Hanifi Gunes created DRILL-2147:
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Summary: Refactor ValueVector design
Key: DRILL-2147
URL: https://issues.apache.org/jira/browse/DRILL-2147
Project: Apache Drill
Issue Type: Bug
Reporter: Hanifi Gunes
Assignee: Hanifi Gunes
The overall design of value vectors has become unclear and inconsistent with
additions from multiple contributors over the time. Also we need proper
documentation for the abstractions made for consistently communicating with
developers.
There are many instances that indicate possible design issues.
For instance, ValueVector implements Iterator<ValueVector>. This seems to
assume all vectors are somewhat hierarchical. This does not truly capture
scalar vectors as they have no child.
Similarly, RepeatedVector has the following interface definition:
{code:title=RepeatedVector}
interface RepeatedVector {
RepeatedFixedWidthVector.RepeatedAccessor getAccessor()
}
{code}
Yet, RepeatedFixedWidthVector implements RepeatedVector as follows
{code:title=RepeatedFixedWidthVector}
interface RepeatedFixedWidthVector extends ValueVector, RepeatedVector {
interface RepeatedAccessor extends Accessor {...}
interface RepeatedMutator extends Mutator {...}
}
{code}
A super-type that is aware of its sub-type hints a need for re-design.
Examples could be multiplied here: some method names are not self-explaining or
wrongly named or seems to be misplaced. There are couple of more places where
design is not capturing the nature of vectors such like missing abstractions
for Repeated vs Composite vectors. We should consider a design refactoring.
This is an umbrella issue for tracking ValueVector design refactoring.
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