hi.
when i use a cypher query to get the queued nodes associated via
queue-relationships to a repository-node which has several million other
relationships then it takes about six minutes to fill that result list:
<pre>
List<Node> list = new ArrayList<Node>();
StringBuffer s = new StringBuffer();
s.append("START repository = (");
s.append((Long) controller.getRepositoryNode().getId());
s.append(") MATCH (repository)-[:");
s.append(Rels.REL_REPOSITORY_QUEUE);
s.append("]->(node) RETURN node ORDER BY node.");
s.append(Keys.KEY_TIMESTAMP);
s.append(" SKIP ");
s.append(Integer.toString(offset));
s.append(" LIMIT ");
s.append(Integer.toString(buffersize));
Log.log(s.toString());
Query query = this.parser.parse(s.toString());
ExecutionResult result = this.engine.execute(query);
Iterator<Node> iterator = result.columnAs("node");
while (iterator.hasNext()) {
list.add(iterator.next());
}
</pre>
but when i directly query the relationshipIndex containing all
queue-relationships and assuming that sorting by timestamp is equivalent
to sorting by node-ids then it completes in just half a minute, which is
a dozen times faster:
<pre>
List<Node> list = new ArrayList<Node>();
IndexHits<Relationship> hits =
controller.getRelationIndexRepositoryUrlQueue().query(
Keys.KEY_TYPE,Rels.REL_REPOSITORY_QUEUE,
controller.getRepositoryNode(),null
);
List<Long> ids = new ArrayList<Long>();
try {
for (Relationship hit : hits) {
ids.add(
hit.getEndNode().getId()
);
}
} finally {
hits.close();
}
Collections.sort(ids);
for (int i = offset; i < Math.min(offset + buffersize,ids.size()); i++) {
list.add(
this.graph.getNodeById(
ids.get(i)
)
);
}
</pre>
now my question. how can i efficiently get such a result list sorted for
some node property other than id. and question number two: how would a
cypher statement look like if it supported relationship-indices. maybe
<pre>
START x = (1)
MATCH (x)-[r:(MyRelationIndex,type,MyRelationType)]->(y)
RETURN r,y
ORDER BY y.somePropertyOtherThanId
</pre>
similar to nodeIndexLookups, where i give the name of the relationship
index to use, key and value for the relationship, start and end nodes
are given by (x) and (y) in this case. i'd like that feature very much
and if i knew how i'd probably even help to get on with it but anyway i
can be patient.
kindly, st.p.
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