Hi,

Does anyone know the best hibernate type to use when mapping from a Java String to a db charater field, larger than 1 in length, in the hbm file.

We have been using <column name="code" sql-type="char(3)"/>
up to now but would prefer to use a hibernate type field instead.

i.e. <property name="code" type="?"

Thanks,
Nick..

Hi Nick,
you are overiding the default mapping of Hibernate type to SQL datatype.

If you have a char more then 1 character length and you do not want to override the Hibernate mapping
then use type="string"

<column name="code" type="string"/>

or


<column name="code" /> in case the java type of the code is java.lang.String

I may have missed the point; please let me know about your thoughts

Thanks

Hi Alan,

Thanks for your answer. I wasn't sure whether it was string or there was another hibernate type to use. I know there is a charater type, but this is just for char 1.
Do you know why it would be a good idea to use sql-type? It looks like there are enough hibernate types to cover most instances?

Thanks,
Nick..

Nick,
Yes hibernate types coverse most SQL type.


Well, it depends on you database design and requirements.
Sometimes you need char(3) and not varchar(3) so you overide the hibernate definition type for string by
saying

<column name="code" sql-type="char(3)"/>

instead of

<column name="code" type="string" length="3" />

since you are aware that the variable will be of a constant lenght of 3 and not a variable of max length of 3. Char(3) is more optimized for speed and Varchar(3) is more optimized for storage.


or if your database provider uses a datatype called currency and you do not want to use hibernate currency type which maps to VARCHAR

I do not think there are fix rules but rather a design related approach.

Cheers

Hi Alan,

I have a char(3) field. So for performance wise do you recommend I use a sql-type=char(3) rather than using a hibernate type of string? I was under the impression that it was better to use the hibernate types and their performance was good?

Nick..

Nick,
I am trying to say if you know that char(3) is needed and not varchar(3) then for the database which tries to retrieve the value or insert it, it is more optimized (constant better then variable). Now hibernate execute the query to make the insertion to the database so the datbase does the job to persist the data. I am not sure if Hibernate does more work when it overrides the default mapping definition.


Cheers

Nick,
I am trying to say if you know that char(3) is needed and not varchar(3) then for the database which tries to retrieve the value or insert it, it is more optimized (constant better then variable). Now hibernate execute the query to make the insertion to the database so the datbase does the job to persist the data. I am not sure if Hibernate does more work when it overrides the default mapping definition.


Cheers

Nick,
I am trying to say if you know that char(3) is needed and not varchar(3) then for the database which tries to retrieve the value or insert it, it is more optimized (constant better then variable). Now hibernate execute the query to make the insertion to the database so the datbase does the job to persist the data. I am not sure if Hibernate does more work when it overrides the default mapping definition.


Cheers

Yeah I guess, thats what I really need to find out. Why use sql-type. What advantage does this give. Why use it. Does it increase or hinder performance.