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https://issues.apache.org/jira/browse/PIG-826?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12715745#action_12715745
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Mridul Muralidharan commented on PIG-826:
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This would be a welcome change !
Another usecase which would get enabled (which, imo cant be done 'easily' now) 
is to use DISTINCT in filter.

Like :

B = FILTER A by COUNT(DISTINCT($1)) > 1;





> DISTINCT as "Function/Operator" rather than statement/operator - High Level 
> Pig
> -------------------------------------------------------------------------------
>
>                 Key: PIG-826
>                 URL: https://issues.apache.org/jira/browse/PIG-826
>             Project: Pig
>          Issue Type: New Feature
>            Reporter: David Ciemiewicz
>
> In SQL, a user would think nothing of doing something like:
> {code}
> select
>     COUNT(DISTINCT(user)) as user_count,
>     COUNT(DISTINCT(country)) as country_count,
>     COUNT(DISTINCT(url) as url_count
> from
>     server_logs;
> {code}
> But in Pig, we'd need to do something like the following.  And this is about 
> the most
> compact version I could come up with.
> {code}
> Logs = load 'log' using PigStorage()
>         as ( user: chararray, country: chararray, url: chararray);
> DistinctUsers = distinct (foreach Logs generate user);
> DistinctCountries = distinct (foreach Logs generate country);
> DistinctUrls = distinct (foreach Logs generate url);
> DistinctUsersCount = foreach (group DistinctUsers all) generate
>         group, COUNT(DistinctUsers) as user_count;
> DistinctCountriesCount = foreach (group DistinctCountries all) generate
>         group, COUNT(DistinctCountries) as country_count;
> DistinctUrlCount = foreach (group DistinctUrls all) generate
>         group, COUNT(DistinctUrls) as url_count;
> AllDistinctCounts = cross
>         DistinctUsersCount, DistinctCountriesCount, DistinctUrlCount;
> Report = foreach AllDistinctCounts generate
>         DistinctUsersCount::user_count,
>         DistinctCountriesCount::country_count,
>         DistinctUrlCount::url_count;
> store Report into 'log_report' using PigStorage();
> {code}
> It would be good if there was a higher level version of Pig that permitted 
> code to be written as:
> {code}
> Logs = load 'log' using PigStorage()
>         as ( user: chararray, country: chararray, url: chararray);
> Report = overall Logs generate
>         COUNT(DISTINCT(user)) as user_count,
>         COUNT(DISTINCT(country)) as country_count,
>         COUNT(DISTINCT(url)) as url_count;
> store Report into 'log_report' using PigStorage();
> {code}
> I do want this in Pig and not as SQL.  I'd expect High Level Pig to generate 
> Lower Level Pig.

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