It servers two purposes: 1. divide the group into smaller subgroups 2. make sure distinct in subgroup => distinct in group
Shawn On Fri, May 20, 2011 at 2:20 PM, sonia gehlot <[email protected]> wrote: > Hey, I am sorry but I din't get how substring will help in this? > > On Fri, May 20, 2011 at 1:08 PM, Xiaomeng Wan <[email protected]> wrote: > >> you can try using some divide and conquer, like this: >> >> a = group data by (key, SUBSTRING(the_field_to_be_distinct, 0, 2)); >> b = foreach a { x = distinct a.he_field_to_be_distinct; generate >> group.key as key, COUNT(x) as cnt; } >> c = group b by key; >> d = foreach c generate group as key, SUM(b.cnt) as cnt; >> >> using longer substring if still running into OOM. >> >> Regards, >> Shawn >> >> On Fri, May 20, 2011 at 1:11 PM, sonia gehlot <[email protected]> >> wrote: >> > Hey Thejas, >> > >> > I tried setting up property pig.cachedbag.memusage to 0.1 and also tried >> > computing distinct count for each type separately but still I am getting >> > errors like >> > >> > Error: java.lang.OutOfMemoryError: Java heap space >> > Caused by: java.lang.OutOfMemoryError: GC overhead limit exceeded >> > java.io.IOException: Spill failed >> > >> > Is there is some other way to do distinct - count that you may suggest? >> > >> > Thanks for your help. >> > >> > Sonia >> > >> > On Fri, May 13, 2011 at 4:46 PM, Thejas M Nair <[email protected]> >> wrote: >> > >> >> The stack trace shows that the OOM error is happening when the distinct >> is >> >> being applied. It looks like in some record(s) of the relation group_it, >> >> one >> >> more of the following bags is very large - logic.c_users, >> logic.nc_users >> >> or >> >> logic.registered_users; >> >> >> >> Try setting the property pig.cachedbag.memusage to 0.1 or lower ( >> >> -Dpig.cachedbag.memusage=0.1 on java command line). It controls the >> memory >> >> used by pig internal bags, including those used by distinct. >> >> >> >> If that does not work, you can try computing count-distinct for each >> type >> >> of >> >> user separately and then combining the result. >> >> >> >> >> >> You might want to have a look at this way of optimizing count-distinct >> >> queries where skew can be a problem - >> >> https://issues.apache.org/jira/browse/PIG-1846 >> >> >> >> -thejas >> >> >> >> >> >> >> >> >> >> >> >> On 5/12/11 10:43 AM, "sonia gehlot" <[email protected]> wrote: >> >> >> >> > Hi Guys, >> >> > >> >> > I am running following Pig script in Pig 0.8 version >> >> > >> >> > page_events = LOAD '/user/sgehlot/day=2011-05-10' as >> >> > >> >> >> (event_dt_ht:chararray,event_dt_ut:chararray,event_rec_num:int,event_type:int, >> >> > >> >> >> client_ip_addr:long,hub_id:int,is_cookied_user:int,local_ontology_node_id:int, >> >> > >> >> >> page_type_id:int,content_id:int,product_id:int,referrer_edition_id:int,page_nu >> >> > >> >> >> mber:int,is_iab_robot:int,browser_id:int,os_id:int,dw_pubsys_id:int,refresh:in >> >> > >> >> >> t,asset_id:int,asset_type_id:int,content_type_id:int,product_type_id:int,outbo >> >> > >> >> >> und_email_id:long,gbal_clc:int,mtype:int,user_action_id:int,referring_partner_ >> >> > >> >> >> id:int,ontology_node_id:int,content_namespace_id:int,product_namespace_id:int, >> >> > >> >> >> transparent_edition_id:int,default_edition_id:int,event_seq_num:int,is_last_pa >> >> > >> >> >> ge:int,is_new_user:int,page_duration:int,page_seq_num:int,session_id:long,time >> >> > >> >> >> _since_sess_start:int,reg_cookie:chararray,urs_app_id:int,is_reg_user:int,edit >> >> > >> >> >> ion_id:int,user_agent_id:int,page_type_key:int,referrer_id:int,channel_id:int, >> >> > >> >> >> level2_id:int,level3_id:int,brand_id:int,content_key:int,product_key:int,editi >> >> > >> >> >> on_key:int,partner_key:int,business_unit_id:int,anon_cookie:chararray,machine_ >> >> > >> >> >> name:chararray,pagehost:chararray,filenameextension:chararray,referrerpath:cha >> >> > >> >> >> rarray,referrerhost:chararray,referring_oid:chararray,referring_legacy_oid:cha >> >> > >> >> >> rarray,ctype:chararray,cval:chararray,link_tag:chararray,link_type:chararray,s >> >> > >> >> >> ticky_tag:chararray,page_url:chararray,search_category:chararray,partner_subje >> >> > >> >> >> ct:chararray,referring_partner_name:chararray,robot_pattern:chararray,browser: >> >> > >> >> >> chararray,browser_major_version:chararray,browser_minor_version:chararray,os:c >> >> > >> >> >> hararray,os_family:chararray,ttag:chararray,dest_oid:chararray,global_id:chara >> >> > >> >> >> rray,hostname:chararray,path:chararray,filename:chararray,extension:chararray, >> >> > >> >> >> query:chararray,user_agent:chararray,xrq:chararray,xref:chararray,page_guid:ch >> >> > >> >> >> ararray,test_name:chararray,test_group:chararray,test_version:chararray,page_v >> >> > >> >> >> ersion:chararray,o_sticky_tag:chararray,new_referring_oid:chararray,day:charar >> >> > >> >> >> ray,network_ip:int,site_id:int,search_phrase:chararray,search_attributes:chara >> >> > >> >> >> rray,web_search_phrase:chararray,ip_address:chararray,is_pattern_match_robot:i >> >> > >> >> >> nt,protocol:chararray,skc_title:chararray,skc_url:chararray,has_site_search_ph >> >> > >> >> >> rase:int,has_site_search_attribs:int,has_web_search_phrase:int,title_id:charar >> >> > ray,url_id:chararray,network_rev:int); >> >> > >> >> > referrer_group_map = LOAD >> >> '/user/sgehlot/oozie/db_data/referrer_group_map' >> >> > as >> >> > (referrer_id:int, has_web_search_phrase:int, hostname:chararray, >> >> > referral_type_id:int, >> >> > referral_type_name:chararray, >> >> > >> >> >> referrer_group_id:int,referrer_group_name:chararray,referrer_group_cat_id:int, >> >> > referrer_group_cat:chararray); >> >> > >> >> > filter_pe = FILTER page_events BY is_iab_robot == 0 AND >> >> > is_pattern_match_robot == 0 AND day == '2011-05-10'; >> >> > >> >> > select_pe_col = FOREACH filter_pe GENERATE day, is_cookied_user, >> >> > anon_cookie, reg_cookie, referrer_id, has_web_search_phrase, >> >> > business_unit_id; >> >> > >> >> > select_ref_col = FOREACH referrer_group_map GENERATE referrer_id, >> >> > has_web_search_phrase, referral_type_id; >> >> > >> >> > jn = JOIN select_ref_col BY (referrer_id, has_web_search_phrase), >> >> > select_pe_col BY (referrer_id, has_web_search_phrase); >> >> > >> >> > >> >> > logic = FOREACH jn GENERATE >> >> > select_pe_col::day, >> >> > select_ref_col::referral_type_id, >> >> > select_pe_col::business_unit_id, >> >> > ((select_pe_col::is_cookied_user == 1) ? select_pe_col::anon_cookie : >> >> null) >> >> > as c_users, >> >> > ((select_pe_col::is_cookied_user == 0) ? select_pe_col::anon_cookie : >> >> null) >> >> > as nc_users, >> >> > ((select_pe_col::reg_cookie == '-1') ? null : >> select_pe_col::reg_cookie) >> >> as >> >> > registered_users; >> >> > group_it = GROUP logic BY (select_pe_col::day, >> >> > select_ref_col::referral_type_id, >> >> > select_pe_col::business_unit_id); >> >> > >> >> > agg_results = FOREACH group_it{ >> >> > dst_c_users = DISTINCT logic.c_users; >> >> > dst_nc_users = DISTINCT logic.nc_users; >> >> > dst_registered_users = DISTINCT logic.registered_users; >> >> > GENERATE >> >> > group.select_pe_col::day, >> >> > group.select_ref_col::referral_type_id, >> >> > group.select_pe_col::business_unit_id, >> >> > COUNT(dst_c_users) as c_users, >> >> > COUNT(dst_nc_users) as nc_users, >> >> > COUNT(dst_registered_users) as registered_users; >> >> > }; >> >> > >> >> > STORE agg_results INTO '/user/sgehlot/pt_users_referral_type_bu_day' >> >> USING >> >> > PigStorage('\t'); >> >> > >> >> > >> >> > But I am keep on failing because of Java out of memory error. Data set >> in >> >> > "page_events" is huge but in "referrer_group_map" is relatively very >> >> less. >> >> > >> >> > Here is error message: >> >> > >> >> > Error: java.lang.OutOfMemoryError: GC overhead limit exceeded >> >> > at java.util.ArrayList.(ArrayList.java:112) >> >> > at java.util.ArrayList.(ArrayList.java:119) >> >> > at org.apache.pig.data.DefaultTuple.(DefaultTuple.java:59) >> >> > at org.apache.pig.data.BinSedesTuple.(BinSedesTuple.java:73) >> >> > at >> >> > >> >> >> >> >> org.apache.pig.data.BinSedesTupleFactory.newTuple(BinSedesTupleFactory.java:33> >> >> ) >> >> > at >> >> > >> >> >> org.apache.pig.data.InternalCachedBag$CachedBagIterator.hasNext(InternalCached >> >> > Bag.java:236) >> >> > at >> >> > >> >> >> org.apache.pig.builtin.Distinct.getDistinctFromNestedBags(Distinct.java:136) >> >> > at org.apache.pig.builtin.Distinct.access$200(Distinct.java:38) >> >> > at >> org.apache.pig.builtin.Distinct$Intermediate.exec(Distinct.java:101) >> >> > at >> org.apache.pig.builtin.Distinct$Intermediate.exec(Distinct.java:94) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperator >> >> > s.POUserFunc.getNext(POUserFunc.java:216) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperator >> >> > s.POUserFunc.getNext(POUserFunc.java:253) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.g >> >> > etNext(PhysicalOperator.java:334) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator >> >> > s.POForEach.processPlan(POForEach.java:332) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator >> >> > s.POForEach.getNext(POForEach.java:284) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.p >> >> > rocessInput(PhysicalOperator.java:290) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator >> >> > s.POLocalRearrange.getNext(POLocalRearrange.java:256) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.processOnePackageOutput(PigCombiner.java:184) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.reduce(PigCombiner.java:162) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.reduce(PigCombiner.java:51) >> >> > at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176) >> >> > at >> >> org.apache.hadoop.mapred.Task$NewCombinerRunner.combine(Task.java:1222) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:126 >> >> > 5) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:686) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java: >> >> > 1173) >> >> > >> >> > Error: java.lang.OutOfMemoryError: Java heap space >> >> > at java.util.ArrayList.(ArrayList.java:112) >> >> > at java.util.ArrayList.(ArrayList.java:119) >> >> > at org.apache.pig.data.DefaultDataBag.(DefaultDataBag.java:54) >> >> > at >> >> > >> >> >> org.apache.pig.data.DefaultBagFactory.newDefaultBag(DefaultBagFactory.java:33) >> >> > at org.apache.pig.data.BinInterSedes.readBag(BinInterSedes.java:143) >> >> > at >> org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:275) >> >> > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:251) >> >> > at >> org.apache.pig.data.BinInterSedes.readTuple(BinInterSedes.java:111) >> >> > at org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:270) >> >> > at >> org.apache.pig.data.BinInterSedes.readDatum(BinInterSedes.java:251) >> >> > at >> >> org.apache.pig.data.BinInterSedes.addColsToTuple(BinInterSedes.java:555) >> >> > at >> org.apache.pig.data.BinSedesTuple.readFields(BinSedesTuple.java:64) >> >> > at >> >> > >> >> >> org.apache.pig.impl.io.PigNullableWritable.readFields(PigNullableWritable.java >> >> > :114) >> >> > at >> >> > >> >> >> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.des >> >> > erialize(WritableSerialization.java:67) >> >> > at >> >> > >> >> >> org.apache.hadoop.io.serializer.WritableSerialization$WritableDeserializer.des >> >> > erialize(WritableSerialization.java:40) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapreduce.ReduceContext.nextKeyValue(ReduceContext.java:116) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapreduce.ReduceContext$ValueIterator.next(ReduceContext.jav >> >> > a:163) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperator >> >> > s.POCombinerPackage.getNext(POCombinerPackage.java:141) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.processOnePackageOutput(PigCombiner.java:171) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.reduce(PigCombiner.java:162) >> >> > at >> >> > >> >> >> org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigCombiner$Combi >> >> > ne.reduce(PigCombiner.java:51) >> >> > at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176) >> >> > at >> >> org.apache.hadoop.mapred.Task$NewCombinerRunner.combine(Task.java:1222) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:126 >> >> > 5) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.access$1800(MapTask.java:686) >> >> > at >> >> > >> >> >> org.apache.hadoop.mapred.MapTask$MapOutputBuffer$SpillThread.run(MapTask.java: >> >> > 1173) >> >> > >> >> > Any idea and suggestion what could be cause of error message? >> >> > >> >> > Thanks for any help, >> >> > Sonia >> >> > >> >> >> >> >> >> -- >> >> >> >> >> >> >> > >> >
