Re: Inheritance in PostgreSQL
| От | Merlin Moncure |
|---|---|
| Тема | Re: Inheritance in PostgreSQL |
| Дата | |
| Msg-id | CAHyXU0wyo7dr-cq=S96JBo3my7R_MKgSHhWKb7uNCC2a_z691w@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Inheritance in PostgreSQL (Thomas Kellerer <shammat@gmx.net>) |
| Список | pgsql-general |
On Wed, Oct 18, 2023 at 7:43 AM Thomas Kellerer <shammat@gmx.net> wrote:
Merlin Moncure schrieb am 18.10.2023 um 03:20:
> The only thing you can't really do in SQL easily without writing
> nasty triggers are things like, 'this table must be linked from one
> and only one of these candidate tables'. I think the language
> probably ought to support this, but I don't think postgres would
> unless the standard did.
Isn't that what assertions are intended to solve in the SQL standard?
Hm, interesting, <googles> ...maybe, maybe not. SQL '92 -- wow. guessing why not: Are they deferrable, always deferred? Doesn't seem like it, simple inheritance cases would seem problematic otherwise, chicken/egg conditions. This might explain why they are not in common use despite being innovated 30 years ago. Here is an Oracle discussion on the topic:
...with the discussion implying that interaction with the transaction state may be an unsolved problem, at least within oracle. I suspect there may also be challenges relating to performant implementation. Sadly, I think the correct approach remains to utilize complex triggers, or nothing.
merlin
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