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https://issues.apache.org/jira/browse/PIG-1536?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Daniel Dai updated PIG-1536:
----------------------------
Release Note:
The behavior of union and uniononschema converges after this patch:
1. Union on relation of two different size result a null schema (union only):
A: (a1:long, a2:long)
B: (b1:long, b2:long, b3:long)
A union B: null
2. Union column of incompatible type result a bytearray type:
A: (a1:long, a2:long)
B: (b1:(b11:long, b12:long), b2:long)
A union B: (a1:bytearray, a2:long)
3. Union column of compatible type will produce a escalate the type. The
priority is chararray -> double -> float -> long -> int:
A: (a1:int, a2:double)
B: (b1:float, b2:chararray)
A union B: (a1:float, a2:chararray)
4. Union different inner type result an empty complex type:
A: (a1:(a11:long, a12:int), a2:{(a21:charray, a22:int)})
B: (b1:(b11:int, b12:int), b2:{(b21:int, b22:int)})
A union B: (a1:(), a2:{()})
5. Always take the alias of first relation as the alias of unioned relation
field
> use same logic for merging inner schemas in "default union" and "union
> onschema"
> --------------------------------------------------------------------------------
>
> Key: PIG-1536
> URL: https://issues.apache.org/jira/browse/PIG-1536
> Project: Pig
> Issue Type: Task
> Reporter: Thejas M Nair
> Assignee: Daniel Dai
> Fix For: 0.9.0
>
> Attachments: PIG-1536-1.patch
>
>
> We should consider using logic for merging inner schema in case of the two
> different types of union.
> In case of 'default union', it merges the two inner schema of bags/tuples by
> position if the number of fields are same and the corresponding types are
> compatible.
> In case of 'union onschema', it considers tuple/bag with different
> innerschema to be incompatible types.
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