使用sqlalchemy.sql.text（）时找不到sqlalchemy命名游标

Question

运行良好：

with conn.connection.cursor(name='migration_cursor') as ss_cur:
    ss_cur.execute("SELECT id, stuff FROM cart WHERE stuff_type={}".format(some_variable))

然而，这失败了：

from sqlalchemy.sql import text
with conn.connection.cursor(name='migration_cursor') as ss_cur:
    ss_cur.execute(text("SELECT id, stuff FROM cart WHERE stuff_type=:some_variable"), some_variable=some_variable)

出现此错误消息：

psycopg2.OperationalError: cursor "migration_cursor" does not exist