Re: [HACKERS] pg_dump data structures for triggers

[Tom Lane]

Vik Fearing  writes:
> On 02/04/2016 01:44 AM, Tom Lane wrote:
>> I'm looking into fixing the problem reported here:
>> http://www.postgresql.org/message-id/1445a624-d09f-4b51-9c41-46ba1e2d6...@neveragain.de
>> namely that if we split a view into a table + rule (because of circular
>> dependencies), parallel pg_restore fails to ensure that it creates any
>> triggers for the view only after creating the rule.  If it tries to
>> create the triggers first, the backend may barf because they're the wrong
>> type of triggers for a plain table.

> No objections to this, but my "better idea" is simply to allow INSTEAD
> OF triggers on tables like discussed last year.
> http://www.postgresql.org/message-id/14c6fe168a9-1012-10...@webprd-a87.mail.aol.com

That sounds like a new feature, and not something we'd want to backpatch.

regards, tom lane


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Re: [HACKERS] pg_dump data structures for triggers

[Vik Fearing]

On 02/04/2016 01:44 AM, Tom Lane wrote:
> I'm looking into fixing the problem reported here:
> http://www.postgresql.org/message-id/1445a624-d09f-4b51-9c41-46ba1e2d6...@neveragain.de
> namely that if we split a view into a table + rule (because of circular
> dependencies), parallel pg_restore fails to ensure that it creates any
> triggers for the view only after creating the rule.  If it tries to
> create the triggers first, the backend may barf because they're the wrong
> type of triggers for a plain table.
> 
> While it's not that hard to make pg_dump add some more dependencies while
> breaking a circular dependency, there's a small problem of finding the
> view's triggers so we can attach those dependencies to them.  AFAICS, with
> the current pg_dump data structures, there is actually no better way to
> do that than to iterate through every DumpableObject known to pg_dump to
> see which of them are TriggerInfos pointing to the view relation :-(.
> 
> What I have in mind is to add linked-list fields to TableInfo and
> TriggerInfo to allow all the triggers of a table to be found by chasing
> a list.  The increment in the size of those data structures isn't much,
> and we may have other uses for such an ability later.
> 
> Anybody have an objection or better idea?

No objections to this, but my "better idea" is simply to allow INSTEAD
OF triggers on tables like discussed last year.
http://www.postgresql.org/message-id/14c6fe168a9-1012-10...@webprd-a87.mail.aol.com
-- 
Vik Fearing  +33 6 46 75 15 36
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support


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