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Data Bases > Pgsql Hackers > Re: Resolving p...
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Re: Resolving polymorphic functions with related

by simon@[EMAIL PROTECTED] (Simon Riggs) Jul 3, 2008 at 01:34 PM

On Thu, 2008-07-03 at 14:11 +0300, Heikki Lin****angas wrote:

> > What I'd like it to do is to recognise that the 0 should be cast
> > implicitly to another datatype within the same family. I want and
expect
> >  nvl(char_column, 0)
> > to fail, but I expect the various numeric/integer types we have to
play
> > nicely together without tears.
> 
> So, it would be analogous to the 'unknown' type, but for numeric 
> literals instead of text literals. Seems reasonable. It still wouldn't 
> allow nvl(1::bigint, 2::int4), though, just as the unknown type doesn't 
> help with nvl('foo'::text, 'bar'::varchar).

Well, it would be nice if we could work with the unknown type also, but
I don't expect that's meaningful.

Yet
	func(column_of_typeX, constant)
ought to be able to resolve correctly when
* no function exists with signature
	func(typeX, typeY)
* yet there exists a function
	func(anyelement, anyelement)
* and an implicit cast exists typeY => typeX
(assuming constant is normally resolved to typeY)

> > If we can do it for indexes, can we do it for polymorphic functions
also
> > when there is no matching function?
> 
> Umm, what do indexes have to do with this?

Nothing, except that we solved implicit casting for that situation, so
perhaps it is possible for this situation...

Anyway, just posting for reference. Workarounds exist, just wanted to
make sure the issue was mentioned.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Sup****t


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 9 Posts in Topic:
Resolving polymorphic functions with related datatypes
simon@[EMAIL PROTECTED]   2008-07-03 10:36:09 
Re: Resolving polymorphic functions with related datatypes
pavel.stehule@[EMAIL PROT  2008-07-03 12:22:21 
Re: Resolving polymorphic functions with related
simon@[EMAIL PROTECTED]   2008-07-03 11:51:38 
Re: Resolving polymorphic functions with related datatypes
heikki@[EMAIL PROTECTED]   2008-07-03 14:11:34 
Re: Resolving polymorphic functions with related
simon@[EMAIL PROTECTED]   2008-07-03 13:34:05 
Re: Resolving polymorphic functions with relateddatatypes
stark@[EMAIL PROTECTED]   2008-07-03 13:54:29 
Re: Resolving polymorphic functions with relateddatatypes
tgl@[EMAIL PROTECTED] (T  2008-07-03 12:01:25 
Re: Resolving polymorphic functions with relateddatatypes
simon@[EMAIL PROTECTED]   2008-07-03 14:24:06 
Re: Resolving polymorphic functions with relateddatatypes
pavel.stehule@[EMAIL PROT  2008-07-03 19:42:56 

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tan12V112 Fri Dec 5 8:02:27 CST 2008.