Re: hstores in pl/python

On Dec15, 2010, at 18:33 , Dmitriy Igrishin wrote:
> 2010/12/15 Florian Pflug <fgp@phlo.org>
> On Dec15, 2010, at 16:18 , Dmitriy Igrishin wrote:
> >> 2010/12/15 Florian Pflug <fgp@phlo.org>
> >> On Dec15, 2010, at 02:14 , James William Pye wrote:
> >> > On Dec 13, 2010, at 6:16 PM, Tom Lane wrote:
> >> >> how do you identify which type OID is really hstore?
> >> >
> >> > How about an identification field on pg_type?
> >> >
> >> > CREATE TYPE hstore ..., IDENTIFIER 'org.postgresql.hstore';
> >> > -- Where the "identifier" is an arbitrary string.
> >>
> >> I've wanted something like this a few times when dealing
> >> with custom types within a client. A future protocol version
> >> might even transmit these identifiers instead a the type's OID,
> >> thereby removing the dependency on OID from clients entirely.
> >
> > In some another tread I've proposed CREATE TYPE ... WITH OID...
> Yeah, and I believe type identifiers are probably what you were
> really looking for ;-)
> Indeed, but why OID cannot serve as identifier in this case ? Why to
> encode the code ? :-)

Because there are only 2^32 OIDs, so if people start picking them at
random, sooner or later there will be collisions.

> Type identifiers would solve
> this, by providing an easy and unambiguous way to find specific types.
> Agree with 1st assertion but disagree with 2nd. If I understand correctly,
> "identifier" is a second name for type (object), but Java-styled, right ?
> It probably does solve the problem if there are will be convention that
> types org.postgresql.* are reserved.

Yeah, that'd be the idea. If everyone uses reversed DNS-style names, and
everyone picks a name belonging to a DNS zone under his control, there
cannot be any collisions. At least for java packages, this seems to work
pretty nicely.

> But why not reserve name of type
> "hstore" and prevent the user to create type with this reserved name ?
> All this tells me one thing - to avoid conflicts of naming of specific types
> it is necessary to make them built-in.

None of these solutions scale well.

best regards,
Florian Pflug