Horton

Re: BUG #16644: null value for defaults in OLD variable for trigger

Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

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From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, fedor_erastov@mail.ru
Cc: pgsql-bugs@lists.postgresql.org, Andres Freund <andres@anarazel.de>
Date: 2020-09-30T17:02:39Z
Lists: pgsql-bugs 
On 9/29/20 10:21 PM, Tom Lane wrote:
>
> If you ask me, the proximate cause of this bug was the decision
> to stick attrmissing info into the "constr" field of tupledescs.
> That seems pretty damfool, because there are large parts of the
> system that consider that the constr info is optional and can
> be discarded, or never built to begin with.  Perhaps it's too late
> to revisit that, but we need to take a very very hard look at an
> awful lot of places if we're to stick with that design.
>


:-(


At nearly three years remove my memory is a bit hazy, but IIRC I looked
at all the places (or all I could identify) where it might have mattered
and it looked OK. But I'm not going to bet my life I caught everything,
and maybe I unintentionally provided for a future footgun, which from
your description this appears to be.


I'm not sure what the implications of changing it would be.


cheers


andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. In INSERT/UPDATE, use the table's real tuple descriptor as target.

  2. Fix corner case for a BEFORE ROW UPDATE trigger returning OLD.

  3. Use slots in trigger infrastructure, except for the actual invocation.