There are a number of Jiras open to address this issue. See HBASE-33, HBASE-52 and HBASE-1182
--- Jim Kellerman, Powerset (Live Search, Microsoft Corporation) > -----Original Message----- > From: Genady [mailto:[email protected]] > Sent: Friday, April 03, 2009 2:56 AM > To: [email protected] > Subject: RE: timestamp uses > > Jonathan, > > Please correct me If I wrong, but one of the features that HBase obviously > missing is possibility to select records based on timestamp range(week, > month, etc.), as far as understand, it's possible to make select with > specified timestamps, but in a most cases you want to select ranges. To > solve it there is always option to put time/date as row key, but in most > designs you can't do it. > > Thanks, > Gennady > > > -----Original Message----- > From: Jonathan Gray [mailto:[email protected]] > Sent: Wednesday, April 01, 2009 7:55 PM > To: [email protected] > Subject: RE: timestamp uses > > Wes, > > The timestamp is used for versioning. > > There have been arguments recently around 0.20 changes regarding whether > the > user should be allowed to manually set this stamp or it is always > generated > server-side according to NOW. > > Currently the decision has been made to allow the user to manually set the > stamp on insertion, to any stamp at or before now (but not in the future). > This is so we can ensure when doing a flush that no entries in the > storefile > will have a stamp that is later than the flush stamp. > > In the canonical use case for HBase, web crawling, timestamps are used to > version and date each crawl. You could then set HBase to keep the 10 most > recent versions and older ones would be deleted on major compactions. > > At the other extreme, you could set the timestamp then each individual > column in a family could be a time-ordered list of whatever you want. In > practice, however, I've found that it makes more sense to encode stamps in > your row keys or column names. > > Hope that helps. > > JG > > > -----Original Message----- > > From: Wes Chow [mailto:[email protected]] > > Sent: Wednesday, April 01, 2009 5:56 AM > > To: [email protected] > > Subject: timestamp uses > > > > > > So far, few if any of the schema designs I've come across have really > > talked about using the timestamp field and HBase's automatic deletion > > of > > old cells in a smart way. > > > > What is the timestamp typically used for? Snapshotting? Implementing > > more complicated transactions than HBase natively supports? > > > > > > Wes > >
