| From: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Josh Trutwin <josh(at)trutwins(dot)homeip(dot)net>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Empty Updates, ON UPDATE triggers and Rules |
| Date: | 2009-08-06 18:30:52 |
| Message-ID: | 162867790908061130m4a2bfbf1u8445cc4fb0556c49@mail.gmail.com |
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| Lists: | pgsql-general |
2009/8/6 Jeff Davis <pgsql(at)j-davis(dot)com>:
> On Thu, 2009-08-06 at 13:15 -0400, Merlin Moncure wrote:
>> in 8.4 you can (and should) do:
>> WHERE old = new
>
> I couldn't get that to work in a rule.
>
>> IF NEW != OLD THEN -- 8.4 syntax
>
> Does this work correctly in the case of NULLs? It looks like it does,
> but that seems strange, because ROW(1, NULL) = ROW(1, NULL) evaluates to
> NULL. Where is this documented?
>
it's not safe, I thing so correct test is
IF NEW IS NOT DISTINCT FROM OLD THEN ...
regards
Pavel Stehule
> Regards,
> Jeff Davis
>
>
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