fix: serialize schema init for postgres

packages/adapters/sqlalchemy_impl/session.py

@@ -1,11 +1,15 @@
 from __future__ import annotations
 
-from sqlalchemy import create_engine
-from sqlalchemy.orm import Session, sessionmaker
+from sqlalchemy import create_engine, text
+from sqlalchemy.engine import URL, make_url
+from sqlalchemy.orm import sessionmaker
 
 from packages.adapters.sqlalchemy_impl.models import Base
 
 
+SCHEMA_INIT_LOCK_ID = 2026061501
+
+
 def build_engine(
     database_url: str,
     *,
@@ -42,5 +46,33 @@ def build_session_factory(
     return engine, session_factory
 
 
+def _build_admin_url(database_url: str) -> URL:
+    url = make_url(database_url)
+    return url.set(database="postgres")
+
+
+def ensure_database_exists(database_url: str) -> None:
+    target_url = make_url(database_url)
+    admin_engine = create_engine(_build_admin_url(database_url), isolation_level="AUTOCOMMIT")
+    try:
+        with admin_engine.connect() as connection:
+            exists = connection.execute(
+                text("SELECT 1 FROM pg_database WHERE datname = :database_name"),
+                {"database_name": target_url.database},
+            ).scalar()
+            if exists:
+                return
+            connection.execute(text(f'CREATE DATABASE "{target_url.database}"'))
+    finally:
+        admin_engine.dispose()
+
+
 def initialize_database(engine) -> None:
-    Base.metadata.create_all(bind=engine)
+    with engine.connect() as connection:
+        connection.execute(text("SELECT pg_advisory_lock(:lock_id)"), {"lock_id": SCHEMA_INIT_LOCK_ID})
+        try:
+            Base.metadata.create_all(bind=connection)
+            connection.commit()
+        finally:
+            connection.execute(text("SELECT pg_advisory_unlock(:lock_id)"), {"lock_id": SCHEMA_INIT_LOCK_ID})
+            connection.commit()