I have another thread in progress re using HBase as a financial time series database.
http://mail-archives.apache.org/mod_mbox/hadoop-hbase-user/200904.mbox/%[email protected]%3e On Fri, Apr 3, 2009 at 8:38 AM, Jim Kellerman (POWERSET) < [email protected]> wrote: > 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 > > > > > >
