Re: proposal: schema variables

2017-11-02 13:35 GMT+01:00 Robert Haas <robertmhaas(at)gmail(dot)com>:

> On Thu, Oct 26, 2017 at 12:51 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> wrote:
> > The variables can be modified by SQL command SET (this is taken from
> > standard, and it natural)
> >
> > SET varname = expression;
>
> Overloading SET to handle both variables and GUCs seems likely to
> create problems, possibly including security problems. For example,
> maybe a security-definer function could leave behind variables to
> trick the calling code into failing to set GUCs that it intended to
> set. Or maybe creating a variable at the wrong time will just break
> things randomly.
>

The syntax CREATE OR REPLACE FUNCTION xxx $$ ... $$ SET GUC=, ... is always
related only to GUC. So there should not be any security risk.

It is another reason why GUC and variables should be separated.

I know so there is risk of possibility of collision. There are two
possibilities

a) use different keyword - but it is out of SQL/PSM and out of another
databases.

b) detect possible collision and raise error when assignment is ambiguous.
I am thinking about similar solution used in plpgsql, where is a
possibility of collision between SQL identifier and plpgsql variable.

Regards

Pavel

>
> --
> Robert Haas
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>