Re: CREATE TABLE with a column of type {table name}

Tom Lane wrote:

>elein <elein(at)varlena(dot)com> writes:
>
>
>>This is what I did:
>>CREATE TABLE foo(a int, b int);
>>CREATE TABLE bar(myfoo foo, c int);
>>
>>
>
>This does not actually work, never has worked (at least not as you're
>expecting), and is unlikely to start working in the near future.
>
>The only reason it's not rejected out of hand is that there are still
>traces in the code of an old Postquel feature that had this as its API.
>It did not work anywhere near the way you think, though. As best I
>understood it, what would actually be stored in a row of table bar would
>be the OID of a function declared as "function() returns setof foo", and
>there was some syntax or other for calling this function and getting
>back the potentially-many rows it would return. I believe that in the
>Postquel system there was actually syntactic sugar for creating nameless
>functions of this kind given a Postquel query string that would return
>the correct rowtype; so you could imagine the contents of such a field
>as being a query that would be executed on-demand and return a table.
>Possibly different tables each time you tried it, too.
>
>None of the syntactic sugar is there anymore, and I doubt that the
>underlying ability to call a function whose OID appears in a field
>works anymore either, even though (some of?) the code for it is still
>around. No one's gotten round to ripping it out entirely, but we
>probably should, if it's possible to cause core dumps by creating tables
>with complex types as columns. For sure I have no interest in trying to
>resurrect the Postquel behavior.
>
> regards, tom lane
>
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From an object oriented standpoint the ability to store pointers to
function at the table level would be outstanding. Not that I have the
time or the fortitude to submit a patch for it, just saying think of the
possibilities.