In 2001, I began pondering response time as it relates to firefighting. After all, what a user experiences is response time. So perhaps there was a way to approach Oracle performance analysis from a response-time perspective as well. It turned out capacity-planning response-time analysis could be applied to Oracle diagnosis. In fact, as I discussed in the previous chapter, it worked so well, I published the original paper on the subject. Since that time, there have been many different publications, tools, and products that embrace ORTA.

Since the introduction of Oracle 7, the most significant performance analysis improvement was released around 2005 with Oracle Database 10g. The active session history facility, known as ASH, provides a kernel-level data-collection facility. The fact that the collection ability resides directly in Oracle's kernel provides a number of significant benefits:

* Data collection can be intrusive, but since the collection is built directly into the kernel, the impact is minimized.