Using Spring's property-placeholder

With Spring it becomes necessary to configure our beans. This at times involves setting sensitive information in our XML files. In case of database connectivity it would be a username or password. People are not comfortable with this kind of details being available in their war files.

Publishing Events asynchronously

In the previous post we saw how Spring's ApplicationContext provided for event publishing and listening. The default listener that Spring implements is synchronous. The publish method will wait until the methods of all the listeners have completed successfully. This kind of blocking behaviour may not be suitable for all scenarios.

fetch = join for Collection

There could be a scenario wherein we need an association to be always available whenever an Entity is loaded. In this case the additional select queries that are fired are a performance loss. We could tell Hibernate to fetch the entity and the association in a single call to the database.

fetch = subselect

We have seen that the default fetch strategy for lazy Collections can result in an N+1 problem. We saw how to improve this using the batch size setting. Here also however the query count can end up being a little high.
Hibernate also allows all the Collections to be retrieved in a single query when a single collection is accessed. Thus as opposed to a reduced query count that we get via batching, in this case it is exactly 1 additional query.

batch-size =n

In our previous example we saw how a default fetch strategy(fetch = "select") could result in N+1 selection problem for Hibernate Associations. One way to solve this problem would be to use batch-size property