.CF, key is timeuuid how do u think about that? Mike On Wed, Apr 14, 2010 at 3:02 PM, Jean-Pierre Bergamin <ja...@ractive.ch>wrote: > Hello everyone > > We are currently evaluating a new DB system (replacing MySQL) to store > massive amounts of time-series data. The data are various metrics from > various network and IT devices and systems. Metrics i.e. could be CPU usage > of the server "xy" in percent, memory usage of server "xy" in MB, ping > response time of server "foo" in milliseconds, network traffic of router > "bar" in MB/s and so on. Different metrics can be collected for different > devices in different intervals. > > The metrics are stored together with a timestamp. The queries we want to > perform are: > * The last value of a specific metric of a device > * The values of a specific metric of a device between two timestamps t1 > and > t2 > > I stumbled across this blog post which describes a very similar setup with > Cassandra: > https://www.cloudkick.com/blog/2010/mar/02/4_months_with_cassandra/ > This post gave me confidence that what we want is definitively doable with > Cassandra. > > But since I'm just digging into columns and super-columns and their > families, I still have some problems understanding everything. > > Our data model could look in json'isch notation like this: > { > "my_server_1": { > "cpu_usage": { > {ts: 1271248215, value: 87 }, > {ts: 1271248220, value: 34 }, > {ts: 1271248225, value: 23 }, > {ts: 1271248230, value: 49 } > } > "ping_response": { > {ts: 1271248201, value: 0.345 }, > {ts: 1271248211, value: 0.423 }, > {ts: 1271248221, value: 0.311 }, > {ts: 1271248232, value: 0.582 } > } > } > > "my_server_2": { > "cpu_usage": { > {ts: 1271248215, value: 23 }, > ... > } > "disk_usage": { > {ts: 1271243451, value: 123445 }, > ... > } > } > > "my_router_1": { > "bytes_in": { > {ts: 1271243451, value: 2452346 }, > ... > } > "bytes_out": { > {ts: 1271243451, value: 13468 }, > ... > } > "errors": { > {ts: 1271243451, value: 24 }, > ... > } > } > } > > What I don't get is how to created the two level hierarchy > [device][metric]. > > Am I right that the devices would be kept in a super column family? The > ordering of those is not important. > > But the metrics per device are also a super column, where the columns would > be the metric values ({ts: 1271243451, value: 24 }), isn't it? > > So I'd need a super column in a super column... Hm. > My brain is definitively RDBMS-damaged and I don't see through columns and > super-columns yet. :-) > > How could this be modeled in Cassandra? > > > Thank you very much > James > > >
