[DRILL-5709] Provide a value vector method to convert a vector to nullable

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.12.0
• Labels: ready-to-commit
• Assignee: Paul Rogers
• Reporter: Paul Rogers
• Reviewer: Boaz Ben-Zvi
• Created: 09/Aug/17 01:11
• Updated: 04/Sep/17 17:30
• Resolved: 04/Sep/17 17:30

Description

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:

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

Issue Links

• links to: GitHub Pull Request #901