Unreliable Statistics#propertiesSet

[xujiaxj]

We are running a bunch of updating statements like this:

Statistics statistics = driver.query(graphId, query, params).getStatistics();
return statistics.propertiesSet();

The query variable is

MATCH (n:Service {site:$match_site, name:$match_name, namespace:$match_namespace, env:$match_env}) SET n.service_type=$service_type

and an example of the params variable is

{service_type=aurora-mysql, match_namespace=monitoring, match_site=dev, match_env=dev, match_name=aurora-mysql}

I assume if there is a match, the above code should return 1, and if there is no match, it should return 0.

Upon testing, I realize the return value is not reliable at all. Most of the time it returns 0 even though there is a match, so I wonder whether it only returns 1 if the update to service_type property actually changes the value. But then I noticed that in the cases it returns 1, there is a match but there is no change to the service_type property. In summary, neither 1 nor 0 means what I thought it is.

Can someone help explain?