Re: hstores in pl/python

2010/12/15 Dmitriy Igrishin <dmitigr@gmail.com>:
>
>
> 2010/12/15 Florian Pflug <fgp@phlo.org>
>>
>> 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.
>
> Yes, but range of PostgreSQL's OIDs can be reserved. One or even ten
> millions, e.g. can be enough.
>
>>
>> > 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.
>
> Well, If there are will be identifiers for each type, e.g.
> org.postgresql.integer, why
> they need to be built-in ? For "historical reasons" ? :-)
> Let them also be in contribs...

some types are used in system tables, so without support of these
types, then you can't to add a new types. It's a egg-chicken problem

Pavel

>>
>> best regards,
>> Florian Pflug
>>
>>
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> --
> // Dmitriy.
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