Thanks for sharing your thoughts. Which HBase version are you currently using ? Have you looked at AggregateImplementation which is included in hbase jar ? A count operation (getRowNum) is in AggregateImplementation.
It would be nice if you can tell us how much difference (in terms of response time) this aggregation lags your expectation. Also take a look at HBASE-5982 HBase Coprocessor Local Aggregation Cheers On Tue, Dec 11, 2012 at 6:50 AM, nicolas maillard < [email protected]> wrote: > Hi everyone > > While working with hbase and looking at what the tables and meta look like > I > hava > thought of a couple things, maybe someone has insights. > My thoughts are around the count situation it is a current database > process to > count entries for a given query. > for example as a first check to see if everything is written or sometimes > to get > a > feel of a population. > I was wondering 2 things: > - Should'nt Hbase keep in the metrics for a table it's total entry count? > this would not take too much space and often comes in handy. Granted with a > coprocessor you could easily create a table with counters for all the other > tables in the system but it would be a nice have as a standard. > > - I was also wondering maybe every region could know the number of entries > it > contains. Every region already knows the start and endkey of it's entries. > For a > count on a given scan this would speed up the count. Every region who's > start > and > and endkey are in the scan would just send back it's population count and > only a > region that is wider then the count would need to be scanned and counted. > > Wondering if these thoughts are already implemented and if I'm missing > something > or would not be a good idea. Altenratly if this is a not a definite No for > some > reason could coprocessors allow to implement these thoughts. Can I with a > coprocessor write in the metrics part, or on a given scan first check if, > for a > region smaller than my scan, I already have written somewhere the count > instead > of > scanning and couning. > > Thnaks for any thoughts you may have > >
