int count = copier.next(targetRecordCount);
assert count > 0;
VectorContainer c1 = VectorContainer.getTransferClone(outputContainer);
c1.buildSchema(BatchSchema.SelectionVectorMode.NONE);
c1.setRecordCount(count);
String outputFile = String.format(Utilities.getFileNameForQueryFragment(context, dirs.next(), "spill" + uid + "_" + spillCount++));
BatchGroup newGroup = new BatchGroup(c1, fs, outputFile, oContext.getAllocator());