We don't have that set on our cluster and aren't specifying it in our job. When I look at the different sqoop jobs I see both 3 for some and 4 for others on the jobs.
On Wed, Jun 19, 2013 at 6:50 PM, Abraham Elmahrek <[email protected]> wrote: > David, > > Well I think sqoop is looking at "mapred.map.tasks". Do you have that set > in mapred-site.xml? I thought that defaults to 2. > > -Abe > > > On Wed, Jun 19, 2013 at 4:31 PM, Abraham Elmahrek <[email protected]>wrote: > >> David, >> >> I've created https://issues.apache.org/jira/browse/SQOOP-1093 to track >> the documentation issue. Thanks for bringing this to the community's >> attention! >> >> -Abe >> >> >> On Wed, Jun 19, 2013 at 4:21 PM, Abraham Elmahrek <[email protected]>wrote: >> >>> Hey David, >>> >>> With oracle, the BigDecimalSplitter will be used by default for all >>> number types. >>> >>> -Abe >>> >>> >>> On Wed, Jun 19, 2013 at 4:05 PM, David Kincaid >>> <[email protected]>wrote: >>> >>>> 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 >>>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>> >>>> >>> >> >
