Hi Ning, For the dataset I'm experimenting with, the total size of the output is 2mb, and the files are at most a few kb in size. My hive.input.format was set to default HiveInputFormat; however, when I set it to CombineHiveInputFormat, it only made the first stage of the job use fewer mappers. The merge job was *still* filtered out at runtime. I also tried set hive.mergejob.maponly=false; that didn't have any effect.
I am a bit at a loss what to do here. Is there a way to see what's going on exactly using e.g. debug log levels?.. Btw, I'm also using dynamic partitions; could that somehow be interfering with the merge job?.. I'm running a relatively fresh Hive from trunk (built maybe a month ago). --Leo On Thu, Nov 18, 2010 at 1:12 PM, Ning Zhang <nzh...@fb.com> wrote: > The settings looks good. The parameter hive.merge.size.smallfiles.avgsize is > used to determine at run time if a merge should be triggered: if the average > size of the files in the partition is SMALLER than the parameter and there > are more than 1 file, the merge should be scheduled. Can you try to see if > you have any big files as well in your resulting partition? If it is because > of a very large file, you can set the parameter large enough. > > Another possibility is that your Hadoop installation does not support > CombineHiveInputFormat, which is used for the new merge job. Someone reported > previously merge was not successful because of this. If that's the case, you > can turn off CombineHiveInputFormat and use the old HiveInputFormat (though > slower) by setting hive.mergejob.maponly=false. > > Ning > On Nov 17, 2010, at 6:00 PM, Leo Alekseyev wrote: > >> I have jobs that sample (or generate) a small amount of data from a >> large table. At the end, I get e.g. about 3000 or more files of 1kb >> or so. This becomes a nuisance. How can I make Hive do another pass >> to merge the output? I have the following settings: >> >> hive.merge.mapfiles=true >> hive.merge.mapredfiles=true >> hive.merge.size.per.task=256000000 >> hive.merge.size.smallfiles.avgsize=16000000 >> >> After setting hive.merge* to true, Hive started indicating "Total >> MapReduce jobs = 2". However, after generating the >> lots-of-small-files table, Hive says: >> Ended Job = job_201011021934_1344 >> Ended Job = 781771542, job is filtered out (removed at runtime). >> >> Is there a way to force the merge, or am I missing something? >> --Leo > >
