[Java] VectorSchemaRoot#addVector() cannot add a vector to the end of the current vector collection

[asfimport]

The current implementation of Java VectorSchemaRoot cannot add a vector at the end of the current list (which is the generally understood meaning of "add").

The Precondition check in the method's second line prevents providing an appropriate index for adding at the end:

public VectorSchemaRoot addVector(int index, FieldVector vector) {
  Preconditions.checkNotNull(vector);
  Preconditions.checkArgument(index >= 0 && index < fieldVectors.size());
  List<FieldVector> newVectors = new ArrayList<>();
  for (int i = 0; i < fieldVectors.size(); i++) {
    if (i == index) {
      newVectors.add(vector);
    }
    newVectors.add(fieldVectors.get(i));
  }
  return new VectorSchemaRoot(newVectors);
}
 

One possible implementation resolving the issue is shown below.

public VectorSchemaRoot addVector(int index, FieldVector vector) {
  Preconditions.checkNotNull(vector);
  Preconditions.checkArgument(index >= 0 && index <= fieldVectors.size());
  List<FieldVector> newVectors = new ArrayList<>();
  if (index == fieldVectors.size()) {
    newVectors.addAll(fieldVectors);
    newVectors.add(vector); 
  } else {
    for (int i = 0; i < fieldVectors.size(); i++) {
      if (i == index) {
        newVectors.add(vector);
      }
      newVectors.add(fieldVectors.get(i));
    }
  }
  return new VectorSchemaRoot(newVectors);
}

 

 

 

 

 

Reporter: Larry White / @lwhite1

_{Note: This issue was originally created as ARROW-17530. Please see the migration documentation for further details.}

[asfimport]

Apache Arrow JIRA Bot:
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[jjbskir]

Hey, I noticed the same issue recently on this line of code as well. Is this expected behavior? If I have an existing VectorSchemaRoot and want to add a new FieldVector to it is there a better way to do it?

Happy to put up a CR to address the issue as well.

[lidavidm]

I suppose you can always create a new root, but given the existence of the method I would support fixing this too. PRs are welcome.

[jjbskir]

Sounds good! Will look into putting up a PR for this.