Daniel Barclay (Drill) created DRILL-4010:
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Summary: In HBase reader, create child vectors for referenced HBase columns to
avoid spurious schema changes
Key: DRILL-4010
URL: https://issues.apache.org/jira/browse/DRILL-4010
Project: Apache Drill
Issue Type: Bug
Components: Execution - Data Types, Storage - HBase
Reporter: Daniel Barclay (Drill)
{{HBaseRecordReader}} needs to create child vectors for all referenced/requested columns.
Currently, if a fragment reads only HBase rows that don't have a particular referenced column
(within a given column family), downstream code adds a dummy column of type {{NullableIntVector}}
(as a child in the {{MapVector}} for the containing HBase column family).
If any other fragment reads an HBase row that _does_ contain the referenced column, that fragment's
reader will create a child {{NullableVarBinaryVector}} for the referenced column.
When the data from those two fragments comes together, Drill detects a schema change, even
though logically there isn't really any schema change.
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