Silence6666668 opened a new issue, #2391:
URL: https://github.com/apache/age/issues/2391
**Describe the bug**
Map literals may drop keys whose values are `null`.
In Cypher, a map literal like `{a: null}` should still contain the key `a`
with a null value. Instead, Apache AGE returns an empty map `{}`.
This also affects larger queries that build maps from optional matches: when
all projected values are null, AGE returns `{}` instead of preserving the keys
with null values.
**How are you accessing AGE (Command line, driver, etc.)?**
- PostgreSQL `cypher(...)` wrapper through the local Python
differential-testing harness
- Reproducible directly in `psql` inside the Docker container
**What data setup do we need to do?**
No graph data is required for the minimal repro beyond creating an empty
graph:
```pgsql
SELECT create_graph('fuzz_graph');
```
**What is the necessary configuration info needed?**
- Plain Apache AGE Docker image was enough
- Docker image in local repro: `apache/age`
- AGE extension version: `1.7.0`
- PostgreSQL version: `18.1`
- Graph name used in repro: `fuzz_graph`
- No extra extensions or special configuration were required
**What is the command that caused the error?**
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
RETURN {a: null} AS m
$$) AS (m agtype);
```
Returned result on AGE:
```text
{}
```
**Expected behavior**
The returned map should preserve the key:
```text
{a: null}
```
Neo4j returns a map containing the key with a null value for the equivalent
Cypher query:
```cypher
RETURN {a: null} AS m
```
**Environment (please complete the following information):**
- Version: Apache AGE `1.7.0`
- PostgreSQL: `18.1`
- Host OS: Windows
- Architecture: x86_64
- Deployment: Docker
**Additional context**
A two-key control case shows the same behavior:
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
RETURN {companyName: null, sinceYear: null} AS m
$$) AS (m agtype);
```
AGE returns:
```text
{}
```
Expected result:
```text
{companyName: null, sinceYear: null}
```
Two additional expressions suggest this is a semantic loss of null-valued
map entries, not just a display issue for one literal form.
1. `keys({a: null})`:
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
RETURN keys({a: null}) AS ks
$$) AS (ks agtype);
```
Expected result on Neo4j and Memgraph:
```text
["a"]
```
Observed result on AGE:
```text
[]
```
2. `coalesce({a: null}, null)`:
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
RETURN coalesce({a: null}, null) AS m
$$) AS (m agtype);
```
Expected result on Neo4j and Memgraph:
```text
{a: null}
```
Observed result on AGE:
```text
{}
```
This also showed up during automated Neo4j-vs-AGE differential testing in a
larger query using `OPTIONAL MATCH` and `collect(...)`:
```cypher
MATCH (employee:Person)
OPTIONAL MATCH (employee)-[r:WORKS_FOR]->(company)
WHERE r.since > 2020
WITH employee, collect({companyName: company.name, sinceYear: r.since}) AS
workHistory
WHERE size(workHistory) > 0
RETURN employee.name AS name, COUNT { (employee)-[:WORKS_FOR]->() } AS
jobCount, workHistory
ORDER BY jobCount DESC
```
For rows where `company.name` and `r.since` were both null, Neo4j returned:
```text
[{companyName: null, sinceYear: null}]
```
while AGE returned:
```text
[{}]
```
That suggests the issue is not just display formatting of a top-level
literal, but a semantic loss of null-valued map entries during Cypher
evaluation.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
