From: | Scara Maccai <m_lists(at)yahoo(dot)it> |
---|---|
To: | Paolo Saudin <paolo(at)ecometer(dot)it> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: R: R: complex custom aggregate function |
Date: | 2009-02-02 14:30:38 |
Message-ID: | 898922.56352.qm@web24612.mail.ird.yahoo.com |
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Lists: | pgsql-general |
Paolo Saudin wrote:
> I use a master table with a "fulldate" field and filled with sequential dates to
> fill gaps when meteo data is missing.
I'm sorry, I still don't get it: how can you be sure that postgresql won't call perl_sliding_mean with not-ordered timestamps-data? I don't mean only in case of holes.
The "order by" as far as I know is usually done at the very end of the plan, so I don't think it can affect the order of the data passed to the function...
Suppose you have data like:
01/01/2009 1.00 -7
01/01/2009 2.00 -7,1
01/01/2009 3.00 -5,3
01/01/2009 4.00 -5,2
01/01/2009 5.00 -4,8
01/01/2009 6.00 -4
What does prevent postgresql to call your function with data in this order:
01/01/2009 6.00 -4
01/01/2009 1.00 -7
01/01/2009 5.00 -4,8
01/01/2009 3.00 -5,3
01/01/2009 2.00 -7,1
01/01/2009 4.00 -5,2
and reorder ("order by fulltime") at the very end (when results from the function are already out)?
Thank you for your patience.
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