From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Nicolas Aragon <nyco(at)jet(dot)es> |
Cc: | pgsql-interfaces(at)postgreSQL(dot)org |
Subject: | Re: [INTERFACES] types oids |
Date: | 1999-08-17 00:23:31 |
Message-ID: | 6511.934849411@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-interfaces |
Nicolas Aragon <nyco(at)jet(dot)es> writes:
> But this leads me to new questions because it seems that standard types
> aren't hardcoded anywhere. pg_type tells me the name, size and some other
> information about the type. But what about the "kind" of the type (numeric,
> text, date...)?
You pretty much have to know from the name what the datatype is.
Postgres doesn't have any type categorization like that. (Maybe it
should ... I think there are some hacks in the parser that amount to
categorizing the standard datatypes, but that knowledge is not visible
outside the parser.)
> I can only think of comparing the name with a list of names for standard
> types. Is there another simpler method? A standard relation between standard
> types and their OIDs?
In reality, the OIDs assigned to standard types like "bool" and "int4"
are unlikely ever to change; they certainly will not change faster than
once per Postgres major release. You could probably get away with
hard-wiring the knowledge that OID 16 == bool, say. If that seems a
little too ugly, reading the OIDs for known types during startup is
plenty good enough.
If you are dealing with user-defined types, looking up the OIDs at
startup is the way to go. (User type OIDs could change across a
database dump/reload, so hardwiring those would be a bad idea.)
> I can even think that.... is the user (admin) allowed to change the names
> of standard types?
Not if he wants things to keep working ;-)
> Another, more trivial question: do you know where to find nice logos
> for postgres?
See the website.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Mengelbier, Magnus | 1999-08-17 07:47:50 | Error using Perl interface |
Previous Message | Mark Dzmura | 1999-08-16 23:58:44 | A few more JDBC meta-data questions... |