Re: [PATCHES] libpq type system 0.9a

On Tue, 2008-04-08 at 22:15 -0400, Tom Lane wrote:
> The biggie is floating-point format.  IEEE standard is not quite
> universal ... and even for platforms that fully adhere to that standard,
> it's not entirely clear that we get the endianness issues correct.
> There used to be platforms where FP and integer endianness were
> different; is anyone sure that's no longer the case?
> 

These seem solvable with platform-specific code in the send/recv for the
applicable types. I don't have such machines to test on, however.

> But I'll agree that cross-version hazards are a much more clear and
> present danger.  We've already broken binary compatibility at least once
> since the current binary-I/O system was instituted (intervals now have
> three fields not two) and there are obvious candidates for future
> breakage, such as text locale/encoding support.

Is there a lower standard for maintaining compatibility for external
binary representations than external text representations? 

It seems that there would have to be more flexibility in changing the
external binary representation if a type between versions in order to
"be cheap to convert to internal form" as the docs say here:
http://www.postgresql.org/docs/8.3/static/sql-createtype.html

Regards,Jeff Davis