Re: Function call order dependency

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От pgsql@mohawksoft.com
Тема Re: Function call order dependency
Дата
Msg-id 45309.64.119.130.186.1220458259.squirrel@mail.mohawksoft.com
обсуждение исходный текст
Ответ на Re: Function call order dependency  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Function call order dependency
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> pgsql@mohawksoft.com writes:
>> For example I'll use the Oracle "contains" function, though this is not
>> exactly what I'm doing, it just illustrates the issue clearly.
>
>> select *, score(1) from mytable where contains(mytable.title, 'Winding
>> Road', 1) order by score(1);
>
>> The "contains" function does a match against mytable.title for the term
>> 'Winding Road' and both returns and saves an integer score which may be
>> retrieved later using the "score(...)" function.
>
> This is just a bad, bad idea.  Side-effects in a WHERE-clause function
> are guaranteed to cause headaches.  When (not if) it breaks, you get
> to keep both pieces.

I was kind of afraid of that. So, how could one implement such a function
set?


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