Silence6666668 opened a new issue, #2392:
URL: https://github.com/apache/age/issues/2392
**Describe the bug**
List slicing may return a concrete sublist on Apache AGE when either the
slice start bound or end bound is `null`.
For example, in the minimized repro below, `[1,2,3][1..null]` should
evaluate to `null` under Cypher null-propagation semantics. Instead, AGE treats
the `null` bound like an omitted bound and returns `[2, 3]`.
The same issue appears symmetrically for a `null` start bound.
**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?**
```pgsql
SELECT create_graph('expr_slice_bug');
```
No graph data is required beyond creating an empty 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: `expr_slice_bug`
- No extra extensions or special configuration were required
**What is the command that caused the error?**
```pgsql
SELECT * FROM cypher('expr_slice_bug', $$
RETURN [1, 2, 3][1..null] AS v
$$) AS (v agtype);
```
Returned result on AGE:
```text
[2, 3]
```
**Expected behavior**
The query should return:
```text
null
```
Both Neo4j and Memgraph return `null` for the equivalent Cypher query.
**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**
The symmetric variant with a `null` start bound shows the same issue:
```pgsql
SELECT * FROM cypher('expr_slice_bug', $$
RETURN [1, 2, 3][null..2] AS v
$$) AS (v agtype);
```
Expected result on Neo4j and Memgraph:
```text
null
```
Observed result on AGE:
```text
[1, 2]
```
A normal non-null slice behaves as expected on the same AGE instance:
```pgsql
SELECT * FROM cypher('expr_slice_bug', $$
RETURN [1, 2, 3][1..2] AS v
$$) AS (v agtype);
```
Observed result on AGE:
```text
[2]
```
There is also an internal inconsistency when both bounds are `null`:
```pgsql
SELECT * FROM cypher('expr_slice_bug', $$
RETURN [1, 2, 3][null..null] AS v
$$) AS (v agtype);
```
Neo4j and Memgraph both return:
```text
null
```
But AGE reports:
```text
ERROR: slice start and/or end is required
```
So AGE appears to treat `null` slice bounds inconsistently:
- one `null` bound is interpreted like an omitted boundary
- two `null` bounds trigger an error
Neither behavior matches the `null` result returned by Neo4j and Memgraph.
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