Add generated SQL columns for graph properties

AGE keeps all properties in one agtype column and its Cypher writes fire
no triggers, so the bridge periodically calls a stored procedure that adds
a stored generated text column for every new property key. Only label
tables with inserts or updates since the previous run are scanned.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/smoke_test.py

@@ -4,9 +4,13 @@
 
 Usage: python tests/smoke_test.py [bolt-uri] [user] [password]
 Requires: pip install neo4j
+Set PEO4C_SMOKE_PG_DSN (e.g. "host=localhost dbname=postgres") to also check the
+generated property columns over SQL; that needs psycopg.
 """
 
+import os
 import sys
+import time
 
 import neo4j
 from neo4j.graph import Node, Path, Relationship
@@ -117,6 +121,22 @@ MATCH ()-[]->() RETURN { name:'relationships', data: count(*)} AS result
 
         check("managed write transaction", s.execute_write(work) == 1)
 
+    dsn = os.environ.get("PEO4C_SMOKE_PG_DSN")
+    if dsn:
+        import psycopg
+
+        with psycopg.connect(dsn, user=user, password=password, autocommit=True) as pg:
+            query = f'SELECT name, age FROM "{GRAPH}"."Person" ORDER BY name'
+            for _ in range(30):
+                try:
+                    rows = pg.execute(query).fetchall()
+                    break
+                except psycopg.errors.UndefinedColumn:
+                    time.sleep(0.5)
+            else:
+                rows = None
+            check("generated property columns", rows == [("Ann", "30"), ("Bob's", None)])
+
     with driver.session(database="system") as s:
         s.run(f"DROP DATABASE {GRAPH}").consume()