Hello everyone,
I'm currently designing a cypher query which uses DISTINCT in combination
with aggregations and sorting and I'm not quite sure if I'm doing this the
right way.
My schema looks like this:
(user {userId: ..})-[rel:LOVES|HATES|IGNORES|... {timestamp:
..}]->(something {somethingId: .., additionalSortCriteria: ...})
I need a distinct list of Somethings, with only the newest relation of any
type, sorted by the additionalSortCriteria of Something.
I have for example:
(user {uid: 1})-[:LOVES {timestamp: "2013-01-01"}]->(something {sid:
1, additionalSortCriteria: 1})
(user {uid: 2})-[:LOVES {timestamp: "2013-02-01"}]->(something {sid:
1, additionalSortCriteria: 1})
(user {uid: 1})-[:LOVES {timestamp: "2013-03-01"}]->(something {sid:
2, additionalSortCriteria: 2})
...
I use this query:
MATCH (user:User)-[rel:LOVES]->(something:Something)
WITH DISTINCT(something.sid) as sid, MAX(rel.timestamp) AS timesort,
MAX(something.additionalSortCriteria) AS somethingsort ORDER BY
somethingsort, timesort
MATCH (user:User)-[rel:LOVES]->(something:Something) WHERE
something.sid=sid AND rel.timestamp=timesort AND
something.additionalSortCriteria=somethingsort
RETURN user,rel,something;
And get a list of user, relations, somethings with only distinct
somethings, sorted by the somethings.additionalSortCriteria criteria and
only the newest relation... it seems so at least.
The individual combinations of something.sid and relation.timestamps are
mostly unique, especially in combination with the additionalSortCriteria.
Did I get it right or have I overlooked something? Is there a better way to
do this?
Thank you!
Manuel
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