Re: Should PG backend know how to represent metadata?

At 10:46 17/07/00 -0400, Tom Lane wrote:
>Philip Warner <pjw@rhyme.com.au> writes:
>> I don't think we have functions that return multiple rows,
>
>We do, although they're a bit unwieldy to use; might be better to avoid
>that feature.  I'd be inclined to avoid the issue, and just have the
>function return one result (which might contain newlines for readability
>of course).

Not sure that this has the flexibility needed for tables; I'd like the
calling application to be able to get just the base table definition with
no constraints, and also request the related items (constraints, indexes
etc). I also want to avoid the caller from having to parse the output in
any way.

Perhaps it is best left as an API-only feature, but now I have thought of
an SQL interface, I do like the idea.


>
>> Which brings me to my next idea:
>
>>     select defn from pg_dump where type='table and name = 'foo'
>> or
>>     select related_items from pg_dump where type='table and name = 'foo'
>
>> where pg_dump can be implemented via a rewrite rule....maybe.
>
>The rewrite rule couldn't do any of the heavy lifting; it'd still end
>up calling a function.  A view like pg_rules might not be a bad idea,
>but you should plan on exposing the underlying function for
>flexibility.

Sounds fine. Only I'm not sure that a rule can do it - AFAICT I still need
some underlying table to select from when I use a rule...unless I can fake
a result set for a 'special' table?


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