Re: pg_execute_from_file review

Tom Lane <tgl@sss.pgh.pa.us> writes:
> There's a difference between whether an extension as such is considered
> to belong to a schema and whether its contained objects do.  We can't
> really avoid the fact that functions, operators, etc must be assigned to
> some particular schema.  It seems not particularly important that
> extension names be schema-qualified, though --- the use-case for having
> two different extensions named "foo" installed simultaneously seems
> pretty darn small.  On the other hand, if we were enforcing that all
> objects contained in an extension belong to the same schema, it'd make
> logistical sense to consider that the extension itself belongs to that
> schema as well.  But last I heard we didn't want to enforce such a
> restriction.

Very good summary, thank you, that's exactly the ideas I've been working
with. Which ain't surprising, after all we've been talking about this
for 18 months already :)

So in the current patch, extensions are not schema qualified.

> I believe what the search_path substitution is actually about is to
> provide a convenient shorthand for the case that all the contained
> objects do indeed live in one schema, and you'd like to be able to
> select that schema at CREATE EXTENSION time.  Which seems like a useful
> feature for a common case.  We've certainly heard multiple complaints
> about the fact that you can't do that easily now.

Exactly.  It's just a useful little thing, but given that it depends on
how the script is written, maybe the right interface would be a 2-steps
process, so that either it does what you want or you get an error.

Current patch:
 CREATE EXTENSION foo WITH SCHEMA bar;
 If foo's script isn't using @extschema@ or if it is using more than one schema, executing the script will not do
anythinglike what you want to --- currently that's extension's author problem.
 

Other idea:
  CREATE EXTENSION foo;  ALTER EXTENSION foo SET SCHEMA utils;
  CREATE EXTENSION bar;  ALTER EXTENSION bar SET SCHEMA utils;  ERROR: the extension "bar" has installed objects in
morethan one schema  DETAIL: extension depends on schema "public" and "baz"   HINT: use pg_extension_objects() to list
bar'sobjects
 

> BTW, I did think of a case where substitution solves a problem we don't
> presently have any other solution for: referring to the target schema
> within the definition of a contained object.  As an example, you might
> wish to attach "SET search_path = @target_schema@" to the definition of
> a SQL function in an extension, to prevent search-path-related security
> issues in the use of the function.  Without substitution you'll be
> reduced to hard-wiring the name of the target schema.

Right.

Regards,
-- 
Dimitri Fontaine
http://2ndQuadrant.fr