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 > >> > > >> > > > > >
