Re: Converting contrib SQL functions to new style

> On Apr 14, 2021, at 2:47 PM, Vik Fearing <vik(at)postgresfriends(dot)org> wrote:
>
> On 4/14/21 7:36 PM, Tom Lane wrote:
>> Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> writes:
>>>> On Apr 13, 2021, at 3:26 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>> However I think we may still need an assumption that earthdistance
>>>> and cube are in the same schema --- any comments on that?
>>
>>> This is probably not worth doing, and we are already past feature
>>> freeze, but adding syntax to look up the namespace of an extension might
>>> help.
>>
>> Yeah, that idea was discussed before (perhaps only in private
>> security-team threads, though). We didn't do anything about it because
>> at the time there didn't seem to be pressing need, but in the context
>> of SQL function bodies there's an obvious use-case.
>>
>>> We could get something like this working just inside the CREATE EXTENSION command if we expanded on the @extschema@ idea a bit. At first I thought this idea would suffer race conditions with concurrent modifications of pg_extension or pg_namespace, but it looks like we already have a snapshot when processing the script file, so:
>>
>>> -CREATE DOMAIN earth AS cube
>>> +CREATE DOMAIN @@earthdistance@@::earth AS @@cube@@::cube
>>
>> Right, extending the @extschema@ mechanism is what was discussed,
>> though I think I'd lean towards something like @extschema:cube@
>> to denote the schema of a referenced extension "cube".
>>
>> I'm not sure this is useful enough to break feature freeze for,
>> but I'm +1 for investigating it for v15.
> Just like we have a pseudo "$user" schema, could we have a pseudo
> "$extension" catalog? That should avoid changing grammar rules too much.
>
> CREATE TABLE unaccented_words (
> word "$extension".citext.citext,
> CHECK (word = "$extension".unaccent.unaccent(word)
> );

Having a single variable $extension might help in many cases, but I don't see how to use it to handle the remaining cross-extension references, such as earthdistance needing to reference cube.

—
Mark Dilger
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