The Step Metrics tab

For each step in the Transformation, the Step Metrics tab shows several status and information columns. For now, the most relevant columns in this tab are:

To better understand the content of the Read and Written columns, let's explain them with an example. As said in the previous chapter, data flows from one step to other (or others). In our sample Transformation, data is read from a file and flows toward the Calculator step, the Number range step, and the UDJE step, in that exact order. The Step Metrics column allows us to see the number of rows that effectively flowed in that way. For example look at the Calculator row in the screenshot Partial Preview of a Transformation. Three rows came from the previous step (we see it in the Read column), while, due to the error in the third row, only two rows left toward the Number range step (this is visible in Written column). This also explains the difference between the two previews that we ran:

1. The preview on the UDJE step didn't show up any data. The error occurred before any row could reach this step. We can see it in the UDJE row in the Step Metrics tab.
2. The preview on the Calculator step showed only those two rows that left the step (those that count for the Written column).