As it is a 50 Gb single file, I believe this job need more than one mapper.
I do not find any mapred.max.split.size parameter in the job configuration xml file (only mapred.min.split.size = 0). Is there any "key word" to activate parallelism into the pig script ? Jérôme. Le Tue, 5 Feb 2013 14:13:32 -0800, Cheolsoo Park <[email protected]> a écrit : > >> But one more point, I have only one mapper running with this pig > >> job as > my cluster has 4 slaves. How could it be different ? > > Are you asking why only a single mapper runs even though there are 3 > more slaves available? 4 slaves doesn't mean that you will always > have 4 mappers/reducers. Hadoop launches a mapper per file split. > > How many input file do you have? > > - If you have just one small file, Pig will launch a single mapper. > You can increase parallelism by splitting that file into smaller > splits: > http://stackoverflow.com/questions/9678180/change-file-split-size-in-hadoop > > - If you have many small files, Pig will combine them into a single > split and launch a single mapper. This case, you might want to change > pig.maxCombinedSplitSize: > http://pig.apache.org/docs/r0.10.0/perf.html#combine-files > > Thanks, > Cheolsoo > > On Tue, Feb 5, 2013 at 8:06 AM, Jerome Pierson > <[email protected]>wrote: > > > Thaks a lot. It works fine. > > > > But one more point, I have only one mapper running with this pig > > job as my cluster has 4 slaves. > > How could it be different ? > > > > Regards, > > Jérôme > > > > > > Le 31/01/2013 20:45, Cheolsoo Park a écrit : > > > >> Hi Jerome, > >> > >> Try this: > >> > >> XmlTag = FOREACH xmlToTuple GENERATE FLATTEN ($0); > >> XmlTag2 = FOREACH XmlTag { > >> tag_with_amenity = FILTER tag BY (tag_attr_k == 'amenity'); > >> GENERATE *, COUNT(tag_with_amenity) AS count; > >> }; > >> XmlTag3 = FOREACH (FILTER XmlTag2 BY count > 0) GENERATE > >> node_attr_id, node_attr_lon, node_attr_lat, tag; > >> > >> Thanks, > >> Cheolsoo > >> > >> > >> On Thu, Jan 31, 2013 at 9:19 AM, Jerome Pierson > >> <[email protected]>**wrote: > >> > >> Hi There, > >>> > >>> I am a beginner, I achieved something, but I guess I could have > >>> done better. Let me explain. > >>> (Pig 0.10) > >>> > >>> My data is DESCRIBE as : > >>> > >>> xmlToTuple: {(node_attr_id: int,node_attr_lon: > >>> chararray,node_attr_lat: chararray,tag: {(tag_attr_k: > >>> chararray,tag_attr_v: chararray)})} > >>> > >>> > >>> and DUMP like this : > >>> > >>> ((100312088,45.2745669,-12.****7776222,{(created_by,JOSM)})) > >>> ((100948454,45.2620946,-12.****7849171,)) > >>> ((100948519,45.2356985,-12.****7707014,{(created_by,JOSM)})) > >>> ((704398904,45.2416667,-13.****0058333,{(lat,-13.00583333),(**** > >>> lon,45.24166667)})) > >>> ((1230941976,45.0743117,-12.****6888807,{(place,village)})) > >>> ((1230941977,45.0832807,-12.****6810328,{(name,Mtsahara)})) > >>> ((1976927219,45.2272263,-12.****7794359,)) > >>> ((1751057677,45.2216163,-12.****7825896,{(amenity,fast_food),(**** > >>> name,Brochetterie)})) > >>> ((1751057678,45.2216953,-12.****7829678,{(amenity,fast_food),(**** > >>> name,Brochetterie)})) > >>> ((100948360,45.2338541,-12.****7762230,{(amenity,ferry_****terminal)})) > >>> ((362795028,45.2086809,-12.****8062991,{(amenity,fuel),(**** > >>> operator,Total)})) > >>> > >>> > >>> I want to extract the record which have a certain value for the > >>> tag_attr_k > >>> field. For example, give me the record where there is a > >>> tag_attr_k = amesity ? That should be : > >>> > >>> (100948360,-12.7762230,45.****2338541,{(amenity,ferry_****terminal)}) > >>> (362795028,-12.8062991,45.****2086809,{(operator,Total),(**** > >>> amenity,fuel)}) > >>> (1751057677,-12.7825896,45.****2216163,{(amenity,fast_food),(**** > >>> name,Brochetterie)}) > >>> (1751057678,-12.7829678,45.****2216953,{(amenity,fast_food),(**** > >>> name,Brochetterie)}) > >>> > >>> So (node_attr_id, node_attr_lat , node_attr_lon,{(tag_attr_k, > >>> tag_attr_v)...(tag_attr_k,tag_****attr_v)} > >>> > >>> > >>> I ended up with this script. > >>> > >>> > >>> ... > >>> XmlTag = foreach xmlToTuple GENERATE FLATTEN ($0); --removed top > >>> including > >>> level bag > >>> XmlTag2 = foreach XmlTag GENERATE $0 as id, $1 as lon, $2 as lat, > >>> FLATTEN (tag) as (key, value); --flatten the bag of tags > >>> XmlTag3 = FILTER XmlTag2 BY key == 'amenity'; -- get all the > >>> records with > >>> amenity tags > >>> XmlTag4 = JOIN XmlTag3 BY id, XmlTag2 BY id; -- re-build records > >>> with all tags containing amenity tag > >>> XmlTag7 = foreach XmlTag4 GENERATE $0 as id,$1 as lon, $2 as > >>> lat,$8 as key, $9 as value; -- re-build records : removing > >>> redundant field XmlTag5 = GROUP XmlTag7 BY (id,lat,lon); -- > >>> re-build records : grouping redundant records > >>> XmlTag8 = foreach XmlTag5 { --rebuild records : id,lat,long > >>> {(key,value)...(key,value)} > >>> tag = foreach XmlTag7 GENERATE key, value; > >>> GENERATE group.id,group.lat,group.lon,****tag; > >>> > >>> }; > >>> > >>> Using this variable: > >>> > >>> xmlToTuple: {(node_attr_id: int,node_attr_lon: > >>> chararray,node_attr_lat: chararray,tag: {(tag_attr_k: > >>> chararray,tag_attr_v: chararray)})} XmlTag: {null::node_attr_id: > >>> int,null::node_attr_lon: chararray,null::node_attr_lat: > >>> chararray,null::tag: {(tag_attr_k: chararray,tag_attr_v: > >>> chararray)}} XmlTag2: {id: int,lon: chararray,lat: chararray,key: > >>> chararray,value: chararray} > >>> XmlTag3: {id: int,lon: chararray,lat: chararray,key: > >>> chararray,value: chararray} > >>> XmlTag4: {XmlTag3::id: int,XmlTag3::lon: chararray,XmlTag3::lat: > >>> chararray,XmlTag3::key: chararray,XmlTag3::value: > >>> chararray,XmlTag2::id: int,XmlTag2::lon: chararray,XmlTag2::lat: > >>> chararray,XmlTag2::key: chararray,XmlTag2::value: chararray} > >>> XmlTag7: {id: int,lon: chararray,lat: chararray,key: > >>> chararray,value: chararray} > >>> XmlTag5: {group: (id: int,lat: chararray,lon: chararray),XmlTag7: > >>> {(id: int,lon: chararray,lat: chararray,key: chararray,value: > >>> chararray)}} XmlTag8: {id: int,lat: chararray,lon: chararray,tag: > >>> {(key: chararray,value: chararray)}} > >>> > >>> > >>> I guess this not very straightforward and can be largely > >>> optimized. Please > >>> give me some hints ? > >>> > >>> Regards, > >>> Jérôme > >>> > >>> > >
