Обсуждение: Set role dynamically from proc

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Set role dynamically from proc

От
Durumdara
Дата:
Hello!

May you know the way how to set role dynamically.

DO 
$$
DECLARE act_dbowner varchar(100);
BEGIN

SELECT u.usename into act_dbowner FROM pg_database d
JOIN pg_user u ON (d.datdba = u.usesysid)
WHERE d.datname = (SELECT current_database());
raise notice 'DB owner: %', act_dbowner;

set role to act_dbowner; --  THIS LINE
END
$$;

-------------

ERROR:  role "act_dbowner" does not exist
CONTEXT:  SQL statement "set role to act_dbowner"
PL/pgSQL function inline_code_block line 10 at SQL statement

I try to use $act_dbowner, but it have no effect.

Thank you for your help!

Best wishes
   dd

RE: Set role dynamically from proc

От
"Charles Clavadetscher"
Дата:

Hello

 

From: Durumdara [mailto:durumdara@gmail.com]
Sent: Mittwoch, 22. November 2017 14:56
To: pgsql-general@postgresql.org
Subject: Set role dynamically from proc

 

Hello!

 

May you know the way how to set role dynamically.

 

DO 

$$

DECLARE act_dbowner varchar(100);

BEGIN

 

            SELECT u.usename into act_dbowner FROM pg_database d

            JOIN pg_user u ON (d.datdba = u.usesysid)

            WHERE d.datname = (SELECT current_database());

            raise notice 'DB owner: %', act_dbowner;

 

            set role to act_dbowner; --  THIS LINE

           

END

$$;

 

-------------

 

ERROR:  role "act_dbowner" does not exist

CONTEXT:  SQL statement "set role to act_dbowner"

PL/pgSQL function inline_code_block line 10 at SQL statement

 

I try to use $act_dbowner, but it have no effect.

 

It seems that the user does not exist:

 

CREATE OR REPLACE FUNCTION set_role()

RETURNS VOID

AS $$

BEGIN

  RAISE NOTICE 'CURRENT_USER: %', (select current_user);

  SET ROLE blabla;

  RAISE NOTICE 'CURRENT_USER: %', (select current_user);

END;

$$ LANGUAGE plpgsql;

 

db=> select * from set_role();

NOTICE:  CURRENT_USER: kofadmin

ERROR:  role "blabla" does not exist

CONTEXT:  SQL statement "SET ROLE blabla"

PL/pgSQL function set_role() line 4 at SQL statement

 

db=> CREATE ROLE blabla;

CREATE ROLE

 

db=> select * from set_role();

NOTICE:  CURRENT_USER: kofadmin

ERROR:  permission denied to set role "blabla"

CONTEXT:  SQL statement "SET ROLE blabla"

PL/pgSQL function set_role() line 4 at SQL statement

 

db=> GRANT blabla TO kofadmin;

GRANT ROLE

 

Now it works:

 

db=> select * from set_role();

NOTICE:  CURRENT_USER: kofadmin

NOTICE:  CURRENT_USER: blabla

[...]

 

Regards

Charles

 

Thank you for your help!

 

Best wishes

   dd

Re: Set role dynamically from proc

От
Durumdara
Дата:
Hello!

I haven't got your mail, I see your answer only in the thread of web mailing list.

> It seems that the user does not exist:

The problem is based on that I want to set the role to the database owner from script.
My team members many times logged as "postgres" or diff user, and forget to set the role to DB owner.
I thought I can avoid the problems with changing the actual role to real owner before the changes.

Now the "set role" uses the "variable name", and not the "value of the variable".

This is what I don't like in this lang. I need to write a special variable name to "force" to use it, and not other thing.
I don't know how to force the system to use my variable value, and not my variable name in the routines.
For example $var$, or <var>, or [var], etc.

I can generate "set role" with string concat, but in PGAdmin this script would be good.

Thank you!
   dd





2017-11-22 14:55 GMT+01:00 Durumdara <durumdara@gmail.com>:
Hello!

May you know the way how to set role dynamically.

DO 
$$
DECLARE act_dbowner varchar(100);
BEGIN

SELECT u.usename into act_dbowner FROM pg_database d
JOIN pg_user u ON (d.datdba = u.usesysid)
WHERE d.datname = (SELECT current_database());
raise notice 'DB owner: %', act_dbowner;

set role to act_dbowner; --  THIS LINE
END
$$;

-------------

ERROR:  role "act_dbowner" does not exist
CONTEXT:  SQL statement "set role to act_dbowner"
PL/pgSQL function inline_code_block line 10 at SQL statement

I try to use $act_dbowner, but it have no effect.

Thank you for your help!

Best wishes
   dd

Re: Set role dynamically from proc

От
"David G. Johnston"
Дата:
On Wed, Nov 22, 2017 at 7:52 AM, Durumdara <durumdara@gmail.com> wrote:
Now the "set role" uses the "variable name", and not the "value of the variable".

This is what I don't like in this lang. I need to write a special variable name to "force" to use it, and not other thing.
I don't know how to force the system to use my variable value, and not my variable name in the routines.
For example $var$, or <var>, or [var], etc.

I can generate "set role" with string concat, but in PGAdmin this script would be good.


​There are three kinds of "words" in an SQL command: keywords, identifiers, ​values.

SET ROLE TO davidj;

SET := keyword
ROLE := keyword
TO := keyword
davidj := *identifier*

In pl/pgsql variables can only replace values, not identifiers or keywords.  Since the variable in this case holds an identifier you must use dynamic SQL to execute the statement you want.

not tested but basically:

EXECUTE format('SET ROLE %I', variablename); --(that's a percent-eye)

More generally when using "PREPARE" at the SQL-level only values can be replaced with placeholders ($1, $2, etc...).  All pl/pgsql is doing when you use a variable is writing out a PREPARE variation of your command and the executing it with the variable values as parameter values.

Identifiers are any words that the system is going to lookup in a catalog (I may be over-simplifying a bit, and the converse, values are not resolved in a catalog, is generally but possibly not always, true).  Identifiers can always be double-quoted to avoid their case-folding behavior.

David J.

Re: Set role dynamically from proc

От
Durumdara
Дата:
Dear David! To know - your solution is working well! *EXECUTE format('SET ROLE %I', variablename); * Thank you! bw dd