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Pig >> mail # user >> Problems with union, projection producing unexpected results


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Re: Problems with union, projection producing unexpected results
Interesting, maybe I should file a bug report then?

On Thu, Feb 17, 2011 at 10:41 AM, Jonathan Coveney <[EMAIL PROTECTED]>wrote:

> I am glad that you got this in a replicatable form! I have seen this error
> as well (where the output is just the last value repeated instead of the
> multiples that you want), but wasn't able to give a concrete example.
>
> 2011/2/16 James Kebinger <[EMAIL PROTECTED]>
>
> > Hello all, I've been scratching my head over a problem with a pig script
> > I'm
> > having, and hoping another set of eyeballs will help. I'm using pig 0.8,
> in
> > local mode
> >
> > Here's my simplified use case:
> >
> > 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)
> >
> >
> > Can anyone give me a push in the right direction?
> >
> > Thanks, James
> >
> > 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;
> >
>