hkjiang26 opened a new issue, #2568:
URL: https://github.com/apache/age/issues/2568
**AGE Version:** extension 1.8.0 on PostgreSQL 18.6
**Installation Method:** Docker
**API:** Cypher and direct SQL
## Steps to reproduce (paste into psql as-is)
```sql
LOAD 'age';
SET search_path = ag_catalog, public;
-- Cypher path (re-run: DROP GRAPH xdb CASCADE first)
SELECT * FROM create_graph('xdb');
SELECT * FROM cypher('xdb', $$ RETURN split('a.b.c', '.') $$) AS (r agtype);
-- SQL path (same C function, no graph needed)
SELECT age_split('a.b.c', '.'); -- -> ["", "", "", "", "", ""]
SELECT age_split('a1b1c', '1'); -- -> ["a", "b", "c"] (plain
delimiter: works)
SELECT age_replace('a.b.c', '.', '-'); -- -> "a-b-c"
SELECT age_split('a.b.c', '\.'); -- -> ["a", "b", "c"] (only because
it is regex-escaped)
SELECT age_split('a|b', '|'); -- -> ["a", "|", "b"]
SELECT age_split('a+b+c', '+'); -- -> ERROR: invalid regular
expression: quantifier operand invalid
```
## Expected behavior
openCypher defines the split delimiter as a **literal string**:
`split('a.b.c', '.')` → `['a','b','c']`. Neo4j, Memgraph and FalkorDB all
return this without any escaping, and `replace('a.b.c', '.', '-')` → `'a-b-c'`
in AGE too — so both functions must interpret '.' identically.
## Actual behavior
- `split('a.b.c', '.')` → `["","","","","",""]` (six empty strings): the
delimiter is compiled as a **regular expression**, so '.' matches every
character.
- `split('a1b1c', '1')` → `["a","b","c"]`: plain delimiters work, so the
regex interpretation only surfaces for metacharacters — exactly where queries
silently break.
- `split('a.b.c', '\.')` → `["a","b","c"]`: correct **only** because the
user manually regex-escapes the dot.
- `split('a|b', '|')` → `["a","|","b"]`: the empty-alternation regex splits
at every position.
- `split('a+b+c', '+')` → `ERROR: invalid regular expression: quantifier
operand invalid`.
- `replace('a.b.c', '.', '-')` → `"a-b-c"`: the same engine treats the same
delimiter literally.
The engine is internally inconsistent, deviates from openCypher and all
sibling engines, and silently corrupts results for common literal delimiters
('.', '|', '+', ...).
## Root cause
`age_split()` (src/backend/utils/adt/agtype.c) passes the delimiter verbatim
to PostgreSQL's `regexp_split_to_array()`, which compiles it as a regular
expression; `age_replace()` performs a literal replacement. Cypher
`split()`/`replace()` are rewritten to these same SQL functions, so both APIs
are affected.
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