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From "George Mavromatis (JIRA)" <j...@apache.org>
Subject [jira] Updated: (PIG-812) COUNT(*) does not work
Date Wed, 19 Aug 2009 18:28:14 GMT

     [ https://issues.apache.org/jira/browse/PIG-812?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

George Mavromatis updated PIG-812:
----------------------------------


First, I have to say that the updated documentation specifies adequately further undocumented
but important details of pig syntax and behavior (e.g. dereference) in addition to the ones
mentioned in this ticket. Very good job! This will improve usability of pig significantly.
Thank you.

Regarding the particular points in this ticket:

1) Description is adequate for pig. Contrast with sql is nice to have, not crucial.
2) These parts were probably edited by Corinne. Examples may help, but again the spec is important
to have and that was addressed.
3) 'key' or key should be consistent in both "symbol" and "notes" sections.
4) I think the parenthesis pair is correct. This specification of flatten is quite clear!
5) No opinion.


> COUNT(*) does not work 
> -----------------------
>
>                 Key: PIG-812
>                 URL: https://issues.apache.org/jira/browse/PIG-812
>             Project: Pig
>          Issue Type: Bug
>          Components: impl
>    Affects Versions: 0.2.0
>            Reporter: Viraj Bhat
>            Assignee: Benjamin Reed
>             Fix For: 0.2.0
>
>         Attachments: PIG-812.patch, PIG-812.patch, PIG-812.pdf, studenttab10k
>
>
> Pig script to count the number of rows in a studenttab10k file which contains 10k records.
> {code}
> studenttab = LOAD 'studenttab10k' AS (name:chararray, age:int,gpa:float);
> X2 = GROUP studenttab ALL;
> describe X2;
> Y2 = FOREACH X2 GENERATE COUNT(*);
> explain Y2;
> DUMP Y2;
> {code}
> returns the following error
> ================================================================
> ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias
Y2
> Details at logfile: /homes/viraj/pig-svn/trunk/pig_1242783700970.log
> ================================================================
> If you look at the log file:
> ================================================================
> Caused by: java.lang.ClassCastException
>         at org.apache.pig.builtin.COUNT$Initial.exec(COUNT.java:76)
>         at org.apache.pig.builtin.COUNT$Initial.exec(COUNT.java:68)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:201)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.expressionOperators.POUserFunc.getNext(POUserFunc.java:235)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.processPlan(POForEach.java:254)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POForEach.getNext(POForEach.java:204)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator.processInput(PhysicalOperator.java:231)
>         at org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.POLocalRearrange.getNext(POLocalRearrange.java:223)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.runPipeline(PigMapBase.java:245)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapBase.map(PigMapBase.java:236)
>         at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.PigMapReduce$Map.map(PigMapReduce.java:88)
>         at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:47)
>         at org.apache.hadoop.mapred.MapTask.run(MapTask.java:227)
> ================================================================

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