The reasons are simple, particularly, I don't want to bloat SQL
with CAST or ::. Its not elegant and looks ugly. If I need to bind
e.g. int or short I don't want write ::integer or ::smallint in SQL,
because I can easily map int to integer via OID...
I don't clearly understand how set_next_pg_type_oid code
can helps me.
Also I don't understand why cache of OIDs can't be used to get
results via PQexecParams in a binary form ? I can do it.
Querying the db for OIDs seems to me a good idea. But:
1. Since the structure of pg_type system catalog can be changed
the developer must be able to determine a libpq version to be able
to implement cross libpq-version of the product (especially library).
So PQversion() should be there :-)
2. To avoid memory overheads (especially in WEB environments)
it would be nice if libpq will keep cache of types metadata as a static
structure per database and provide an API to work with (in this case I
totally agree with Pavel). At least, the API should support rereading
the cache. In this case 1. (PQversion) is not needed -- libpq care it
itself :-)
2010/12/7 Pavel Stehule
<pavel.stehule@gmail.com>2010/12/7 Tom Lane <tgl@sss.pgh.pa.us>:
> Merlin Moncure <
mmoncure@gmail.com> writes:
>> On Tue, Dec 7, 2010 at 11:49 AM, Tom Lane <
tgl@sss.pgh.pa.us> wrote:
>>> Say what? He didn't say that, he said "don't assume that user-defined
>>> types have hard-wired OIDs".
>
>> Well, you're right, strictly speaking. Of course, the OP is not
>> assuming it, he is enforcing it.
>
> No, he's wishing he could enforce it. Which will work, mostly, until
> the day it doesn't because of a pre-existing collision. And then he'll
> be up the creek with a lot of software that he can't fix readily. I
> concur with Andrew's advice: don't go there in the first place. Use a
> cache to mitigate the costs of looking up user-defined OIDs, and you
> won't regret it later.
>
supports some cache and some API for "custom oid"? Now, a work with
custom types on C level is little bit unfriendly. There isn't a
problem with builtin types - these are well defined. I agree, so
direct access to oids for custom types isn't a good idea. But some
general API or pattern can be nice - mainly for client side.
regards
Pavel
> regards, tom lane
>
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--
// Dmitriy.