Best practices for queries that can take hours to complete

Neo4j Graph Platform Cypher
3

see the very good video:

which also points to:

Not knowing specifics of your problem, here are some random ideas (stabs in the dark and I don't mean to insult your intelligence if you already know about these...):

  • Make sure you have indexes created for things that you are filtering on. Also potentially useful is composite indexes: Composite Indexes in Neo4j 4.0 | Max De Marzi
  • Use integers or floats where possible (e.g. toInteger() and toFloat() and store them in the DB before doing the query)
  • Avoid cartesian products: Instead of MATCH(a:A),(b:B) WHERE ... use MATCH(a:A) MATCH(b:B) WHERE...
  • Use Labels in your queries. MATCH(a)-[r]-> ... is more expensive than MATCH(a:A)-[r:R]->...
  • Try parallelism: Parallel Cypher Execution - APOC Extended Documentation (I haven't tried it myself, so I'm not sure how it works exactly.)
  • figure out how to winnow down the possible matches as much as possible and as soon as possible in the query.
  • I suspect this is true: take advantage of NULL values instead of setting things to empty strings or 0. I believe that property looks will go faster if Neo4J sees that there is no property, instead of looking up the property and then getting its value to do the comparison. E.g. length(a.property)=0 is more expensive than a.property IS NULL but I don't know how much more expensive it is.

I hope this helps. If you could show us your query (along with some statistics: call apoc.meta.stats and :schema) perhaps we could better be able to help you.

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