cursor = conn.cursor(name="fetch_news_for_migration")
cursor.itersize = 5000
cursor.execute(...)
rows = cursor.fetchall()  # ← carrega tudo em memória de qualquer forma

def _execute_with_history(
    conn,
    migration: MigrationInfo,
    operation: str,
    dry_run: bool,
    applied_by: str,
    run_id: str | None,
    action_fn,  # callable(conn) -> (description, execution_details)
):
    """Execute an action (migrate or rollback) with atomic history recording."""
    effective_op = "dry_run" if (dry_run and operation == "migrate") else operation
    started_at = time.time()

    logger.info(
        f"{'[DRY RUN] ' if dry_run else ''}"
        f"{'Rolling back' if operation == 'rollback' else 'Executing'} "
        f"{migration.version}_{migration.name} ({migration.migration_type})"
    )

    try:
        description, execution_details = action_fn(conn)

        if dry_run:
            _record_history(
                conn, migration, effective_op, "success", started_at,
                applied_by, run_id, description, execution_details,
            )
            conn.rollback()
            logger.info(f"[DRY RUN] {migration.version} previewed (rolled back)")
        else:
            _record_history(
                conn, migration, effective_op, "success", started_at,
                applied_by, run_id, description, execution_details,
            )
            conn.commit()
            logger.info(f"{migration.version}_{migration.name} {operation}d successfully")

    except Exception as e:
        conn.rollback()
        try:
            _record_history(
                conn, migration, effective_op, "failed", started_at,
                applied_by, run_id, error_message=str(e),
            )
            conn.commit()
        except Exception:
            logger.warning(f"Could not record {operation} failure in migration_history")
        raise

def execute_migration(conn, migration, dry_run, applied_by, run_id):
    def action(conn):
        if migration.migration_type == "sql":
            cursor = conn.cursor()
            try:
                cursor.execute(migration.path.read_text())
            finally:
                cursor.close()
            return None, None
        else:
            module = _load_python_module(migration.path)
            if not hasattr(module, "describe"):
                raise AttributeError(f"Python migration {migration.path.name} must define describe()")
            description = module.describe()
            result = module.migrate(conn, dry_run=dry_run)
            return description, result if isinstance(result, dict) else None

    _execute_with_history(conn, migration, "migrate", dry_run, applied_by, run_id, action)


def execute_rollback(conn, migration, dry_run, applied_by, run_id):
    def action(conn):
        if migration.migration_type == "sql":
            if not migration.rollback_path or not migration.rollback_path.exists():
                raise FileNotFoundError(
                    f"No rollback file for SQL migration {migration.version}_{migration.name}"
                )
            cursor = conn.cursor()
            try:
                cursor.execute(migration.rollback_path.read_text())
            finally:
                cursor.close()
            return None, None
        else:
            module = _load_python_module(migration.path)
            result = module.rollback(conn, dry_run=dry_run)
            return None, result if isinstance(result, dict) else None

    _execute_with_history(conn, migration, "rollback", dry_run, applied_by, run_id, action)