One of the most overlooked features of Java and programming generally, is WeakReferences. Here you can find a walkthrough of java.lang.ref and similar options in other languages with suggestions of possible uses.
When choosing a DMBS for your project, you will find many DBMS with different performance tradeoffs. A wise decision should be based on the use case that you are interested in, some projects need to scale up for millions of users and it would do care for response time to serve one of these users. Other projects may be limited to small number of users who will perform heavy queries for generating detailed reports.
In this post we will discuss some use cases that seem to be common in many different systems, and we will conclude why or why not to use a specific DBMS for each use case:
In one of the Mac OS X projects we were working one, We needed to get memory usage attributes that appears in Mavericks Activity Monitor.