This example describes how to use the following rolling computational functions:

• ROLLINGKTHLARGEST - computes the kth largest value from a rolling window of rows before and after the current row. Duplicate values are treated as having the same k values. See ROLLINGKTHLARGEST Function.
• ROLLINGKTHLARGESTUNIQUE - computes the unique kth largest value from a rolling window of rows before and after the current row. Duplicate values are treated as having different k values. See ROLLINGKTHLARGESTUNIQUE Function.

The following dataset contains daily counts of server restarts across three servers over the preceding week. High server restart counts can indicate poor server health. In this example, you are interested in knowing for each server the rolling highest and second highest count of restarts per server over the previous week.

Source:

Transformation:

First, you want to maintain the row information as a separate column. Since data is ordered already by the Date column, you can use the following:

Use the following function to compute the rolling kth largest value of server restarts per server over the previous week. In this case, you can use the ROLLINGKTHLARGEST function, setting k=1. Uniqueness doesn't matter for calculating the highest value:

Use the following function to compute the rolling second highest value. In this case, you can use ROLLINGKTHLARGESTUNIQUE: 

Results: