How do I get a Cloudwatch bar chart to group by period?

Hi, and thank you for reaching out!

Currently, bar charts graphed in CloudWatch Metrics cannot display data over time broken up by the specified period. The Bar chart option is intended to graph data categorically as opposed to chronologically. As a result, specifying the Bar chart option for a metric will aggregate all the data within the specified time range in to a single bar per metric. In order to view metric data as a time-ordered graph, you will need to use the Line or Stacked Area options at this time.

I can confirm that there is an open feature request to allow for a time ordered histogram when graphing metrics. While I am unable to comment on if/when this feature may get released, you can keep an eye on our What's New and Blog pages for any new feature announcements!