Re: Analysis Function - Mailing list pgsql-performance

From Magnus Hagander
Subject Re: Analysis Function
Date
Msg-id AANLkTinu31G_D12lk6TH3ecinHqLWOEv7dMtq_tnnwCn@mail.gmail.com
Whole thread Raw
In response to Re: Analysis Function  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
On Sun, Jun 13, 2010 at 17:58, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Magnus Hagander <magnus@hagander.net> writes:
>> On Sun, Jun 13, 2010 at 17:42, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> ... (We presumably want
>>> timezone to default to the system timezone setting, but I wonder how
>>> we should make that work --- should an empty string be treated as
>>> meaning that?)
>
>> Umm. NULL could be made to mean that, or we could provicde two
>> different versions - one that takes TZ and one that doesn't.
>
> Using NULL like that seems a bit awkward: for one thing it'd mean the
> function couldn't be STRICT, and also it'd be bizarre that only this
> one argument could be null without leading to a null result.

Hmm, yeah.


> And two separate functions isn't good either.  Basically, I think it's
> important that there be a way to specify an explicit parameter value
> that behaves identically to the default.

In that case, empty string seems fairly reasonable - if you look at
the text based parsing, that's what we do if the timezone is an "empty
string" (meaning not specified).



>> And a third, construct_time(), no?
>
> Yeah, maybe ... do you think there's any demand for it?

Yes, I think there is. Plus, it's for completeness :-)

--
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

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