Re: Fixing row comparison semantics

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От Tom Lane
Тема Re: Fixing row comparison semantics
Дата
Msg-id 9884.1135613268@sss.pgh.pa.us
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Ответ на Re: Fixing row comparison semantics  ("Pavel Stehule" <pavel.stehule@hotmail.com>)
Ответы Re: Fixing row comparison semantics  ("Pavel Stehule" <pavel.stehule@hotmail.com>)
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"Pavel Stehule" <pavel.stehule@hotmail.com> writes:
>> Right now, '(a, b) < (1, 2)' is processed as 'a < 1 and b < 2', but
>> the SQL standard requires it to be processed as a column-by-column
>> comparison, so the proper comparison is '(a < 1) OR (a = 1 AND b < 2)'

> Can we save current behave (with small modification) with other operator, 
> like <*

Huh?  The only "current behavior" with other operators is failure:

regression=# select (1,1) <* (1,2);
ERROR:  operator <* is not supported for row expressions

In any case, you can get the equivalent of the current behavior by
writing out1 <* 1 AND 1 <* 2
so I don't see any strong need to support non-SQL-spec behaviors here.
        regards, tom lane


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