Re: Triggers and System Tables

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От Jan Wieck
Тема Re: Triggers and System Tables
Дата
Msg-id 200204161559.g3GFxUB11548@saturn.janwieck.net
обсуждение исходный текст
Ответ на Triggers and System Tables  (Hans-Juergen Schoenig <hs@cybertec.at>)
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Hans-Juergen Schoenig wrote:
> I have a brief question concerning triggers and system tables:
> Why is it not allowed to trigger a system table? I guess it could be
> useful from time to time.

    Because  system  tables  are  often  modified  by direct heap
    access, rather than regular query plans handled  through  the
    executor. The direct heap access doesn't invoke the triggers.

    Even if we get this problem "fixed" (I don't really  consider
    it  broken),  what if you setup a ON UPDATE OR DELETE trigger
    for pg_proc, that is broken? You cannot remove or fix it  any
    more,  so  your  pg_proc  system  catalog is frozen, forever,
    irreversable, infinitely! That's bad!


Jan

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