Re: Patch for 8.5, transformationHook - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Patch for 8.5, transformationHook
Date
Msg-id 12390.1249923462@sss.pgh.pa.us
Whole thread Raw
In response to Re: Patch for 8.5, transformationHook  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
List pgsql-hackers
"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> Peter Eisentraut <peter_e@gmx.net> wrote: 
>> reimplement a bunch of core functionality like COALESCE
> If such an effort could reduce the astonishment factor for the
> following, it would justify a certain amount of effort, in my view:
> test=# select pg_typeof('x');
>  pg_typeof
> -----------
>  unknown
> (1 row)

> test=# select pg_typeof(null);
>  pg_typeof
> -----------
>  unknown
> (1 row)

> test=# select pg_typeof(coalesce(null, null));
>  pg_typeof
> -----------
>  text
> (1 row)

The astonishment factor there has nothing to do with how the behavior is
inserted into the parser; it's a property of our type resolution rules.
        regards, tom lane


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