I was going to say something similar. But as soon as you have a major compaction you endup with a single file and everything into it. So depending on your key distribution you might still read everything. If you read just the last few minutes over a huge table, then yes, skip will help. Else, I'm not sure it will hep that much :(
2015-02-28 18:25 GMT-05:00 Nick Dimiduk <[email protected]>: > A Scan without start and end rows will be issued to all regions in the > table -- a full table scan. Within each region, store files will be > selected to participate in the scan based on on the min/max timestamps > from their > headers. > > On Saturday, February 28, 2015, Kristoffer Sjögren <[email protected]> > wrote: > > > If Scan.setTimeRange is a full table scan then it runs surprisingly fast > on > > tables that host a few hundred million rows :-) > > > > > > > > On Sat, Feb 28, 2015 at 8:05 PM, Kristoffer Sjögren <[email protected] > > <javascript:;>> > > wrote: > > > > > Hi Jean-Marc > > > > > > I was thinking of Scan.setTimeRange to only get the x latest rows, but > I > > > would like to avoid a full table scan. > > > > > > The alternative would be to use set the timestamp in the key and use > > start > > > and stop key. But since HBase already is aware of timestamps I tought > it > > > might optimize Scan.setTimeRange scans? > > > > > > Cheers, > > > -Kristoffer > > > > > > On Sat, Feb 28, 2015 at 7:45 PM, Jean-Marc Spaggiari < > > > [email protected] <javascript:;>> wrote: > > > > > >> Hi Kristoffer, > > >> > > >> What do you mean by "timerange scans"? If you want to scan everything > > from > > >> your table, you will always end up with a full table scan, no? > > >> > > >> JM > > >> > > >> 2015-02-28 13:41 GMT-05:00 Kristoffer Sjögren <[email protected] > > <javascript:;>>: > > >> > > >> > Hi > > >> > > > >> > I want to understand the effectiveness of timerange scans without > > >> setting > > >> > start and stop keys? Will HBase do a full table scan or will the > scan > > be > > >> > optimized in any way? > > >> > > > >> > Cheers, > > >> > -Kristoffer > > >> > > > >> > > > > > > > > >
