[jira] Commented: (PIG-420) Limit on nothing functionality

["Rekha (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIG-420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12779819#action_12779819 ] 

Rekha commented on PIG-420:
---------------------------

Although the long/int issue of limit is taken care by ticket 3201952, the usecase is a subset need to have debug mode in pig scripts.

I faced similar concern, and wanted a debug mode for usecases like - storing intermediate data only if it is debug, not QA/prod, limit the dataset, applying filters only if debug mode, etc.

I worked around the issue by loading a dummy dataset whose only record -> column would be populated with the passed param value $DEBUG.Depending on the value of this column, processsing was controlled.

Since it was roundabout way, I agree an inbuilt understanding of debug mode in pig scripts would help.Thanks!




> Limit on nothing functionality
> ------------------------------
>
>                 Key: PIG-420
>                 URL: https://issues.apache.org/jira/browse/PIG-420
>             Project: Pig
>          Issue Type: Improvement
>            Reporter: Anand Murugappan
>
> Pig 2.0 implements the limit feature but as a standalone statement. 
> Limit is very useful in debug mode where we could run queries on smaller amount of data (faster and on fewer nodes) to iron out issues but in the production mode we would like to run through all the data. It would be good to have a easy "switch" between debug and prod mode using the limit statement without having to change the underlying code templates. Given that LIMIT is a separate standalone statement it gets hard to parametrize the code. 
> For instance a query template might look like, 
> A = LOAD '...';
> B = LIMIT A $N;
> C = FOREACH B .... 
> In debug mode, we would like to set the variable $N to 100 but in prod mode we would like to set it to a 'special value' that would not apply LIMIT and letting us run it on all the data. 

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