Re: hadoop results
I think I'll do the former, thanks! On Wed, Jun 29, 2011 at 11:16 PM, aaron morton wrote: > How about get_slice() with reversed == true and count = 1 to get the > highest time UUID ? > > Or you can also store a column with a magic name that have the value of the > timeuuid that is the current metric to use. > > Cheers > > - > Aaron Morton > Freelance Cassandra Developer > @aaronmorton > http://www.thelastpickle.com > > On 30 Jun 2011, at 06:35, William Oberman wrote: > > > I'll start with my question: given a CF with comparator TimeUUIDType, > what is the most efficient way to get the greatest column's value? > > > > Context: I've been running cassandra for a couple of months now, so > obviously it's time to start layering more on top :-) In my test > environment, I managed to get pig/hadoop running, and developed a few > scripts to collect metrics I've been missing since I switched from MySQL to > cassandra (including the ever useful "select count(*) from table" > equivalent). > > > > I was hoping to dump the results of this processing back into cassandra > for use in other tools/processes. My initial thought was: new CF called > "stats" with comparator TimeUUIDType. The basic idea being I'd store: > > stat_name -> time stat was computed (as UUID) -> value > > That way I can also see a historical perspective of any given stat for > auditing (and for cumulative stats to see trends). The stat_name itself is > a URI that is composed of "what" and any constraints on the "what" > (including an optional time range, if the stat supports it). E.g. > ClassOfSomething/ID/MetricName/OptionalTimeRange (or something, still > deciding on the format of the URI). But, right now, the only way I know to > get the "current" stat value would be to iterate over all columns (the > TimeUUIDs) and then return the last one. > > > > Thanks for any tips, > > > > will > > -- Will Oberman Civic Science, Inc. 3030 Penn Avenue., First Floor Pittsburgh, PA 15201 (M) 412-480-7835 (E) ober...@civicscience.com
Re: hadoop results
How about get_slice() with reversed == true and count = 1 to get the highest time UUID ? Or you can also store a column with a magic name that have the value of the timeuuid that is the current metric to use. Cheers - Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 30 Jun 2011, at 06:35, William Oberman wrote: > I'll start with my question: given a CF with comparator TimeUUIDType, what is > the most efficient way to get the greatest column's value? > > Context: I've been running cassandra for a couple of months now, so obviously > it's time to start layering more on top :-) In my test environment, I > managed to get pig/hadoop running, and developed a few scripts to collect > metrics I've been missing since I switched from MySQL to cassandra (including > the ever useful "select count(*) from table" equivalent). > > I was hoping to dump the results of this processing back into cassandra for > use in other tools/processes. My initial thought was: new CF called "stats" > with comparator TimeUUIDType. The basic idea being I'd store: > stat_name -> time stat was computed (as UUID) -> value > That way I can also see a historical perspective of any given stat for > auditing (and for cumulative stats to see trends). The stat_name itself is a > URI that is composed of "what" and any constraints on the "what" (including > an optional time range, if the stat supports it). E.g. > ClassOfSomething/ID/MetricName/OptionalTimeRange (or something, still > deciding on the format of the URI). But, right now, the only way I know to > get the "current" stat value would be to iterate over all columns (the > TimeUUIDs) and then return the last one. > > Thanks for any tips, > > will
hadoop results
I'll start with my question: given a CF with comparator TimeUUIDType, what is the most efficient way to get the greatest column's value? Context: I've been running cassandra for a couple of months now, so obviously it's time to start layering more on top :-) In my test environment, I managed to get pig/hadoop running, and developed a few scripts to collect metrics I've been missing since I switched from MySQL to cassandra (including the ever useful "select count(*) from table" equivalent). I was hoping to dump the results of this processing back into cassandra for use in other tools/processes. My initial thought was: new CF called "stats" with comparator TimeUUIDType. The basic idea being I'd store: stat_name -> time stat was computed (as UUID) -> value That way I can also see a historical perspective of any given stat for auditing (and for cumulative stats to see trends). The stat_name itself is a URI that is composed of "what" and any constraints on the "what" (including an optional time range, if the stat supports it). E.g. ClassOfSomething/ID/MetricName/OptionalTimeRange (or something, still deciding on the format of the URI). But, right now, the only way I know to get the "current" stat value would be to iterate over all columns (the TimeUUIDs) and then return the last one. Thanks for any tips, will
