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https://issues.apache.org/jira/browse/PIG-1859?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Daniel Dai updated PIG-1859:
----------------------------
Release Note: (was: This is already fixed on 0.8 branch. Please check out
0.8 branch to get the fix:
svn co http://svn.apache.org/repos/asf/pig/branches/branch-0.8)
> Unexpected results from a projection after a union and join
> -----------------------------------------------------------
>
> Key: PIG-1859
> URL: https://issues.apache.org/jira/browse/PIG-1859
> Project: Pig
> Issue Type: Bug
> Components: data
> Affects Versions: 0.8.0
> Environment: Mac OS 10.6.6
> java version "1.6.0_22"
> Java(TM) SE Runtime Environment (build 1.6.0_22-b04-307-10M3261)
> Java HotSpot(TM) 64-Bit Server VM (build 17.1-b03-307, mixed mode)
> Reporter: James Kebinger
> Fix For: 0.8.0
>
>
> Posted this to the pig-users list, and another user indicated he had seen it
> too, so I thought I'd open a ticket. Adding as major because I can't
> workaround the projection issue even with numbered $n column names.
> I have a log file with events on pages, and the id of the event can be a
> users login or a users numeric id:
> 2010-05-14,james
> 2010-05-15,123
> 2010-05-15,23
> 2010-05-15,456
> 2010-05-15,notjames
> So i want to join a set of users on either the login or user id.
> Here's my users:
> 123,james,11
> 234,notjames,11
> 456,someoneelse,11
> So I thought I would be clever and load the user list, union it with itself
> to generate a relation where each user is represented twice, once by login,
> once by id:
> logins = FOREACH users GENERATE LOWER(login) as matching_id, user_id as
> actual_user_id;
> user_ids = FOREACH users GENERATE user_id as matching_id, user_id as
> actual_user_id;
> user_id_or_login_lookup = UNION logins, user_ids;
> user_id_or_login_lookup: {matching_id: chararray,actual_user_id: chararray}
> (123,123)
> (234,234)
> (456,456)
> (james,123)
> (notjames,234)
> (someoneelse,456)
> Then join on that, by the first column, and project that away, leaving just
> the event info and the numeric id.
> views_with_id = JOIN profile_views by viewed_user_id, user_id_or_login_lookup
> by matching_id;
> That is not working however. My joined relation looks like this (which is
> what I expect)
> views_with_id: {profile_views::date: chararray,profile_views::viewed_user_id:
> chararray,user_id_or_login_lookup::matching_id:
> chararray,user_id_or_login_lookup::actual_user_id: chararray}
> (2010-05-15,123,123,123)
> (2010-05-15,456,456,456)
> (2010-05-14,james,james,123)
> (2010-05-15,notjames,notjames,234)
> But when I project as follows: views_with_id_projected = FOREACH
> views_with_id GENERATE date, viewed_user_id,
> user_id_or_login_lookup::actual_user_id;
> The result is not what I expect
> (2010-05-15,123,123)
> (2010-05-15,456,456)
> (2010-05-14,james,james)
> (2010-05-15,notjames,notjames)
> To be clear, I expect
> (2010-05-15,123,123)
> (2010-05-15,456,456)
> (2010-05-14,james,123)
> (2010-05-15,notjames,456)
> Here's my full pig script:
> users = LOAD 'patients-test.txt' USING PigStorage(',') AS (user_id:chararray,
> login:chararray, disease_id: chararray);
> profile_views = LOAD 'patient-views-test.txt' USING PigStorage(',') AS(date:
> chararray, viewed_user_id:chararray);
> dump users;
> dump profile_views;
> -- build a relation so that users are present to join by login or user_id
> logins = FOREACH users GENERATE LOWER(login) as matching_id, user_id as
> actual_user_id;
> user_ids = FOREACH users GENERATE user_id as matching_id, user_id as
> actual_user_id;
> user_id_or_login_lookup = UNION logins, user_ids;
> dump user_id_or_login_lookup;
> describe user_id_or_login_lookup;
> views_with_id = JOIN profile_views by viewed_user_id, user_id_or_login_lookup
> by matching_id;
> describe views_with_id;
> --STORE views_with_id into 'ep-views.txt';
> dump views_with_id;
> views_with_id_projected = FOREACH views_with_id GENERATE date,
> viewed_user_id, user_id_or_login_lookup::actual_user_id;
> dump views_with_id_projected;
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