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Coming Soon: Data Rollups

Last updated October 2020

What's changing and why?

In order to get you the data you want faster, we've changed our data storage schema that powers the Metrics API to use roll-ups instead of only raw event data. Data roll-ups is a common method of compressing and pre-aggregating historic data which helps improve overall user performance and response times. We will continue performing real-time aggregation on raw event data for up to the minute reporting.

Most users of the UI or Metrics API will not notice differences in results. In fact there will be  significant performance improvements, especially for our highest volume customers and when looking at reports that span multiple months. However, this update does mean that some of the detailed results may change in the ways set out below.

What will be different?

Aside from the faster load times, there are a few small changes you may notice:

Time Zone

In an API call, timezone will only be respected when precision is hour or less. API calls where precision is day, week, or month will always return UTC time. An API call with a precision of  day or above that also includes a timezone will still succeed, but the results will be returned in UTC rather than the timezone included in the request.

In the UI, the new Timezone selector will only let you change the timezone when the Precision selector is set for hour or less. The UI will always display in UTC when the Precision selector is set for day, week, or month. If you want to change the Timezone selector but can't, please first change the Precision selector to hour or less.

"Unique" Metrics

The raw data is pre-aggregated into minute, hour, and day increments, which are used to support the various precision options:

PrecisionRoll-up Increment

This means that at some precisions, engagement events that occurred within the same precision period but in different roll-up increments cannot be deduped. This can slightly inflate "unique" metrics. Our analysis indicated that this inflation was 3-4% at most.

In both the API and the UI, unique clicks and unique opens will report the unique events that occurred during the roll-up increment. At precisions that do not strictly align with roll-up increments, uniques may be slightly inflated.

Example: Recipient opens an email at 1:08pm, 1:13pm, and 2:37pm.

  • At 1min precision, these events will be reported as 3 separate "unique" opens, each within the minute they occured.
  • At 5min precision, these events will be reported as 3 separate "unique" opens, 1 during 1:05-1:09, 1 during 1:10-1:14, and 1 during 2:35-2:40.
  • At 15min precision, these events will be reported as 3 separate "unique" opens, 2 during 1:00-1:14 and 1 during 2:30-2:44. This is because 15min precision is using 15 individual one-minute roll-up increments, and the opens cannot be deduped across the different roll-up increments.
  • At hour precision, these events will show up as 2 separate "unique" opens, 1 during 1:00-1:59 and 1 during 2:00-2:59.
  • At day precision, these events will show up as 1 "unique" open for the day.

In the UI, the name of the metric will change to show the period being used for the unique values.

Example: Unique Clicks per hour

Time frame rounding on the Time Series API endpoint

When the time frame selected does not match the precision selected in the time series endpoint, the response will round to the closest time frame that matches the precision.

Example: Time series request for 3:12pm - 3:28pm at 5 minute precision.

Previously, the API would return the following buckets:

  • 3:12:00-3:14:59
  • 3:15:00-3:19:59
  • 3:20:00-3:24:59
  • 3:25:00-3:29:59

Now, the API will return the following buckets:

  • 3:10:00-3:14:59
  • 3:15:00-3:19:59
  • 3:20:00-3:24:59
  • 3:25:00-3:29:59

This rounding method is already used by the aggregate endpoints and the UI, so the experience will be more consistent.

Deliveries by Attempt grouping

The deliveries by attempt endpoint will group attempts that are 3 or greater into a single value.  96% of deliveries are made on the 1st or 2nd attempt, so the additional granularity above 3 attempts is generally not valuable.


Previously, the API would return the following:


Now, the API will return:


The UI already groups delivery attempts into "Delivered 1st Attempt" and "Delivered 2+ Attempts" so there is no change to the UI.

As always, reach out to us if you have any questions or concerns. You can contact your Technical Account Manager directly or submit a support ticket in the app (EU) and we'll be happy to assist.

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