Different results when counting * and c

[Guy Korland]

ref: RedisGraph/RedisGraph#3214

I execute two queries on my empty RedisGraph and get an error.

Redis version:7.2.0
RedisGraph version: v2.12.10
operating system: windows 11
API：Cypher version 9

To reproduce:

OPTIONAL MATCH (c)-[:PP]-() WHERE c IS NOT NULL RETURN count(*)
OPTIONAL MATCH (c)-[:PP]-() WHERE c IS NOT NULL RETURN count(c)

Actual behavior:
When counting by *,the result is 1 but when counting by c the result becomes 0.
I'm asking if this is an expected result or a bug?

[Avi Avni]

this is the same result as in the latest neo4j 5.13.0

when counting the 'c' variables null values are not counted
when counting the '*' any record counted
even that you have the where that filter null values it is under the OPTIONAL MATCH so if there is no pattern that meets the filter c will be null for 1 record

[Guy Korland]

@ljhhuxiaoba

[ljhhuxiaoba]

Thanks for you explanation!