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neo4jcypher

How do I do multiple OPTIONAL MATCH in parallel in Cypher?

I am currently doing something like:

MATCH (s:Something)
OPTIONAL MATCH (t:Tag)<-[:HAS_TAG]-(s)
OPTIONAL MATCH (i:Item)<-[:HAS_ITEM]-(s)
OPTIONAL MATCH (w:Whatever)<-[:HAS_WHATEVER]-(s)

When I do a profile, I see that 3 optional expand for each OPTIONAL MATCH sequentially, wonder if I can speed it up by possibly doing it in parallel? Since its independent of each other?

Solution

  • in these cases I often do

    MATCH (s:Something)
WITH s,
     [(s)-[:HAS_TAG]->(t:Tag) | t] AS ts,
     [(s)-[:HAS_ITEM]->(i:Item) | i] AS is,
     [(s)-[:HAS_TAG]->(w:Whatever) | w] AS ws

    which returns arrays, instead of null in case the OPTIONAL MATCH does not return anything. and often it's faster too.