We’re looking at 4 general types of functions here: rollup functions, aggregate functions, transformation functions, and label manipulation functions. The engine pulls all time series named http_requests_total within the given time range from the metrics storage Converts the instant vector http_requests_total to last_over_time(http_requests_total[lookback]) (in Prometheus) or default_rollup(http_requests_total[lookback]) (in VictoriaMetrics) Evaluates the last_over_time() or default_rollup() function at each timestamp to produce a full set of data points from 00:00:00 to 23:00:00 Applies the aggregation function sum() at each timestamp to group the values by service In earlier examples, we used a rollup function like rate() on a range vector, and then applied an aggregation function like…