--On Donnerstag, Mai 08, 2008 13:28:14 +0100 Simon Riggs
<[EMAIL PROTECTED]> wrote:
On Thu, 2008-05-08 at 13:48 +0200, Bernd Helmle wrote:
--On Mittwoch, Mai 07, 2008 20:38:59 +0100 Simon Riggs
<[EMAIL PROTECTED]> wrote:
>> Where are we on this feature?
>
> Any update, Bernd?
I've merged the patch into current -HEAD and updated some parts. My
current *working* state can be reviewed at
<http://git.postgresql.org/?p=~psoo/postgresql.git;a=shortlog;h=updatabl
e_views>
I'm still not sure how to implement a reliable CHECK OPTION, but short
on time i haven't done a very deep investigation yet. Next idea was to
look at the updatable cursor stuff, maybe something there can be reused.
Your earlier patch seemed to add two rules if the view had a with check
option? One with a pass through and another one with a do-nothing and a
where clause.
As I understand it
CREATE VIEW x AS SELECT * FROM foo WHERE where-clause WITH CHECK OPTION
should generate an INSERT rule like this
CREATE RULE somename AS ON INSERT TO x WHERE where-clause DO INSERT ...
This was indeed the implementation i've proposed. We have rejected this
idea then because it doesn't work with volatile functions reliable due to
double evaluation:
<http://archives.postgresql.org/pgsql-patches/2006-08/msg00483.php>
Tom's example even demonstrates a serious constraint in rule based updates,
since you get side effects in such conditions you won't expect, even
without a CHECK OPTION.
which seems straightforward, no?
The SQLStandard default is CASCADED and it seems easier not to worry too
much about the LOCAL option until we have the basics working. I'm not
even sure that we *want* the LOCAL option anyway having read what it
means, plus it isn't supported by many other DBMS.
Do you store anything in the catalog to mark the view as updatable or
not? I couldn't see that but it seemed easier than trying to resolve all
of the updatability characteristics at run-time.
I'm not sure want you mean, but pg_rewrite.ev_kind stores the nature of the
rule. Updatability is determined by the checkTree() function internally.
It's easy to query pg_rewrite to examine wether a view is updatable or not.
I may be able to help some with the patch, if you'd like?
You're welcome ;)
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com
--
Thanks
Bernd
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