Re: Postgres_fdw- User Mapping with md5-hashed password

On 4/8/25 13:00, Dirschel, Steve wrote:
> I know I can create user steve_test with password testpassword122 as md5 by doing:
>
> select 'md5'||md5('testpassword122steve_test'); Returns --> md5eb7e220574bf85096ee99370ad67cbd3
>
> CREATE USER steve_test WITH PASSWORD 'md5eb7e220574bf85096ee99370ad67cbd3';
>
> And then I can login as steve_test with password testpassword122.
>
> I'm trying to use similar logic when creating a user mapping:
>
> CREATE USER MAPPING FOR postgres SERVER steve_snap0 OPTIONS (user 'steve_test', password 'md5eb7e220574bf85096ee99370ad67cbd3');
>
> When I try and import a foreign schema I get an error:
>
> ERROR: could not connect to server "steve_snap0"
>
> If I create the user mapping with the password:
>
> CREATE USER MAPPING FOR postgres SERVER steve_snap0 OPTIONS (user 'steve_test', password 'testpassword122');
>
> It works fine.
>
> Is it not possible to use the same logic for the user mapping password that can be used when creating a user?

A) Short version

No you can't.

b) Long version

From here:

CREATE ROLE

https://www.postgresql.org/docs/current/sql-createrole.html

"If the presented password string is already in MD5-encrypted or
SCRAM-encrypted format, then it is stored as-is regardless of
password_encryption (since the system cannot decrypt the specified
encrypted password string, to encrypt it in a different format). This
allows reloading of encrypted passwords during dump/restore."

Whereas from here:

https://www.postgresql.org/docs/current/postgres-fdw.html

" user mapping, defined with CREATE USER MAPPING, is needed as well to
identify the role that will be used on the remote server:

CREATE USER MAPPING FOR local_user
SERVER foreign_server
OPTIONS (user 'foreign_user', password 'password');
"

In the above you are just supplying values to the connection string not
actually creating a password as in the first case.

>
> Thanks in advance.
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--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com