[jira] [Created] (PIG-4018) Schema validation fails with UNION ONSCHEMA

["Travis Woodruff (JIRA)" <ji...@apache.org>]

Travis Woodruff created PIG-4018:
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             Summary: Schema validation fails with UNION ONSCHEMA
                 Key: PIG-4018
                 URL: https://issues.apache.org/jira/browse/PIG-4018
             Project: Pig
          Issue Type: Bug
            Reporter: Travis Woodruff
            Assignee: Travis Woodruff


When relations with differing schemas are unioned (using UNION ONSCHEMA), schema validation can fail with this exception:

{{org.apache.pig.impl.plan.PlanValidationException: Logical plan invalid state: invalid uid -1 in schema}}

This worked before the fix for PIG-3492.

The merged schema (from {{LOUnion.getSchema()}}) does not contain uids for columns not in the schema of the first input (uids are set to -1). This is because only the first input's schema is used for looking up "cached" uids.

Normally, this isn't a problem because {{UnionOnSchemaSetter}} comes along and fixes the missing fields.

However, when {{ImplicitSplitInsertVisitor}} is active, it is called before {{UnionOnSchemaSetter}}. {{ImplicitSplitInsertVisitor}} calls {{schemaResetter.visit()}}, which throws the validation exception because {{UnionOnSchemaSetter}} has not had a chance to create the missing fields (and this uids are still -1 for these fields).



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