Re: [GENERAL] Row level security policy - calling function for righthand side value of 'in' in using_expression - Mailing list pgsql-general

From Jong-won Choi
Subject Re: [GENERAL] Row level security policy - calling function for righthand side value of 'in' in using_expression
Date
Msg-id 1eac8426-3348-b54c-2725-b1af156d71b2@ticketsquad.com
Whole thread Raw
In response to Re: [GENERAL] Row level security policy - calling function for right hand side value of 'in' in using_expression  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Thanks Tom!

I actually considered what you suggested earlier, but somehow I thought
the function get called as many as number of rows, then guessed
returning a list might be cached and used internally (but I confess that
I do not know the internals of RLS).


Anyway, I rewrote it as you suggested:

        CREATE OR REPLACE FUNCTION valid_promoter_p(promoter_id BIGINT)
RETURNS BOOLEAN
          LANGUAGE plpgsql
        AS $$
           DECLARE
                ts_promoter_id BIGINT =
substring(current_setting('ts.promoter',TRUE),26)::BIGINT;
           BEGIN
                RETURN ((promoter_id = ts_promoter_id) AND
                        NOT EXISTS(SELECT TRUE FROM Agency WHERE
Agency.promoter = ts_promoter_id))
                       OR
                       EXISTS(SELECT TRUE FROM Agency WHERE
Agency.promoter = ts_promoter_id AND promoter_id = ANY(customers));
           END
        $$;



Have a great weekend!

- Jong-won

On 03/02/17 17:14, Tom Lane wrote:
> Jong-won Choi <jongwon@ticketsquad.com> writes:
>> I have a RLS policy definition like:
>>          CREATE POLICY promoter_policy ON Agency
>>          USING (promoter in build_valid_promoter_list())
>>          WITH CHECK (promoter in build_valid_promoter_list());
> That's failing basic SQL expression syntax: the RHS of "IN" has
> to be a parenthesized sub-select or array value.  You'd have better
> luck with (promoter in (select * from build_valid_promoter_list()))
> ... syntax-wise, at least.  I'm not sure if we allow sub-selects
> in RLS conditions.
>
> Personally I'd write that more like
>     USING (check_valid_promoter(promoter))
> with that function being defined in the obvious way.  There's little
> reason to enumerate the entire set of valid promoters if you only
> need to find out whether one specific value is one.
>
>             regards, tom lane



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