Re: [PATCH] Add pg_get_tablespace_ddl() function to reconstruct CREATE TABLESPACE statement

Hi Chao

On 19/11/2025 04:13, Chao Li wrote:
> 1. Do we need to perform some privilege check? I just did a test:
> ```
> evantest=> \c
> You are now connected to database "evantest" as user "evan".
> evantest=> select pg_get_tablespace_ddl('pg_default');
> pg_get_tablespace_ddl
> -------------------------------------------
> CREATE TABLESPACE pg_default OWNER chaol;
> (1 row)
> ```
>
> Where “evan” is a new user without grant any persuasion to it, but it can view the system default tablespace’s DDL. I don’t think that’s expected.

It is expected. \db behaves similarly:

CREATE TABLESPACE ts LOCATION '/tmp/ts';
CREATE TABLESPACE

postgres=# CREATE USER foo;
CREATE ROLE

postgres=# SET ROLE foo;
SET

postgres=> \db ts
List of tablespaces
Name | Owner | Location
------+-------+----------
ts | jim | /tmp/ts
(1 row)

IIUC the user foo is just reading the catalog entry of the new
tablespace, which is fine. Of course, accessing the tablespace itself is
not allowed. See \db+ (calculates the tablespace's size)

postgres=> \db+ ts
ERROR: permission denied for tablespace ts

Best, Jim