Abe, the database is Oracle.
On Wed, Jun 19, 2013 at 5:48 PM, Abraham Elmahrek <[email protected]> wrote: > David, > > What database are you importing from? The description I gave was for > datatypes that map to the BigDecimal Splitter. The userguide might be > referring to the IntegerSplitter which will add the remainder to the last > value. > > -Abe > > > On Wed, Jun 19, 2013 at 1:23 PM, David Kincaid <[email protected]>wrote: > >> Thanks. We didn't specify the number of mappers, so it's giving us 4. I >> understand your explanation, but it seems to conflict with the Sqoop user >> guide ( >> http://sqoop.apache.org/docs/1.4.3/SqoopUserGuide.html#_controlling_parallelism >> ): >> >> "When performing parallel imports, Sqoop needs a criterion by which it >> can split the workload. Sqoop uses a *splitting column* to split the >> workload. By default, Sqoop will identify the primary key column (if >> present) in a table and use it as the splitting column. The low and high >> values for the splitting column are retrieved from the database, and the >> map tasks operate on evenly-sized components of the total range. For >> example, if you had a table with a primary key column of id whose >> minimum value was 0 and maximum value was 1000, and Sqoop was directed to >> use 4 tasks, Sqoop would run four processes which each execute SQL >> statements of the form SELECT * FROM sometable WHERE id >= lo AND id < hi, >> with (lo, hi) set to (0, 250), (250, 500), (500, 750), and (750, 1001) >> in the different tasks." >> >> >> On Wed, Jun 19, 2013 at 3:14 PM, Abraham Elmahrek <[email protected]>wrote: >> >>> Hey David, >>> >>> Here's the algorithm: >>> Split lengths are defined by (max - min)/(# mappers) and whatever is >>> left is tacked on at the end. So in this case, (288272191-2110)/3 = >>> 96090027.33... So I'm assuming the .33... is rounded down and split lengths >>> will be of length 96090027. Sqoop will then create splits with the >>> following points: (min) + (range length)*(n). We can see that 2110 + >>> 96090027*0 >>> = 2110, 2110 + 96090027*1 = 96092137, 2110 + 96090027*2 = 192182164, >>> and 2110 + 96090027*3 = 288272191 will be generated based off of this >>> algorithm. The last point to be added will be 288272192 because the max >>> value is not part of the generated split points. Then sqoop will >>> distributed accordingly based off of these points as you've pointed out >>> above. >>> >>> Just to be sure, did you configure sqoop to use 3 mappers? >>> >>> Hope this helps, >>> -Abe >>> >>> >>> On Wed, Jun 19, 2013 at 8:33 AM, David Kincaid >>> <[email protected]>wrote: >>> >>>> We're seeing a strange thing happen with a sqoop import job with the >>>> way the key range is getting distributed among the 4 mappers that are >>>> running. The minimum key value is 2110 and the maximum value is 288272191. >>>> We are getting one mapper that is only getting one record to import. Here >>>> is the distribution among the mappers: >>>> >>>> [2110, 96092137) >>>> [96092137, 192182164) >>>> [192182164, 288272191) >>>> [288272191, 288272192) >>>> >>>> you can see that the fourth mapper is given a range with only one value >>>> in it. Could someone help me understand what is going on? >>>> >>>> Thanks, >>>> >>>> Dave >>>> >>> >>> >> >
