Daniel Barclay (Drill) created DRILL-3955:
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Summary: Possible bug in creation of Drill columns for HBase column families
Key: DRILL-3955
URL: https://issues.apache.org/jira/browse/DRILL-3955
Project: Apache Drill
Issue Type: Bug
Reporter: Daniel Barclay (Drill)
If all of the rows read by a given {{HBaseRecordReader}} have no HBase columns in a given
HBase column family, {{HBaseRecordReader}} doesn't create a Drill column for that HBase column
family.
Later, in a {{ProjectRecordBatch}}'s {{setupNewSchema}}, because no Drill column exists for
that HBase column family, that {{setupNewSchema}} creates a dummy Drill column using the usual
{{NullableIntVector}} type. In particular, it is not a map vector as {{HBaseRecordReader}}
creates when it sees an HBase column family.
Should {{HBaseRecordReader}} and/or something around setting up for reading HBase (including
setting up that {{ProjectRecordBatch}}) make sure that all HBase column families are represented
with map vectors so that {{setupNewSchema}} doesn't create a dummy field of type {{NullableIntVector}}?
The problem is that, currently, when an HBase table is read in two separate fragments, one
fragment (seeing rows with columns in the column family) can get a map vector for the column
family while the other (seeing only rows with no columns in the column familar) can get the
{{NullableIntVector}}. Downstream code that receives the two batches ends up with an unresolved
conflict, yielding IndexOutOfBoundsExceptions as in DRILL-3954.
It's not clear whether there is only one bug--that downstream code doesn't resolve {{NullableIntValue}}
dummy fields right (DRILL-TBD)--or two--that the HBase reading code should set up a Drill
column for every HBase column family (regardless of whether it has any columns in the rows
that were read) and that downstream code doesn't resolve {{NullableIntValue}} dummy fields
(resolution is applicable to sources other than just HBase).
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