hkjiang26 opened a new issue, #2518:
URL: https://github.com/apache/age/issues/2518
## Bug description
Putting a `reduce()` expression — or a list comprehension — inside a `LIMIT`
or `SKIP` clause makes AGE 1.8.0 fail with the internal error `ERROR: 0A000:
unsupported SubLink`. The query has no subquery and no outer variable; the
trigger is the `reduce`'s own list iteration variable (`b IN [0]`). Neo4j runs
the same statement normally.
## Access method
- Command line via `psql`, inside the official Docker container
`apache/age:1.8.0`
## Data setup
No data is required — the error reproduces on an empty graph. Only the graph
itself must exist:
```pgsql
CREATE EXTENSION IF NOT EXISTS age;
LOAD 'age';
SET search_path = ag_catalog, "$user", public;
SELECT create_graph('graph_test');
```
## Configuration
- None beyond the stock AGE extension. No additional modules (no PostGIS,
etc.), default `search_path` handling as shown above.
## Command that triggers the error
```pgsql
SELECT * FROM cypher('graph_test', $$ RETURN 1 LIMIT reduce(a = 1, b IN [0]
| a + b) $$) AS (c0 agtype);
```
```
ERROR: unsupported SubLink
```
(SQLSTATE `0A000`, internal error.) Run the statement on its own (e.g. `psql
-c "..."`): when several statements are piped to `psql` at once, stdout/stderr
buffering can push the `ERROR` line to a different position in the output and
make it look like the query succeeded.
The failure is specific to `LIMIT`/`SKIP`: the same `reduce` returns a row
without one, and `LIMIT` accepts other data-free expressions:
```pgsql
-- works: reduce without LIMIT
SELECT * FROM cypher('graph_test', $$ RETURN reduce(a = 1, b IN [0] | a + b)
$$) AS (c0 agtype);
-- works: arithmetic / function in LIMIT
SELECT * FROM cypher('graph_test', $$ RETURN 1 LIMIT 1 + 1 $$) AS (c0
agtype);
SELECT * FROM cypher('graph_test', $$ RETURN 1 LIMIT size([0, 0]) $$) AS (c0
agtype);
```
## Environment
- Version: 1.8.0 (official `apache/age:1.8.0` Docker image)
- PostgreSQL: 18.1 (Debian 18.1-1.pgdg13+2), x86_64
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