Re: proposal: early casting in plpgsql

2009/5/28 Tom Lane <tgl@sss.pgh.pa.us>:
> Pavel Stehule <pavel.stehule@gmail.com> writes:
>> I propose for types with typmod -1 early casting - etc casting to
>> target type on planner level. We cannot use this method for defined
>> typmod, because we would to raise exception for following situation:
>
> What existing coding habits will this break?

I don't know about any. Actually we don't have "variant datatype", so
this should not impact on existing applications.

 People have long been
> accustomed to use plpgsql for end-runs around SQL casting behavior,
> so I'm not really convinced by the idea that "make it more like SQL"
> is automatically a good thing.
>

for typmod others then -1 we should to use IO cast - but we should to
check, if it's one from known casts.

without "strict mode" this should be fully compatible (if we could to
expect so our casting functions are correct).

> Also, it seems bizarre and inconsistent that it would work one way
> for variables with a typmod and an entirely different way for those
> without.  How will you explain that to users who never heard of a
> typmod?
>

Now I thing so this should be solved well too. We need two kind of
casting functions - what we have - CASTs with INOUT and CASTs with
functions. For variables with typmod we have to call CASTs with INOUT.

>                        regards, tom lane
>