Thread: User defined type with text* field

Hi,

 I am trying to create a user defined type with 2 fields
in it, a text* and an Oid. I am not sure what size to
use in the create type command. When I try variable
the back end core dumps. Are there any examples for
doing this sort of thing?  Is it even doable?

Thanks,

Ken

Not yet. :)

The best way to do it currently is to create a table with these fields,
it'll create a type (with the same name as table) automatically.

Why'd you want to do that anyway?

On 30 Jun 2001, Ken K wrote:

> Hi,
>
>  I am trying to create a user defined type with 2 fields
> in it, a text* and an Oid. I am not sure what size to
> use in the create type command. When I try variable
> the back end core dumps. Are there any examples for
> doing this sort of thing?  Is it even doable?
>
> Thanks,
>
> Ken
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
>     (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
>
>

Ken K <kenmail@telocity.com> writes:
>  I am trying to create a user defined type with 2 fields
> in it, a text* and an Oid. I am not sure what size to
> use in the create type command. When I try variable
> the back end core dumps. Are there any examples for
> doing this sort of thing?  Is it even doable?

You can't use any kind of pointer in a datatype --- what is it going to
point to?  There's nothing it could point at that might live as long as
the datavalue on disk will.

You could embed a TEXT value into a larger varlena value, say

        <total length word>
        Oid
        <text value here, beginning with its own length word>

            regards, tom lane

What I want to do is create a Serialize type for storing Java objects.
The text would be the class name and the Oid would point to the record
where the object is stored. I need the class name and not the Oid of the
table because of a problem I have with long class names (> 32
characters).

If I figure out how to make this a "varlena" value would variable then
work
for the length specification in the create type command?

Are there any examples of varlena user types I could look at?

Thanks,

Ken

> Ken K <kenmail@telocity.com> writes:
>>  I am trying to create a user defined type with 2 fields
>> in it, a text* and an Oid. I am not sure what size to
>> use in the create type command. When I try variable
>> the back end core dumps. Are there any examples for
>> doing this sort of thing?  Is it even doable?
>
>You can't use any kind of pointer in a datatype --- what is it going to
>point to?  There's nothing it could point at that might live as long as
>the datavalue on disk will.
>
>You could embed a TEXT value into a larger varlena value, say
>
>                <total length word>
>                Oid
>                <text value here, beginning with its own length word>
>
>
>                        regards, tom lane

On Sun, 1 Jul 2001, Ken Kachnowich wrote:

> What I want to do is create a Serialize type for storing Java objects.
> The text would be the class name and the Oid would point to the record
> where the object is stored. I need the class name and not the Oid of the
> table because of a problem I have with long class names (> 32
> characters).
>
> If I figure out how to make this a "varlena" value would variable then
> work for the length specification in the create type command?
Bytea/varlena types do not have a length, they are unlimited-length (like
text).

>
> Are there any examples of varlena user types I could look at?
>
> Thanks,
>
> Ken
>
> > Ken K <kenmail@telocity.com> writes:
> >>  I am trying to create a user defined type with 2 fields
> >> in it, a text* and an Oid. I am not sure what size to
> >> use in the create type command. When I try variable
> >> the back end core dumps. Are there any examples for
> >> doing this sort of thing?  Is it even doable?
> >
> >You can't use any kind of pointer in a datatype --- what is it going to
> >point to?  There's nothing it could point at that might live as long as
> >the datavalue on disk will.
> >
> >You could embed a TEXT value into a larger varlena value, say
> >
> >                <total length word>
> >                Oid
> >                <text value here, beginning with its own length word>
> >
> >
> >                        regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
> subscribe-nomail command to majordomo@postgresql.org so that your
> message can get through to the mailing list cleanly
>
>