Horton

Re: Constraint documentation

Patrick Francelle <patrick@francelle.name>

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From: Patrick Francelle <patrick@francelle.name>
To: Pantelis Theodosiou <ypercube@gmail.com>, Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Lætitia Avrot <laetitia.avrot@gmail.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, bpd0018@gmail.com, vik.fearing@2ndquadrant.com, coelho@cri.ensmp.fr, pgsql-hackers@lists.postgresql.org
Date: 2018-10-30T15:50:13Z
Lists: pgsql-hackers

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On 08/10/18 07:02, Pantelis Theodosiou wrote:
> 
> I like this:
> 
>> "Postgres does not currently support CHECK constraints containing
> queries, therefore we recommend to avoid them."
> 
> Perhaps adding:
> 
>> CHECK constraints are currently meant to be used as *row constraints*
> only.
>> Use - if possible - UNIQUE or EXCLUDE constraints. for constraints
> that involve many or all rows of a table,
>> and FOREIGN KEY constraints for cross table constraints.
>> More complex constraints will be available when ASSERTION are implemented.
> 
> And then adding some warning about using functions in CHECK constraints
> to bypass current limitations.
> 
> Pantelis Theodsoiou

Hi,

I have rewritten the patch to include your remarks.
In fact, the whole patch is now based on it, so thank you.


Patrick Francelle

Commits

  1. Clarify that cross-row constraints are unsupported