public Iterator<PartitionLocator> locatorScan(
final AbstractScaleOutFederation<?> fed, final IPredicate<?> predicate) {
final long timestamp = getReadTimestamp();
// Note: assumes that we are NOT using a view of two relations.
final IRelation<?> relation =
(IRelation<?>) fed.getResourceLocator().locate(predicate.getOnlyRelationName(), timestamp);
/*
* Find the best access path for the predicate for that relation.
*
* Note: All we really want is the [fromKey] and [toKey] for that
* predicate and index. This MUST NOT layer on expanders since the
* layering also hides the [fromKey] and [toKey].
*/
@SuppressWarnings("unchecked")
final AccessPath<?> accessPath = (AccessPath<?>) relation.getAccessPath((IPredicate) predicate);
// Note: assumes scale-out (EDS or JDS).
final IClientIndex ndx = (IClientIndex) accessPath.getIndex();
/*
* Note: could also be formed from relationName + "." +
* keyOrder.getIndexName(), which is cheaper unless the index metadata
* is cached.
*/
final String name = ndx.getIndexMetadata().getName();
return fed.locatorScan(
name, timestamp, accessPath.getFromKey(), accessPath.getToKey(), false /* reverse */);
}
public IAccessPath getTailAccessPath(final IRelation relation, final IPredicate predicate) {
return relation.getAccessPath(
indexManager /* localIndexManager */, relation.getKeyOrder(predicate), predicate);
// if (predicate.getPartitionId() != -1) {
//
// /*
// * Note: This handles a read against a local index partition. For
// * scale-out, the [indexManager] will be the data service's local
// * index manager.
// *
// * Note: Expanders ARE NOT applied in this code path. Expanders
// * require a total view of the relation, which is not available
// * during scale-out pipeline joins. Likewise, the [backchain]
// * property will be ignored since it is handled by an expander.
// */
//
// return ((AbstractRelation<?>) relation)
// .getAccessPathForIndexPartition(indexManager, predicate);
//
// }
//
// // Find the best access path for the predicate for that relation.
// final IAccessPath<?> accessPath = relation.getAccessPath(predicate);
//
// // Note: No expander's for bops, at least not right now.
//// final ISolutionExpander expander = predicate.getSolutionExpander();
////
//// if (expander != null) {
////
//// // allow the predicate to wrap the access path
//// accessPath = expander.getAccessPath(accessPath);
////
//// }
//
// // return that access path.
// return accessPath;
}