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
>> >
>>
>>
>> --
>>
>>
>>
>
