Hey Scott, Patrick's answer is spot on. I'm curious, though, is your usecase to find the latest value? Effectively a 'SORT BY DESC date LIMIT 1', or are you looking for the last n values, or all values? I ask because we frequently get the 'last value' question, and the solution for that might be more specific (and simpler) than a generalized reverse sort + limit.
- Dan On Mon, Apr 23, 2018 at 1:25 PM, Patrick Angeles <[email protected]> wrote: > The common technique is to use (MAX_LONG - timestamp). Unfortunately this > won't let you toggle the sort order back-and-forth on the same table. You > could have a duplicate table with the inverse key, effectively using it as > a secondary index. > > As of version 0.98, HBase supports a reverse scan without a 'secondary > index' table (HBASE-4811), so with a bit of work Kudu may be able to > provide something similar. > > > Patrick Angeles > Chief Architect Financial Services > 151 West 26th Street Suite 1002 | > <https://maps.google.com/?q=151+West+26th+Street+Suite+1002+%7C%C2%A0+New+York,+NY+10001&entry=gmail&source=g>New > York, NY 10001 > <https://maps.google.com/?q=151+West+26th+Street+Suite+1002+%7C%C2%A0+New+York,+NY+10001&entry=gmail&source=g> > +1 (917) 633-4524 > > On Sat, Apr 21, 2018 at 10:36 PM, Scott Reynolds <[email protected]> > wrote: > >> Today we are using Kudu to store timeseries information and would like >> the ability to toggle the sort direction. It is unclear to me at the moment >> how to achieve this efficiently. I naively assumed Kudu could read the >> primary key in reverse but there doesn't appear to be the case ATM. >> >> If you were tasked with implementing a reverse sort on the primary key >> (Date Desc) how would you go about implementing it ? >> >> Thanks! >> > >
