OPTIONAL MATCH

[Marwa Elabri]

Hello

please are there another clause that replace optional match in cypher query language 

because I want to get null value from my neo4j database but when I use optional mach with a huge database the request execution takes a lot of time ????

Thank you in advance 

[Eve Freeman]

Without a query it’s hard to help you on this... 

Often, I tell people to start with a match of what you know exists, and then do an optional match for what you’re not sure exists, like:

match (p:Person) // we want to get all Person nodes 

optional match (p)-[:FOLLOWS]->(maybe:Person)

return p.name, maybe.name

This way, you give the engine some help with the starting point. Does this help?

Eve

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[Marwa Elabri]

I have two kind of query 

the first one I start from a node such as 

match (n:student)

optional math (n)-[R:takes]-(n2:course)

return n, n2

The second kind of request: I have to start (point) from a relationship such as:

match ()-[R:takes]-()

optional match  ()-[R:takes]-(n:student)

optional match  (n:student)-[R:takes]-(p:course)

return n,p

but when I make this kind of query specially if I point to a relationship it takes a looooot of time :( so can I find another solution how to improve this type of query (with optional much)

thank for your help

[Eve Freeman]

In this case why do you need to start on the relationship? Can you start with student + relationship instead?

Can you explain in English what you’re trying to ask of be database?

Eve