Paul Rogers created DRILL-5709:
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Summary: Provide a value vector method to convert a vector to
nullable
Key: DRILL-5709
URL: https://issues.apache.org/jira/browse/DRILL-5709
Project: Apache Drill
Issue Type: Improvement
Reporter: Paul Rogers
Assignee: Paul Rogers
Fix For: 1.12.0
The hash agg spill work has need to convert a non-null scalar vector to the
nullable equivalent. For efficiency, the code wishes to simply transfer the
underlying data buffer(s), and create the required "bits" vector, rather than
generating code that does the transfer row-by-row.
The solution is to add a {{toNullable(ValueVector nullableVector)}} method to
the {{ValueVector}} class, then implement it where needed.
Since the target code only works with scalars (that is, no arrays, no maps, no
lists), the code only handles these cases, throwing an
{{UnsupportedOperationException}} in other cases.
Usage:
{code}
ValueVector nonNullableVector = // your non-nullable vector
MajorType type = MajorType.newBuilder(nonNullableVector.getType)
.setMode(DataMode.OPTIONAL)
.build();
MaterializedField field = MaterializedField.create(name, type);
ValueVector nullableVector = TypeHelper.getNewVector(field,
oContext.getAllocator());
nonNullableVector.toNullable(nullableVector);
// Data is now in nullableVector
{code}
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