/**
* Returns the user-defined split order, or dimensions in order of descending cardinality (removes
* excludes too)
*/
private List<String> computeSplitOrder(final Map<String, ColumnIndexCreationInfo> columnInfo) {
List<String> splitOrder;
if (starTreeIndexSpec.getSplitOrder() == null) {
splitOrder = new ArrayList<String>(schema.getDimensionNames());
Collections.sort(
splitOrder,
new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
Object[] o1UniqueElements = columnInfo.get(o1).getSortedUniqueElementsArray();
Object[] o2UniqueElements = columnInfo.get(o2).getSortedUniqueElementsArray();
return o2UniqueElements.length - o1UniqueElements.length; // descending
}
});
} else {
splitOrder = new ArrayList<String>(starTreeIndexSpec.getSplitOrder());
}
if (starTreeIndexSpec.getSplitExcludes() != null) {
splitOrder.removeAll(starTreeIndexSpec.getSplitExcludes());
}
return splitOrder;
}
