On Mon, Apr 22, 2013 at 8:59 PM, Venkat <[email protected]> wrote: > It looks like versioningiterator gives me the past versions for a cell > .... but I need to look across rows .. > > I am inserting time series data for set of machines into accumulo and i am > using a combo of machineid + timestamp as the row ID and metric as the cq. > So for me to get the last time a metric has been inserted for an asset, i > need to look across row IDs and get the last 5 rows that got inserted with > that metric ... >
You could consider sorting your data such that the most recent timestamps come first. If you insert (machineid + (999999999999 - timestamp)). To get the 5 most recent row, start scanning at (machineid + 999999999999) and stop when you have 5 rows. I picked a completely arbitrary number of 9's for the example, not sure what time resolution its appropriate for. > > > > On Mon, Apr 22, 2013 at 2:48 PM, Billie Rinaldi > <[email protected]>wrote: > >> You could use a VersioningIterator with maxVersions set to 5. >> >> Billie >> >> >> >> On Mon, Apr 22, 2013 at 11:29 AM, Venkat <[email protected]> wrote: >> >>> hello accumulo, >>> >>> what is a good way to get rows in chronological order ? i am trying to >>> get to a use case of "give me the last 5 inserted for this particular cf, >>> cq ..." timestampfilter works well when I know the times but i dont know >>> the exact times of insertion. >>> >> >> >
