Re: [HACKERS] current CVS snapshot of pgsql crash ...

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От Bruce Momjian
Тема Re: [HACKERS] current CVS snapshot of pgsql crash ...
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Msg-id 199907072355.TAA16202@candle.pha.pa.us
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Ответ на Re: [HACKERS] current CVS snapshot of pgsql crash ...  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [HACKERS] current CVS snapshot of pgsql crash ...  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
Re-added to TODO list  :-)
* Fix typein/out functions to not be user-callable


> wieck@debis.com (Jan Wieck) writes:
> >>>> For that matter, why do we allow user expressions to call the type
> >>>> input/output functions at all?  They're not really usable as SQL
> >>>> functions AFAICS...
> 
> >     Doing  textout(byteaout(...  really makes no sense. But being
> >     able to do a textin(mytypeout(... does  make  sense  for  me.
> >     Without   that,  there  MUST  be  type  casting  support  for
> >     MYTYPE->TEXT in the parser.
> 
> The real problem here is that the type system needs to have a notion
> of "C string" as a datatype so that the type input and output functions
> can be declared *properly* with the true nature of their inputs and
> results given correctly.  Then typeain(typebout(typebvalue)) would work
> and textout(byteaout(...)) would be rejected, as it should be.
> 
> The typechecking escape convention (zero in the proargtypes signature)
> should only be used for functions that really do accept any kind of
> datum.  I think there are some (count(*) for one) but not many.
> 
> The "C string" type is not quite a real type, because we don't want to
> let people declare columns of that type (I assume).  OTOH it must be
> real enough to let people declare user-defined functions that accept or
> return it.  Right now, the I/O functions for user-defined types are
> supposed to be declared to take or return type OPAQUE, but I think
> that pseudo-type is being used for too many different things.
> 
> Obviously none of this is going to happen for 6.5, but it should go
> on the TODO list.
> 
>             regards, tom lane
> 


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