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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> > 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 > >> >
