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Re: [eclipselink-users] EclipseLink @Lob Implementation DB Limitations 
Unfortunately DDL, especially for LOBs is not very well standardized across
different databases.  But your recommendation should be possible, please log
a bug.

The @Column size should be used when specified, and we should be able to
check if it is > the max varchar value and use a CLOB.  For MySQL we should
probably default mapping CLOB to LONGTEXT instead of TEXT.

A workaround may be to use a DescriptorCustomizer or SessionCustomizer to
set the mapping's field dynamically based on the platform.  Or use your own
scripts to generate or alter the schema.


drad wrote:
> 
> I am having an issue with EclipseLink related to LOBs (@Lob). Basically I
> have a sample project which has one class (Person) which has four columns
> (id, firstName, lastName, and datr). The datr column is defined as String
> with the @Lob annotation.
> 
> I have a JUnit test case which loads the above structure with varying size
> info in the datr column. I am using this to test writing large datasets
> into the created datastructure, currently the size varies from around 250
> characters up to 2mb of characters.
> 	
> In order to make this work for derby I discovered I needed to add a column
> definition (e.g. @Column(name="datr", columnDefinition="CLOB(5242880)")  
> //5242880=5mb -> provides for clobs up to 5mb.) annotation to the datr
> element. The next step in my testing was to switch to MySQL for the
> database and test the functionality there, wherein I discovered I needed
> to have a different column definition (e.g. @Column(name="datr",
> columnDefinition="LONGTEXT")   //provides for clobs up to 4294967295
> (4096mb).). 
> 	
> After searching goole I also discovered the length attribute to the
> @Column annotation and would expect this to solve the issue such as:
> 	if I specify a length of 5242880 I would expect the Persistence Provider
> to create the necessary sized Lob on the target db - if this is derby it
> would create a CLOB(5242880), if it is MySQL it would create a LONGTEXT.
> 		
> Am I wrong in expecting this to be one of the key uses of EclipseLink (and
> JPA)?
> 


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http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
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