Thanks for sharing the information below. How do you plan to store time (when the bus gets to each stop) in the row ? Or maybe it is not of importance to you ?
On Sat, Apr 20, 2013 at 2:24 PM, Pal Konyves <paul.kony...@gmail.com> wrote: > I am making a paper for school about HBase, so the data I chose is not a > real usable example. I am familiar with GTFS that is a de facto standard > for storing information about public transportation schedules: when vehicle > arrives to a stop and where it goes toward. > > I chose to genrate the rows on the fly, where each row represents a > sequence of 'bus' stops that make a route from the first stop until the > last stop. > e.g.: [first_stop_id,last_stop_id],string_sequence_of_stops > where within the [...] is the rowkey. > > So long story short, I generate the data. I want to use the HBase java > client api to store the rows with Put. I plan to randomize it by picking > random first_stop_id-s, and use more threads. > > the rowkeys will still have a sequence, because the way I generate the rows > will output about 100-1000 rows starting with the same first_stop_id within > the rowkey. The total ammount of rows will be about billions, and would > take up about 1TB. > > > On Sat, Apr 20, 2013 at 10:54 PM, Ted Yu <yuzhih...@gmail.com> wrote: > > > The answer to your first question is yes - midkey of the key range would > > be chosen as split key. > > > > For #2, can you tell us how you plan to randomize the loading ? > > Bulk load normally means preparing HFiles which would be loaded directly > > into your table. > > > > Cheers > > > > On Apr 20, 2013, at 1:11 PM, Pal Konyves <paul.kony...@gmail.com> wrote: > > > > > Hi Ted, > > > Only one family, my data is very simple key-value, although I want to > > make > > > sequential scan, so making a hash of the key is not an option. > > > > > > > > > > > > On Sat, Apr 20, 2013 at 10:07 PM, Ted Yu <yuzhih...@gmail.com> wrote: > > > > > >> How many column families do you have ? > > >> > > >> For #3, per-splitting table at the row keys corresponding to peaks > makes > > >> sense. > > >> > > >> On Apr 20, 2013, at 10:52 AM, Pal Konyves <paul.kony...@gmail.com> > > wrote: > > >> > > >>> Hi, > > >>> > > >>> I am just reading about region splitting. By default - as I > understand > > - > > >>> Hbase handles splitting the regions. I just don't know how to imagine > > on > > >>> which key it splits the regions. > > >>> > > >>> 1) For example when I write MD5 hash of rowkeys, they are most > probably > > >>> evenly distributed from > > >>> 000000... to FFFFF... right? When Hbase starts with one region, all > > the > > >>> writes goes into that region, and when the HFile get's too big, it > just > > >>> gets for example the median value of the stored keys, and split the > > >> region > > >>> by this? > > >>> > > >>> 2) I want to bulk load tons of data with the HBase java client API > put > > >>> operations. I want it to perform well. My keys are numeric sequential > > >>> values (which I know from this post, I cannot load into Hbase > > >> sequentially, > > >>> because the Hbase tables are going to be sad > > >> > > > http://ikaisays.com/2011/01/25/app-engine-datastore-tip-monotonically-increasing-values-are-bad/ > > >>> ) > > >>> So I thought I would pre-split the table into regions, and load the > > data > > >>> randomized. This way I will get good distribution among region > servers > > in > > >>> terms of network IO from the beginning. Is that a good idea? > > >>> > > >>> 3) If my rowkeys are not evenly distributed in the keyspace, but they > > >> show > > >>> some peaks or bursts. e.g. 000-999, but most of the keys gather > around > > >> 020 > > >>> and 060 values, is it a good idea to have the pre region splits at > > those > > >>> peaks? > > >>> > > >>> Thanks in advance, > > >>> Pal > > >> > > >
