Optional Match returns null when node is present

Neo4j Graph Platform Cypher
1

version 4.1.1

I have a scenario where OPTIONAL MATCH does not work. I have two labels I am comparing where I want all items in the first label and the items that exist in the second label.

match (b:OldComponent) 
optional MATCH (n:Component {name: b.name}) 
RETURN b.name, n.name order by b.name;

Returns:

╒═══════════════════════════════════╤════════╕
│"b.name"                           │"n.name"│
╞═══════════════════════════════════╪════════╡
│"#2S15 RED"                        │null    │
├───────────────────────────────────┼────────┤
│"#6FO <2%"                         │null    │
├───────────────────────────────────┼────────┤
│"115 LATEX, TOTE, LB"              │null    │

If I remove the OPTIONAL I get:

╒════════════════╤═══════════════╕
│"b.name"                           │"n.name"                           │
╞════════════════╪════════════════╡
│"#2S15 RED"                        │"#2S15 RED"                        │
├────────────────┼─────────────────┤
│"#6FO <2%"                         │"#6FO <2%"                         │

As you can see from the result without the OPTIONAL the data does exist.

I have rebuilt the constraints/indexes but still the same results.

I tried to create a sample set of data in another database but could not recreate the issue.

Any ideas?

Sorry for the formatting. Couldn't figure out how to get it corrected.

2

Hi @higerdm , in the 2nd line "optional MATCH (n:Component {name: b.name}) ", the value of the name property should be n.name as per your requirements. Then it should fetch correct results

3

b.name is correct. I'm wanting to lookup the Component with the same name as the OldComponent. The only difference between the statements is the "optional" keyword.

FIrst Statement
match (b:OldComponent)
optional MATCH (n:Component {name: b.name})
RETURN b.name, n.name order by b.name;

Second Statement
match (b:OldComponent)
MATCH (n:Component {name: b.name})
RETURN b.name, n.name order by b.name;

4

This looks buggy.

Can you try prefixing your first query with CYPHER runtime=SLOTTED and see if it works?

If it still isn't working, please run a PROFILE on both queries, and export and attach the plans here so we can take a look