Hi
To give you a big picture on my problem let me explain this example:
we have a table for keeping address parts and a corresponding entity:

Address: street_line1, street_line2, city, country, number, phone_number

now we want that if the user needs an extra field she simply add that field,
for example an emergency_phone_number. in this case, the user defines
another field and she type the name of the field and then its value.

We're developing a large scaled banking application and these fields are not
as easy as the address fields and they are really significant in our
application. one table may have between 5 to 15 dynamic fields and there are
lots of tables

One way is to define a number of fields as RESERVED fields but this enlarge
our tables with lots of NULL values and in each select statement the ORM
will select all of them

Another way is to place them in another table with a one-to-many
relationship but this has some drawbacks. we can't load them lazily because
we don't know if there is any dynamic field or not so we have to always join
them and set it as EAGER so each table has another extra sql join that
affects the performance which is very important for a banking system.

I am eager to know your idea and your experience in this matter and how to
encounter them in our entities with JPA.




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Regards
Mohammad
http://pixelshot.wordpress.com Pixelshot 
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