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From "Pradeep Kamath (JIRA)" <j...@apache.org>
Subject [jira] Updated: (PIG-449) Schemas for bags should contain tuples all the time
Date Mon, 08 Dec 2008 23:03:44 GMT

     [ https://issues.apache.org/jira/browse/PIG-449?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Pradeep Kamath updated PIG-449:
-------------------------------

    Attachment: PIG-449.patch

> Schemas for bags should contain tuples all the time
> ---------------------------------------------------
>
>                 Key: PIG-449
>                 URL: https://issues.apache.org/jira/browse/PIG-449
>             Project: Pig
>          Issue Type: Bug
>    Affects Versions: types_branch
>            Reporter: Santhosh Srinivasan
>            Assignee: Pradeep Kamath
>             Fix For: types_branch
>
>         Attachments: PIG-449.patch
>
>
> The front end treats relations as operators that return bags.  When the schema of a load
statement is specified, the bag is associated with the schema specified by the user. Ideally,
the schema corresponds to the tuple contained in the bag. 
> With PIG-380, the schema for bag constants are computed by the front end. The schema
for the bag contains the tuple which in turn contains the schema of the columns. This results
in errors when columns are accessed directly just like the load statements.
> The front end should then treat access to the columns as a double dereference, i.e.,
access the tuple inside the bag and then the column inside the tuple.
> {code}
> grunt> a = load '/user/sms/data/student.data' using PigStorage(' ') as (name, age,
gpa);
> grunt> b = foreach a generate {(16, 4.0e-2, 'hello')} as b:{t:(i: int, d: double,
c: chararray)};
> grunt> describe b;
> b: {b: {t: (i: integer,d: double,c: chararray)}}
> grunt> c = foreach b generate b.i;
> 111064 [main] ERROR org.apache.pig.tools.grunt.GruntParser  - java.io.IOException: Invalid
alias: i in {t: (i: integer,d: double,c: chararray)}
>         at org.apache.pig.PigServer.parseQuery(PigServer.java:293)
>         at org.apache.pig.PigServer.registerQuery(PigServer.java:258)
>         at org.apache.pig.tools.grunt.GruntParser.processPig(GruntParser.java:432)
>         at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:242)
>         at org.apache.pig.tools.grunt.GruntParser.parseContOnError(GruntParser.java:93)
>         at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:58)
>         at org.apache.pig.Main.main(Main.java:282)
> Caused by: org.apache.pig.impl.logicalLayer.parser.ParseException: Invalid alias: i in
{t: (i: integer,d: double,c: chararray)}
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.AliasFieldOrSpec(QueryParser.java:5851)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.ColOrSpec(QueryParser.java:5709)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.BracketedSimpleProj(QueryParser.java:5242)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.BaseEvalSpec(QueryParser.java:4040)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.UnaryExpr(QueryParser.java:3909)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.CastExpr(QueryParser.java:3863)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.MultiplicativeExpr(QueryParser.java:3772)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.AdditiveExpr(QueryParser.java:3698)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.InfixExpr(QueryParser.java:3664)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.FlattenedGenerateItem(QueryParser.java:3590)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.FlattenedGenerateItemList(QueryParser.java:3500)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.GenerateStatement(QueryParser.java:3457)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.NestedBlock(QueryParser.java:2933)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.ForEachClause(QueryParser.java:2336)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.BaseExpr(QueryParser.java:973)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.Expr(QueryParser.java:748)
>         at org.apache.pig.impl.logicalLayer.parser.QueryParser.Parse(QueryParser.java:549)
>         at org.apache.pig.impl.logicalLayer.LogicalPlanBuilder.parse(LogicalPlanBuilder.java:60)
>         at org.apache.pig.PigServer.parseQuery(PigServer.java:290)
>         ... 6 more
> 111064 [main] ERROR org.apache.pig.tools.grunt.GruntParser  - Invalid alias: i in {t:
(i: integer,d: double,c: chararray)}
> 111064 [main] ERROR org.apache.pig.tools.grunt.GruntParser  - java.io.IOException: Invalid
alias: i in {t: (i: integer,d: double,c: chararray)}
> grunt> c = foreach b generate b.t;
> grunt> describe c;
> c: {t: {i: integer,d: double,c: chararray}}
> {code}

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