On Mon, Jan 24, 2022 at 9:25 AM Dominique Devienne <ddevienne@xxxxxxxxx> wrote:
On Mon, Jan 24, 2022 at 3:48 PM David G. Johnston
<david.g.johnston@xxxxxxxxx> wrote:
> On Monday, January 24, 2022, Dominique Devienne <ddevienne@xxxxxxxxx> wrote:
>>
>> After re-reading
>> https://www.postgresql.org/docs/14/sql-createfunction.html in light of
>> Tom's answer,
>> does that mean that our `SET search_path TO {0}, 'pg_temp'`
>> workaround, in the trigger below,
>> to not depend on the search_path at runtime:
>>
>
> The general trigger documentation is kind enough to point out that the sql language cannot be used to write trigger functions.
OK, failr enough...
But what about:
> I'd really like my DDL statements to NOT contain schema-specific names,
> to ensure proper name resolution independent of the search_path and
> completely "self-contained" in the schema itself.
> Is there any way to achieve that, beside our current `SET search_path` workaround?
Could I please get a definitive answer about this?
There is no way to achieve that.
Objects do not know what schema they are in; and the search_path that is present when the database initiates the SQL transaction itself (e.g., pg_dump, create index) provides only pg_catalog.
In short, search_path is a convenience for interactive users and external applications. Never rely upon it including specific schemas - or any schema at all (besides pg_catalog). Only if you set the search_path yourself can the code that you write depend upon the search_path.
David, in the "clone-schema" thread, you kind of implied I shouldn't
have a set search_path in the triggers,
thus making my DDL schema-specific, but then when I ask about ways to
avoid thus, and have "static" resolution
of names in those trigger functions, I'm not getting alternatives.
I rambled a bit in that email...but I did say "Sometimes limitations cannot be avoided...". I then proceeded to show you an alternative...way of thinking of the problem that would work with this limitation.
Am I the only one to think that a session w/o a seach_path, which
fully qualifies table names,
should behaves exactly the same way than another session that has a
search_path and does not fully qualify table names?
All sessions have a search_path...but if you schema-qualify everything (except what is in pg_catalog) that doesn't really matter. But if the schema-qualified name is "my_custom_schema" then, no, omitting the schema-qualification and relying on search_path means you will get the identical result when my_custom_schema is in the search_path but will get an error when it is not. Both alternatives still include a search_path.
Because that's the only reason I added a set search_path to our
trigger functions. The alternative being to fully-qualify
all object references in those trigger functions, making the DDL even
more "schema-specific". it feels like a catch-22...
Attaching a set search_path and schema-qualifying all object references are equally "schema-specific". It isn't a catch-22, its two options for interacting with a system that is designed to be schema-specific.
That is a lot of theory and generalities but I hope it helps clear things up.
David J.
PS: Does INVOKER vs DEFINER affect name resolution?
Permissions and search_path resolution are independent.
