問題文
A chart shows one hundred hosts divided among ten services. The engineer applies the mean function as an aggregation with a group-by on the service dimension. What appears on the chart, and what is the requirement for the group-by to work?
選択肢
- One hundred lines appear, one per host, because a group-by preserves the individual series and only labels them with the group name for use in the legend and the data table.
- One line appears showing the mean of the ten service means, because the group-by determines how the intermediate values are computed before the final aggregation collapses all of them into one output series.
- Ten lines appear only if the service information is a tag; tags are the metadata kind that the group-by menu reads when it builds its list of choices.
- Ten lines appear, one per service, each showing the mean across the hosts of that service; the group-by works when the service is a dimension or a property, and does not work when it is only a tag.