Re: Problem with FK referential actions - Mailing list pgsql-hackers

From Jan Wieck
Subject Re: Problem with FK referential actions
Date
Msg-id 200108011748.f71HmMU02205@jupiter.us.greatbridge.com
Whole thread Raw
In response to Problem with FK referential actions  (Stephan Szabo <sszabo@megazone23.bigpanda.com>)
Responses Re: Problem with FK referential actions
List pgsql-hackers
Stephan Szabo wrote:
> The output from the select, should I believe be (3,1), (4,1)
> not (4,1), (4,1).  I think we're violating General Rule 4 (I think
> that's it) on the referential constraint definition ("For every
> row of the referenced table, its matching rows, unique matching
> rows, and non-unique matching rows are determined immediately
> before the execution of any SQL-statement.  No new matching
> rows are added during the execution of that SQL-statement.")
> because when the update cascade gets done for the 2 row, we've
> changed the (2,1) to (3,1) which then gets hit by the update
> cascade on the 3 row.
>
> I was wondering if you had any thoughts on an easy way around
> it within what we have. :)
   I  think  you're  right  in  that  it  is a bug and where the   problem is.  Now to get around it isn't easy.
Especially in   the  deferred  constraint  area,  it  is  important  that the   triggers see the changes made during
all commands.  But  for   the  cascade to hit the right rows only, the scans (done with   key qualification) would have
tobe done with a scan  command   counter equal to the original queries command counter.
 
   The  old (more buggy?) behaviour should've been this annoying   "triggered data change violation".  But  some  folks
thought   it'd  be  a good idea to rip out that bug. See, these are the   days when you miss the old bugs :-)
 


Jan

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