On Tue, 2010-11-02 at 09:29 -0700, Jean-Daniel Cryans wrote: > Like you said, a column is required for a row to exist, else if it > doesn't exist you don't need to delete it right? :)
Well ... of course there is some column, but not necessarily always the same one plus I don't care about its values during delete. > > What we do for fast "almost row key only" scanning is using the > FirstKeyOnlyFilter on the Scan. See the RowCounter job's code: > > Scan scan = new Scan(); > scan.setFilter(new FirstKeyOnlyFilter()); > I changed the code accordingly and as far as tests test it correctly it works. Great! > Then you can even setCaching to some high number for really fast > scanning, although deleting will still be the bottleneck. > > J-D Thanks! Henning > > On Tue, Nov 2, 2010 at 3:14 AM, Henning Blohm <[email protected]> > wrote: > > Hi, > > > > I need to delete a range of rows from an HBase table. A time-to-live > > setting as proposed in > > > > http://www.mail-archive.com/[email protected]/msg09492.html > > > > will not do as there will be no clear point in time when that clean up > > will be required / adviced. > > > > The way it is implemented now essentially looks like this: > > > > HTable c = _table(<table>); > > Scan s = new Scan("".getBytes(),endKey.getBytes()); > > s.addColumn(<family>.getBytes()); > > ResultScanner rs = c.getScanner(s); > > try { > > Result r; > > while ((r=rs.next())!=null) { > > c.delete(new Delete(r.getRow())); > > } > > } finally { > > rs.close(); > > } > > c.flushCommits(); > > > > While that works, it is suboptimal as it seems to require to define a > > column or column family > > to retrieve data for. Worse: It seems that a column is required that is > > always present to > > really hit all relevant rows. > > > > However, all that is required is the keys! > > > > I found https://issues.apache.org/jira/browse/HBASE-1481 and was > > wondering whether > > there has been any progress on that. > > > > What is the best way to accomplish something like key-only scanning? > > > > Thanks, > > Henning > >
