This article will help you:
In its basic form, Amplitude's group-by feature is a tool for categorizing events for aggregation. When you want to count the number of events by country, for example, you'd use a group-by:
Check out our Help Center article for a more detailed look at group-by visualization in Amplitude's Event Segmentation charts.
Pruning group-by results
For performance purposes, Amplitude sets a maximum limit on the number of groups a query result can return. When this limit is exceeded, the top groups are kept, while the rest are pruned from the query result. The top groups are determined in accordance with the table below.
With a single group-by in the Event Segmentation chart, results may be limited to 100 group-by results. For double group-bys, results may be limited to 500 group by results, in which each group by value pair is counted as a single result.
This table shows how Amplitude prioritizes group-bys for display in the Breakdown Table:
|Uniques||Number of Unique Users|
|Totals||Total Number of Events|
|% Active||Number of Unique Users|
|Average||Total Number of Events|
|Frequency||Number of Unique Users|
|Distribution of Property Value||Number of Unique Users|
|Sum of Property Value||Sum of Property Values|
|Average of Property Value||Sum of Property Values|
|Distinct Property Values Per User||Total Number of (User, Property Value) Pairs|
|Formulas: Percentile||Total Number of Events|
|Formulas: Frequency Percentile||Total Number of Events|
|Formulas: Property Count||Number of Unique Properties|
|Formulas: Property Count Average||Total Number of (User, Property) Pairs|
|Formulas: Default||Number of Unique Users|
NOTE: For formulas, this ordering will only be used if every metric in the formula uses the same ordering. Otherwise, the default formulas ordering will be used.