The collectionTime attribute is the time at which the metric was collected.

Why does it matter ?

Based on it, we can compute the delta in second between 2 collections.

Let’s see two use cases.

First use case: Suppose, you decided to extract real-time metrics from the cumulative ones. To do so, you created a script that takes a snapshot of the cumulative metrics each second (default interval) and computes the delta with the previous snapshot (yes, I am describing my exadata_metrics.pl script introduced into this post 🙂 ).

Then, if the delta value of the metric is 0, you need to know why (two explanations are possible as we’ll see).

Let’s see an example: I’ll take a snapshot with a 40 seconds interval of 2 IORM cumulative metrics: