"current session" for multitenant application?

Tom31 · **Joined:** Mon Jul 28, 2014 9:18 am **Posts:** 6

We developped several multitenant Java web applications. The multitenancy model was "database per tenant", meaning that each tenant has its own database. Actually for the webapp each tenant is seen as a distinct JDBC datasource, so the model is more like "datasource per tenant".

Each time we faced the same requirement: being able to read or write data from multiple tenants within the same transaction (for example to display in a single web page stats about all the tenants, or to change some access rights for multiple tenants at once). This means that during a single web request, we have to be able to use multiple sessions of the same session factory.

I think the Hibernate 4.1.12 implementations of "current session" do not support this "sessions switching":

ThreadLocalSessionContext

ManagedSessionContext

JTASessionContext

So we had to implement our own CurrentSessionContext.

My question is: does Hibernate support, out of the box, using multiple sessions from the same session factory during a single web request? If yes, how?

Thank you for your time.

emmanuel · **Posted:** Wed Apr 29, 2015 7:38 am

Is you code relying on

Code:

SessionFactory.getCurrentSession()

?
Because if you explicitly set an tenant id, the classes you mention should not have to be invoked I think.

Code:

Session session1 = sessionFactory.withOptions()
        .tenantIdentifier( tenant1 )
        ...
        .openSession();
Session session2 = sessionFactory.withOptions()
        .tenantIdentifier( tenant2 )
        ...
        .openSession();

//have fun with session1 and session2

Is that what is not working?

Tom31 · **Joined:** Mon Jul 28, 2014 9:18 am **Posts:** 6

I'm not sure I correctly understood your point. :)

I'd like to keep the "currentSession()" mechanism to reuse sessions from the same web request, because explicit calls to "openSession()" will create new sessions.

I'd need something such as:

Code:

// Beginning of web request

[In myBusinessService] sessionFactory.setCurrentTenantIdentifier("tenant1"); // or something that sets the current tenant ID
[In myDao] sessionFactory.currentSession().doSomething();

[In myBusinessService] sessionFactory.setCurrentTenantIdentifier("tenant2"); // or something that sets the current tenant ID
[In myDao] sessionFactory.currentSession().doSomething();

// Possibly work again with tenant1 and/or tenant2

// End of web request

Is this pattern supported ?

emmanuel · **Posted:** Thu Apr 30, 2015 9:16 am

Ok got it now, no it's not supported.

Code:

sessionFactory.setCurrentTenantIdentifier("tenant1");

would be a bad approach as it does not necessary make this thread safe but one could imagine a

Code:

CurrentTenantIdentifierResolver

implementation that returns the right tenant id based on some user input.

I have opened https://hibernate.atlassian.net/browse/HHH-9766 to discuss this.

Tom31 · **Joined:** Mon Jul 28, 2014 9:18 am **Posts:** 6

Ok, thank you for your answer and for the feature request. :)

Tom31 · **Joined:** Mon Jul 28, 2014 9:18 am **Posts:** 6

I think using multiple sessions (being tied to a multiple tenants) from the SAME session factory is in fact doomed to fail, as it does not support second second level caching (and also session factory stats).

More precisely considering that the second level cache is at the session factory level, I think data cached on behalf of one tenant would be visible to other tenants, hence breaking the isolation of the tenants.

Can you confirm my explanation ?

If confirmed, you can remove the feature request for me because the caching issue is a too important limitation.

As a consequence each tenant must have its own session factory, and the present Hibernate implementations of "current session" are enough to support the uses cases I mentioned in my first post.