RE: [HACKERS] copyObject() ?

Hello all,

> -----Original Message-----
> From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
> Sent: Wednesday, February 24, 1999 12:16 AM
> To: Hiroshi Inoue
> Cc: pgsql-hackers
> Subject: Re: [HACKERS] copyObject() ? 
> 
> 
> "Hiroshi Inoue" <Inoue@tpf.co.jp> writes:
> > AFAIC the relation between objects is not copied correctly 
> > by copyObject() (i.e the same pointers to an object are copied 
> > to different pointers by copyObject()). 
> 
> True, but it seems irrelevant to me --- as Jan Wieck was just pointing
> out, no code should ever depend on pointer-equality in parse trees or
> plan trees anyway.
>

If multiple references are not necessary,why we don't allocate diffrent 
objects which have equal contents from the start ?

It seems very difficult to prevent developpers from using the following 
fact implicitly.
The same pointers always point the equal contents.           ^^^^^^^^

Different pointers (as copyObject() currently generates) which have 
equal contents may have different contents some time.
Isn't it a significant differnce ?

> > There is a way to maintain the list of (old,new) pairs during 
> > copyObject() operations.
> 
> I think we'd be better off fixing any places that mistakenly assume
> pointer compare is sufficient.  You didn't say which version you were
> testing, 

My environment is v6.4.2.
OK,I would test my cases again after the release of 6.5-BETA(v6.4.3?).
TIA

Hiroshi Inoue
Inoue@tpf.co.jp