Hi,


It is known that session factories are 'heavy' objects in terms of the overhead required for their initialization.

Nevertheless, there might be reasons to have multiple session factories within one application, such as:

• Requiring access to different databases from within the same application
• Requiring different naming conventions or other configuration options
  for different parts of the application
• Managabiliity: the application (which uses Hibernate) uses third party
  products that also use hibernate. Having one session factory per
  product makes it easy to manage the persistence configurations for
  these products independently. Here independent session factories are
  possible since the products communicate with each other exclusively
  through APIs and not through the database.

Now my question is. What is the overhead of having multiple session factories instead of one in terms of processing (CPU) and memory?

Cheers
Erik[/list]

dependent on how many mappings and data you have.

but is it just like an extra sessionfactory, so if you create 10 sessionfactories from the same configuration you will use 10 times more memory to keep those instances in the air.

multiple sessionfactories does not affect CPU time except the extra time you need to create them.

So in other words, if I have for example 20 classes of which the first 10 are mapped independently of the other 10, then having two session factories has a negligible overhead compared to only one?

well as a i said you will use twice the memory, but that is at least constant.