derby & hibernate & type 'text'

[Andy Rozman <an...@triera.net>]

Hi !

I am new to derby and I have one question. I am using Hibernate with my 
application and I am having little problems with Derby... (I used same 
db configutaion on PostgreSQL, Mckoi and HsqlDb)...

It seems that type text (which should be unlimited varchar) is 
interpreted as CLOB(255). I don't know where this happens but my 
application now fails... Is this Derby problem or Hibernate? I am using 
latest of Derby (10.3.2.1) and Hibernate 3.1.

Which is longest varchar format in Derby?

If someone uses Hibernate with Derby I would be thankful for any help...

Andy

Re: derby & hibernate & type 'text'

[Thomas Nielsen <Th...@Sun.COM>]

Andy Rozman wrote:
> It seems that type text (which should be unlimited varchar) is 
> interpreted as CLOB(255). I don't know where this happens but my 
> application now fails... Is this Derby problem or Hibernate? I am using 
> latest of Derby (10.3.2.1) and Hibernate 3.1.

Hi Andy,

Hibernate seems to map its 'text' type to a database clob, not a 
database varchar. This is Hibernates doing, not Derbys. See attached 
link to Hibernate "cheat sheet"[1].

You might be better off with using Hibernates 'string' type which maps 
to a database varchar type?

I'm not sure exactly why it fails using 'text' and a clob with derby, 
but I do know there are a few clob related fixes in the upcoming 10.4 
release.

The release candidate of Derby 10.4 is now available[2], and the 
official release should be just around the corner. Maybe you could give 
the RC a quick spin to see if the problem is solved?

Cheers,
Thomas

[1] http://ndpsoftware.com/HibernateMappingCheatSheet.html
[2] http://wiki.apache.org/db-derby/DerbyTenFourRelease  --> 
ReleaseCandidates
-- 
Thomas Nielsen

Re: derby & hibernate & type 'text'

[Mamta Satoor <ms...@gmail.com>]

Hi Andy,

I am not sure what you mean by your application fails but here is some
general information about CLOB datatype in Derby. In Derby, CLOB
values are limited to a maximum of 2,147,483,647 characters. Derby
documentation on various datatypes can be found in Reference Manual at
http://db.apache.org/derby/manuals/index.html#docs_10.3

Mamta

On 4/14/08, Andy Rozman <an...@triera.net> wrote:
> Hi !
>
> I am new to derby and I have one question. I am using Hibernate with my
> application and I am having little problems with Derby... (I used same db
> configutaion on PostgreSQL, Mckoi and HsqlDb)...
>
> It seems that type text (which should be unlimited varchar) is interpreted
> as CLOB(255). I don't know where this happens but my application now
> fails... Is this Derby problem or Hibernate? I am using latest of Derby
> (10.3.2.1) and Hibernate 3.1.
>
> Which is longest varchar format in Derby?
>
> If someone uses Hibernate with Derby I would be thankful for any help...
>
> Andy
>

Re: derby & hibernate & type 'text'

[Damian Carey <ja...@gmail.com>]

On Tue, Apr 15, 2008 at 9:40 AM, Andy Rozman <an...@triera.net> wrote:
> Hi !
>  I am new to derby and I have one question. I am using Hibernate with my
> application and I am having little problems with Derby... (I used same db
> configutaion on PostgreSQL, Mckoi and HsqlDb)...
>  It seems that type text (which should be unlimited varchar) is interpreted
> as CLOB(255). I don't know where this happens but my application now
> fails... Is this Derby problem or Hibernate? I am using latest of Derby
> (10.3.2.1) and Hibernate 3.1.
>
>  Which is longest varchar format in Derby?
>  If someone uses Hibernate with Derby I would be thankful for any help...
>  Andy

We use both Derby and Postgres with Hibernate, so here are a few
ideas.  I guess your hibernate mapping is something like ...
<property name="nbString" type="text">
    <column name="nbString"/>
</property>

CLOB(255) is likely being set by the hibernate "Dialect". (Db2Dialect
I think ??)  The Postgres dialect can have the "text" type, which does
have a limit of around a gig. However Derby is different.  The longest
varchar in derby is 32672 long.  In hibernate you set it thus ...
<property name="nbString" type="string">
    <column name="nbString" length="32672"/>
</property>

Typically you are better off with the string in preference to the CLOB
because you can do more sophisticated text searches in a string than
in a clob. Of course it depends on what you are doing.

HTH
Cheers,
-Damian