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Posted to dev@pig.apache.org by "Santhosh Srinivasan (JIRA)" <ji...@apache.org> on 2008/09/23 04:46:44 UTC
[jira] Created: (PIG-449) Schemas for bags should contain tuples
all the time
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: 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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[jira] Commented: (PIG-449) Schemas for bags should contain tuples
all the time
Posted by "Pradeep Kamath (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/PIG-449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12635050#action_12635050 ]
Pradeep Kamath commented on PIG-449:
------------------------------------
Another script snippet which shows the above inconsistency:
{code}
grunt> a = load 'bla' as (b:bag{t:(x,y,z)}, t:tuple(a,b,c), m:[]);
grunt> describe a;
a: {b: {t: (x: bytearray,y: bytearray,z: bytearray)},t: (a: bytearray,b: bytearray,c: bytearray),m: map[ ]}
grunt> b = foreach a generate b.y;
2008-09-26 15:35:22,673 [main] ERROR org.apache.pig.tools.grunt.GruntParser - java.io.IOException: Invalid alias: y in {t: (x: bytearray,y: bytearray,z: bytearray)}
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:434)
at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:242)
at org.apache.pig.tools.grunt.GruntParser.parseContOnError(GruntParser.java:94)
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: y in {t: (x: bytearray,y: bytearray,z: bytearray)}
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
2008-09-26 15:35:22,674 [main] ERROR org.apache.pig.tools.grunt.GruntParser - Invalid alias: y in {t: (x: bytearray,y: bytearray,z: bytearray)}
2008-09-26 15:35:22,674 [main] ERROR org.apache.pig.tools.grunt.GruntParser - java.io.IOException: Invalid alias: y in {t: (x: bytearray,y: bytearray,z: bytearray)}
grunt> b = foreach a generate b.t.y;
grunt> describe b;
b: {y: {y: bytearray}} --> THIS ALSO LOOKS WRONG
{code}
> 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: 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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[jira] Commented: (PIG-449) Schemas for bags should contain tuples
all the time
Posted by "Santhosh Srinivasan (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/PIG-449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12646712#action_12646712 ]
Santhosh Srinivasan commented on PIG-449:
-----------------------------------------
Currently, bags in Pig are containers of tuples. Accessing elements inside a bag should translate to accessing elements inside the tuple contained in the bag. In addition, accessing tuples inside a bag should be restricted to the FLATTEN keyword in a FOREACH statement. A few examples shown below will demonstrate the point.
{code}
a = load '/user/pig/data/student.data' using PigStorage(' ') as (name, age, gpa);
b = foreach a generate {(16, 4.0e-2, 'hello')} as b:{t:(i: int, d: double, c: chararray)};
c = foreach b generate b.i; -- Here b.i should generate a bag of integers by accessing the column called 'i' inside each tuple
d = foeach b generate b.t; -- This should be outlawed as the tuple inside the bag does not have a column called 't' although the tuple inside the bag are named 't'
{code}
Summary:
1. The frontend should translate access to columns in a bag to columns inside the tuple in the bag
2. The frontend should prevent access to tuples inside the bag via projections and allow access only via the FLATTEN keyword
Thoughts/suggestions/comments are welcome.
> 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: 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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