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Re: [HELP] Attribute has an unknown type/is repeated - Mailing list pgsql-general

From Tom Lane
Subject Re: [HELP] Attribute has an unknown type/is repeated
Date
Msg-id 3054.993566241@sss.pgh.pa.us
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In response to [HELP] Attribute has an unknown type/is repeated  ("Itzinger, Oskar" <oitzinger@opec.org>)
List pgsql-general
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"Itzinger, Oskar" <oitzinger@opec.org> writes:
> 1. What exactly is the type of colx in Case 1?
> 2. Why can't PostgreSQL infer that very same type for colx in Case 2?

The || operator is known to yield a result of type "text".  But when the
sum total of the known information is

    '' AS colx

there is no basis at all for assigning a specific type, and it remains
"unknown".

            regards, tom lane

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