/**
* Scan the given index query and add the results to the provided set. The set comparator of the
* dynamic columns are compared via a tree comparator
*
* @param query
* @return
*/
public ScanBuffer scanIndex(IndexQuery query, Keyspace keyspace) {
DynamicComposite startScan = newComposite();
DynamicComposite endScan = newComposite();
// add the discriminator value so we're querying for the specified class
// and it's children
startScan.addComponent(discriminatorValue, stringSerializer);
endScan.addComponent(discriminatorValue, stringSerializer);
int length = fields.length;
int last = length - 1;
int componentIndex = 1;
FieldExpression exp = null;
for (int i = 0; i < last; i++, componentIndex++) {
exp = query.getExpression(this.fields[i].getMetaData());
this.fields[i].addToComposite(
startScan, componentIndex, exp.getStart(), ComponentEquality.EQUAL);
this.fields[i].addToComposite(endScan, componentIndex, exp.getEnd(), ComponentEquality.EQUAL);
}
exp = query.getExpression(this.fields[last].getMetaData());
this.fields[last].addToComposite(
startScan, componentIndex, exp.getStart(), exp.getStartEquality());
this.fields[last].addToComposite(endScan, componentIndex, exp.getEnd(), exp.getEndEquality());
return new ScanBuffer(keyspace, startScan, endScan, indexName);
}
/**
* Get the index for the query
*
* @param query
* @return
*/
private AbstractIndexOperation getIndexOp(
IndexQuery query,
Value[] ordering,
boolean[] orderAscending,
CassandraClassMetaData metaData) {
Collection<FieldExpression> expFields = query.getExpressions();
FieldOrder[] fields = new FieldOrder[expFields.size()];
IndexOrder[] orders = new IndexOrder[ordering.length];
Iterator<FieldExpression> expFieldsItr = expFields.iterator();
// all fields are ascending by default in field equality.
for (int i = 0; i < fields.length; i++) {
FieldExpression current = expFieldsItr.next();
// if there's not start but an end then this column must be
// descending in
// the index
fields[i] = new FieldOrder(current.getField().getName(), true);
log.debug("in getIndexOp with field: {}", fields[i]);
}
for (int i = 0; i < orders.length; i++) {
orders[i] = new IndexOrder(((Path) ordering[i]).last().getName(), orderAscending[i]);
}
EntityFacade classMeta = conf.getMetaCache().getFacade(metaData, conf.getSerializer());
AbstractIndexOperation indexOp = classMeta.getIndexOperation(fields, orders);
if (indexOp == null) {
throw new UnsupportedException(
String.format(
"You attempted to query an index that does not exist. To perform this query you must define an index in the following format. '%s'",
getIndexExpression(fields, orders)));
}
return indexOp;
}