Did you use window functions?

In Go, window functions as in SQL are absent, as this is a concept related to data processing in relational databases.

However, if the question concerns using window functions in the context of working with databases from Go, then usually SQL queries with window functions are used, which are executed on the DBMS side, with Go acting as a client.

Example of using a window function in SQL through Go:

query := `
  SELECT id, value, 
         ROW_NUMBER() OVER (PARTITION BY category ORDER BY value DESC) as rank
  FROM items
`
rows, err := db.Query(query)
// process results

If the question is about implementing window calculations directly in Go, then usually custom functions are written that slide over slices with the required window, for example, for a moving average:

func movingAverage(data []float64, window int) []float64 {
    if window <= 0 || window > len(data) {
        return nil
    }
    result := make([]float64, len(data)-window+1)
    var sum float64
    for i := 0; i < window; i++ {
        sum += data[i]
    }
    result[0] = sum / float64(window)
    for i := window; i < len(data); i++ {
        sum += data[i] - data[i-window]
        result[i-window+1] = sum / float64(window)
    }
    return result
}

Thus, Go does not have built-in window functions, but they can be used via SQL or implemented manually for data processing.