Re: BUG #15960: ON CONFLICT Trying accessing to variables - Mailing list pgsql-bugs

From Andres Freund
Subject Re: BUG #15960: ON CONFLICT Trying accessing to variables
Date
Msg-id 20190815194213.hskbzb3vcpij5tiy@alap3.anarazel.de
Whole thread Raw
In response to Re: BUG #15960: ON CONFLICT Trying accessing to variables  (Peter Geoghegan <pg@bowt.ie>)
Responses Re: BUG #15960: ON CONFLICT Trying accessing to variables  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-bugs
Hi,

On 2019-08-15 10:09:14 -0700, Peter Geoghegan wrote:
> On Thu, Aug 15, 2019 at 10:05 AM Andres Freund <andres@anarazel.de> wrote:
> > I'm not sure I quite buy that.  There is no actual ambiguity here.  I don't buy the variable referencing a constant
-that'd not correctly work for subsequent uses of the statement if the variable differs - don't think we'd have
replacingetc set up. Nor do I think we would even evaluate The variable/param.
 
> 
> If we were going to fix this, then it would probably be because of the
> issue around it working inconsistently when the variable differs over
> multiple calls. That's something that we've heard about at least once
> before. I'm not excited about fixing the ambiguity issue.

Well, I think it'd currently error out in many cases (presumably once
we're over the 5 executions limit or such?), so that'd prevent the error
from actually causing problems like that.


> > Seems like it's more a question of preventing the hook from resolving things at that point?
> 
> I don't know.

Seems like we'd just need a new EXPR_KIND_*, maybe
EXPR_KIND_ARBITER_EXPRESSION, which plpgsql's column hook would just
ignore.

Greetings,

Andres Freund



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