如何从Neo4j Cypher搜索结果中排除连接到特定节点的节点

Question

I need to perform a Neo4J Cypher query where I exclude the nodes from the result that are connected to a specific node.

I'm using that query below, but it's very slow (several seconds).

What I do below is to first get the node (of the Context type), which the other nodes should not be connected to.

Then I make the next query, finding the nodes, created by the same user but in another context " help " and exclude those of them that are also connected to the " private " context.

MATCH (u:User{uid:'6dbe5450-852d-11e4-9c48-b552fc8c2b90'}), 
(ctxa:Context{name:"private"}), ctxa-[:BY]->u 
WITH ctxa,u MATCH (s:Statement), (ctx:Context{name:"help"}), ctx-[:BY]->u, 
s-[:IN]->ctx, s-[:BY]->u 
WHERE NOT s-[:IN]->ctxa 
RETURN DISTINCT s.uid ORDER BY s.timestamp DESC;

Anyone has a better idea?

UPDATE: I also tried this:

MATCH (u:User{uid:'b9745f70-a13f-11e3-98c5-476729c16049'}), (s:Statement), 
(ctx:Context{name:"private"}), ctx-[:BY]->u, s-[:IN]->ctx, s-[:BY]->u 
WITH s AS sta, u MATCH (s:Statement), (ctx:Context{name:"help"}), 
ctx-[:BY]->u, s-[:IN]->ctx, s-[rel:BY]->u WHERE s <> sta RETURN DISTINCT s; 

Answer 1

Found that that using DISTINCT in the query really improved the speed:

MATCH (u:User{uid:'b9745f70-a13f-11e3-98c5-476729c16049'}), 
(ctxa:Context{name:"private"}), ctxa-[:BY]->u 
WITH DISTINCT ctxa,u 
MATCH (s:Statement), s-[rel:BY]->u, (ctx:Context{name:"bodypractices"}), 
ctx-[:BY]->u, s-[:IN]->ctx  
WHERE NOT s-[:IN]->ctxa 
RETURN DISTINCT s;

Basically the problem was that I was not using DISTINCT with the first WITH clause and because of the structure of my database (or maybe for another reason) I was getting a lot of rows for ctxa and then each was checked in the WHERE statement, slowing everything down.