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Pig, mail # user - Can't JOIN self?


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Russell Jurney 2012-07-20, 02:34
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Russell Jurney 2012-07-20, 02:46
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Robert Yerex 2012-07-20, 03:00
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Russell Jurney 2012-07-20, 03:39
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Re: Can't JOIN self?
Bill Graham 2012-07-20, 04:49
No, to Pig a self join is just like a regular join across two different
relations. It just happens to be to the same input data.

On Thu, Jul 19, 2012 at 8:39 PM, Russell Jurney <[EMAIL PROTECTED]>wrote:

> Is this a bug?
>
> On Thu, Jul 19, 2012 at 8:00 PM, Robert Yerex <
> [EMAIL PROTECTED]> wrote:
>
> > The only way to get it to work is to load a second copy.
> >
> > On Thu, Jul 19, 2012 at 7:46 PM, Russell Jurney <
> [EMAIL PROTECTED]
> > >wrote:
> >
> > > Note: this works if I LOAD a new, 2nd relation and do the join.
> > >
> > > On Thu, Jul 19, 2012 at 7:34 PM, Russell Jurney <
> > [EMAIL PROTECTED]
> > > >wrote:
> > >
> > > > I have a problem where I can't join a relation to itself on a
> different
> > > > field.
> > > >
> > > > describe pairs
> > > > pairs: {from: chararray,to: chararray,message_id:
> > chararray,in_reply_to:
> > > > chararray}
> > > >
> > > > pairs2 = pairs;
> > > >
> > > > with_reply = join pairs by in_reply_to, pairs2 by message_id;
> > > >
> > > >
> > > > I get this error:
> > > >
> > > > 2012-07-19 19:31:16,927 [main] ERROR
> org.apache.pig.tools.grunt.Grunt -
> > > > ERROR 1200: Pig script failed to parse:
> > > > <line 20, column 6> pig script failed to validate:
> > > > org.apache.pig.impl.logicalLayer.FrontendException: ERROR 2225:
> > > Projection
> > > > with nothing to reference!
> > > > 2012-07-19 19:31:16,928 [main] ERROR
> org.apache.pig.tools.grunt.Grunt -
> > > > Failed to parse: Pig script failed to parse:
> > > > <line 20, column 6> pig script failed to validate:
> > > > org.apache.pig.impl.logicalLayer.FrontendException: ERROR 2225:
> > > Projection
> > > > with nothing to reference!
> > > > at
> > > >
> > org.apache.pig.parser.QueryParserDriver.parse(QueryParserDriver.java:182)
> > > >  at org.apache.pig.PigServer$Graph.validateQuery(PigServer.java:1565)
> > > > at org.apache.pig.PigServer$Graph.registerQuery(PigServer.java:1538)
> > > >  at org.apache.pig.PigServer.registerQuery(PigServer.java:540)
> > > > at
> > > org.apache.pig.tools.grunt.GruntParser.processPig(GruntParser.java:970)
> > > >  at
> > > >
> > >
> >
> org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:386)
> > > > at
> > > >
> > >
> >
> org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:189)
> > > >  at
> > > >
> > >
> >
> org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:165)
> > > > at org.apache.pig.tools.grunt.Grunt.run(Grunt.java:69)
> > > >  at org.apache.pig.Main.run(Main.java:490)
> > > > at org.apache.pig.Main.main(Main.java:111)
> > > >  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > > > at
> > > >
> > >
> >
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
> > > >  at
> > > >
> > >
> >
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> > > > at java.lang.reflect.Method.invoke(Method.java:597)
> > > >  at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
> > > > Caused by:
> > > > <line 20, column 6> pig script failed to validate:
> > > > org.apache.pig.impl.logicalLayer.FrontendException: ERROR 2225:
> > > Projection
> > > > with nothing to reference!
> > > >  at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanBuilder.buildJoinOp(LogicalPlanBuilder.java:363)
> > > > at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanGenerator.join_clause(LogicalPlanGenerator.java:11354)
> > > >  at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanGenerator.op_clause(LogicalPlanGenerator.java:1489)
> > > > at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanGenerator.general_statement(LogicalPlanGenerator.java:789)
> > > >  at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanGenerator.statement(LogicalPlanGenerator.java:507)
> > > > at
> > > >
> > >
> >
> org.apache.pig.parser.LogicalPlanGenerator.query(LogicalPlanGenerator.java:382)
> > > >  at
> > > >
> > org.apache.pig.parser.QueryParserDriver.parse(QueryParserDriver.java:175)

*Note that I'm no longer using my Yahoo! email address. Please email me at
[EMAIL PROTECTED] going forward.*
+
Russell Jurney 2012-07-20, 05:10
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Bill Graham 2012-07-20, 05:34
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Dmitriy Ryaboy 2012-07-20, 07:53
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Alan Gates 2012-07-20, 16:01
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Sean Timm 2012-07-23, 21:36
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Russell Jurney 2012-07-23, 21:48
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Russell Jurney 2012-07-24, 08:11