Schemas for bags should contain tuples all the time
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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: Santhosh Srinivasan
Fix For: types_branch
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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