postgresql - 为什么只有 super 用户可以 CREATE EXTENSION hstore，而不能在 Heroku 上创建？

Question

当我尝试在我的数据库上启用 hstore 时:

=> CREATE EXTENSION IF NOT EXISTS hstore;
ERROR:  permission denied to create extension "hstore"
HINT:  Must be superuser to create this extension.

我的用户不是 super 用户，但是数据库的所有者。

根据 the CREATE EXTENSION docs :

Loading an extension requires the same privileges that would be required to create its component objects. For most extensions this means superuser or database owner privileges are needed. The user who runs CREATE EXTENSION becomes the owner of the extension for purposes of later privilege checks, as well as the owner of any objects created by the extension's script.

hstore 做什么需要 super 用户权限？它会影响我将其添加到的数据库之外的部分集群吗？

---

进一步的混淆:

The DB user Heroku Postgres provides is not a superuser :

Heroku Postgres users are granted all non-superuser permissions on their database. These include SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, TRIGGER, CREATE, CONNECT, TEMPORARY, EXECUTE, and USAGE.

然而，that user is able to CREATE EXTENSION hstore :

To create any supported extension, open a session with heroku pg:psql and run the appropriate command:

$ heroku pg:psql
Pager usage is off.
psql (9.2.4)
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
Type "help" for help.

ad27m1eao6kqb1=> CREATE EXTENSION hstore;
CREATE EXTENSION
ad27m1eao6kqb1=>

(对于上下文，我正在尝试设置一个 Dokku 部署，因此与 Heroku 的比较尤为重要。)

Answer 1

hstore 扩展创建从外部动态对象调用代码的函数，这需要 super 用户权限。这就是创建 hstore 扩展需要 super 用户权限的原因。

至于 Heroku，我的理解是他们运行着一个特殊的扩展白名单模块，允许用户创建某些扩展，即使他们不是 super 用户。我相信它基于以下代码:https://github.com/dimitri/pgextwlist .如果您想在数据库中使用相同的功能，您可以尝试自己安装该代码。