Re: dealing with extension dependencies that aren't quite 'e'

On Mon, Mar 21, 2016 at 2:19 PM, Abhijit Menon-Sen <ams(at)2ndquadrant(dot)com>
wrote:

> At 2016-03-21 13:04:33 +0300, a(dot)korotkov(at)postgrespro(dot)ru wrote:
> >
> > I'm not sure why we want to make new dependency type by ALTER FUNCTION
> > command, not ALTER EXTENSION?
>
> It's a matter of semantics. It means something very different than what
> an 'e' dependency means. The extension doesn't own the function (and so
> pg_dump shouldn't ignore it), but the function depends on the extension
> (and so dropping the extension should drop it).
>
> > The argument could be that 'x' dependency type would be used for other
> > objects not extensions.
>
> I suppose this is possible, but yes, I agree with you that it's not
> clear how or why this would be useful.
>
> > So, I would prefer this patch to extend ALTER EXTENSION command while
> > it's aimed to this particular problem.
>
> OK, so that's what the patch does, and it's certainly the simplest
> approach for reasons discussed earlier (though perhaps not as clear
> semantically as the ALTER FUNCTION approach). But:
>
> > I even think we could extend existent grammar rule
> >
> > | ALTER EXTENSION name add_drop FUNCTION
> function_with_argtypes
> > > *************** AlterExtensionContentsStmt:
> > > *** 3982,3987 ****
> > > --- 3987,3993 ----
> > > n->objtype = OBJECT_FUNCTION;
> > > n->objname = $6->funcname;
> > > n->objargs = $6->funcargs;
> > > + n->deptype = 'e';
> > > $$ = (Node *)n;
> > > }
>
> How exactly do you propose to do this, i.e., what would the final
> command to declare an 'x' dependency look like?
>

I'm proposed something like this.

extension_dependency_type:
DEPENDENT { $$ = 'x'; }
| /*EMPTY*/ { $$ = 'e'; }
;

...
| ALTER EXTENSION name add_drop extension_dependency_type FUNCTION
function_with_argtypes
{
AlterExtensionContentsStmt *n = makeNode(AlterExtensionContentsStmt);
n->extname = $3;
n->action = $4;
n->objtype = OBJECT_FUNCTION;
n->objname = $7->funcname;
n->objargs = $7->funcargs;
n->deptype = $5;
$$ = (Node *)n;
}

I didn't try it. Probably it causes a grammar conflicts. In this case I
don't insist on it.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company