Neo4j Query Performance tuning Undestanding

Question

I am trying to optimize the query performance in my Neo4j. I have created the Unique indexes and the query is performing pretty good. But the query performance figure shown in the Neo4j web console shows as "0 estimated rows" and "0 db hits".

But in real, I am getting the result with one relationship.

My query:

Match (a:Person{id:"1234"})-[r:Employed_by]->(b:Organization(id:"abcd")) RETURN r

This query returns me a relationship.

But when I am checking the same query with Profile, it is showing like "0 estimated rows" and "0 db hits".

What does this mean? Please elaborate the result.

Answer 1

The number of estimated rows is only a rough estimate used to guide the cost planner before the query is executed; it will frequently not exactly match the actual number of rows obtained by an operation.

An operation's number of db hits will be zero if there is no need to access any data from the DB to perform the operation (i.e., if all the data needed by the operation is already available in memory).