Python driver: execCypher() should quote-escape column aliases that are PostgreSQL reserved words

[uesleilima]

Describe the bug

The execCypher() function accepts a cols parameter that is used to build the AS (col1 agtype, col2 agtype, ...) clause in the generated SQL. The _validate_column() / validate_identifier() functions correctly validate that column names match ^[A-Za-z_][A-Za-z0-9_]*$, but they do not check whether the name is a PostgreSQL reserved word.

When a column alias happens to be a reserved word (e.g., count, sum, type, order, group, select), the generated SQL fails with a parse error because the alias is used unquoted in the AS (...) clause.

This is especially problematic when column aliases are derived from Cypher RETURN clauses (e.g., RETURN count(n) AS count).

How are you accessing AGE?

Python driver (psycopg3)

Steps to Reproduce

import age
import psycopg

conn = psycopg.connect("host=localhost dbname=postgres user=postgres",
                        cursor_factory=age.age.ClientCursor)
age.setUpAge(conn, "test_graph")

# This crashes because "count" is a PostgreSQL reserved word
cursor = age.execCypher(conn, "test_graph",
                        "MATCH (n:TestNode) RETURN count(n)",
                        cols=["count"])

Expected behavior

The query should succeed. The driver should quote-escape reserved-word column aliases in the generated AS (...) clause, e.g.:

SELECT * FROM cypher(NULL, NULL) AS ("count" agtype);

Actual behavior

PostgreSQL parse error because count is unquoted:

-- Generated SQL (broken):
SELECT * FROM cypher(NULL, NULL) AS (count agtype);
-- ERROR: syntax error at or near "count"

Current workaround

We maintain a list of 60+ PostgreSQL reserved words and prefix them with col_ before passing to execCypher():

_PG_RESERVED_WORDS = frozenset({"all", "and", "as", "count", "group", "order",
                                 "select", "sum", "type", "where", ...})

def _sanitize_alias(alias):
    if alias.lower() in _PG_RESERVED_WORDS:
        return f"col_{alias}"
    return alias

Suggested fix

In _validate_column() or buildCypher(), wrap column names in double quotes when they match PostgreSQL reserved words. PostgreSQL always accepts double-quoted identifiers, so quoting unconditionally (e.g., f'"{{name}}" {{type_name}}') would be the simplest and safest approach:

# In buildCypher() or _validate_column():
columnExp.append(f'"{{name}}" agtype')  # always quote — safe for all identifiers

Alternatively, use psycopg.sql.Identifier() which handles quoting automatically:

from psycopg import sql
# sql.Identifier(name) produces '"name"' only when needed

Environment

• Apache AGE: 1.5.0+ / master
• Python driver: master branch (psycopg3 version)
• psycopg: 3.2.x
• Python: 3.10+