Unexpected result of match statement with addition of string type

[czpmango]

test:

(czp@nebula) [nba]> match (v:player) where v.name+'n'=="Tim Duncann" return v
+---+
| v |
+---+
+---+
Empty set (time spent 18251/19363 us)

(czp@nebula) [nba]> return "Tim Duncan"+'n'
+--------------------+
| ("Tim Duncan"+"n") |
+--------------------+
| "Tim Duncann"      |
+--------------------+
Got 1 rows (time spent 1733/2835 us)

(czp@nebula) [nba]> match (v:player) where v.name-'n'=="Tim Dunca" return v
+-------------------------------------------------------------------------------------------------------------+
| v                                                                                                           |
+-------------------------------------------------------------------------------------------------------------+
| ("Tim Duncan" :bachelor{name: "Tim Duncan", speciality: "psychology"} :player{age: 42, name: "Tim Duncan"}) |
+-------------------------------------------------------------------------------------------------------------+
Got 1 rows (time spent 30993/32324 us)

The expected result is an error because the string type does not allow subtraction.

[Shylock-Hg]

What's the meaning of string subtraction? I think we should report Semantic Error or evaluate Null.

[cangfengzhs]

I guess when doing expression rewriting or expression folding, rewrite name+'n'=='Tim Ducann' to name='Tim Ducann'-'n', the latter is the calculation of string subtraction, Value does not support this calculation.

[czpmango]

What's the meaning of string subtraction? I think we should report Semantic Error or evaluate Null.

ACK.

[czpmango]

I guess when doing expression rewriting or expression folding, rewrite name+'n'=='Tim Ducann' to name='Tim Ducann'-'n', the latter is the calculation of string subtraction, Value does not support this calculation.

NCK. The subtraction of string type is invalid. We should modify the related index selection logic.

For match (v:player) where v.name+'n'=="Tim Duncann" return v, just do FullTagScan. The addition of string is just
runtime behavior of + expression.
For match (v:player) where v.name-'n'=="Tim Dunca" return v, throw a Semantic error.

[CPWstatic]

I looks fine to me, maybe i don't figure out what you are trying to tell.

v.name+'n'=="TIm Duncann"
equal to ?
v.name=="Tim Duncann"-'n'

v.name-'n'=="Tim Dunca"
euqal to ?
v.name=="Tim Dunca"+'n'

[czpmango]

I looks fine to me, maybe i don't figure out what you are trying to tell.

v.name+'n'=="TIm Duncann"
equal to ?
v.name=="Tim Duncann"-'n'

v.name-'n'=="Tim Dunca"
euqal to ?
v.name=="Tim Dunca"+'n'

Just like implementation of std::string, which supports only addition(operator+/operator+=) but not subtraction(operator-) operations.
Indeed, as you say, "Tim Duncan" - 'n' and "Tim Dunca" are equivalent. You can define any addition but can not necessarily define subtraction such as "Tim Duncan" - 'a'.

[czpmango]

I guess when doing expression rewriting or expression folding, rewrite name+'n'=='Tim Ducann' to name='Tim Ducann'-'n', the latter is the calculation of string subtraction, Value does not support this calculation.

NCK. The subtraction of string type is invalid. We should modify the related index selection logic.

For match (v:player) where v.name+'n'=="Tim Duncann" return v, just do FullTagScan. The addition of string is just runtime behavior of + expression. For match (v:player) where v.name-'n'=="Tim Dunca" return v, throw a Semantic error.

Fwiw, that is only the testing behavior of Neo4j, which is not specified by cypher standard.