The User Flow report can generate large amounts of data, causing the browser to slow down and in some cases may even hang when trying to render the data. To mitigate such issues, several safeguards have been applied both from the reporting API as well as the User Interface.
The reporting API applies a limit of approximately 1,000 complete unique paths. If this limit is reached, it will reduce the data by decreasing the number of steps it returns. In order to analyze further steps, you may drill down on specific nodes by right clicking on them and selecting Explore paths through here.
NOTE: A complete path is one which contains the same number of nodes as the requested steps, so for example in a report showing 5 steps, a path is considered complete if it is made up of 5 nodes. Partial paths are not included in this limit and therefore the number of total paths returned will be much larger.
Nodes can be drilled down up to 21 steps. Nodes which fall after this limit will have the Explore paths through here option disabled.
Additionally, paths which contain repeating events are heavy to process and may take a very long time to complete. For this reason, nodes which contain paths with more than 7 of the same contiguous events cannot be drilled down further. If your chart contains an event which is continuously being repeated and thus causing noise, it is suggested to exclude it by right clicking on the node, select Add to exclude list and click on Apply Settings to re-generate the report.
Exclusion List Limit
When a path contains more than 25 contiguous events which are in the exclude list, at that point the path is not processed further and set to end at System: Others. For example let's say I have event X and event Y in the exclude list:
A -> B -> C -> X * 30 -> D -> B -> C
This path has 30 contiguous event X and will result in:
A -> B -> C -> System: Others
A -> B -> C -> (X -> Y) * 15 -> D -> C
This path has 30 contiguous events X -> Y and will result in:
A -> B -> C -> System: Others
A -> B -> C -> X * 10 -> D -> B -> Y * 10 -> C
This path does not have more than 25 contiguous noise events and will result in:
A -> B -> C -> D -> B -> C
The User Flow report has a timeout limit of 90 seconds. If a request takes longer to be processed, it is cancelled and a warning is displayed accordingly. The time it takes to process a request depends on various factors, including the size of the data, the number of events that are excluded and current load on the server. In case of a timeout, re-trying the request at a less busier time may help in processing it within the time limit.
Interactive Mode Warning
Switching the chart to Interactive Mode means that each individual path is processed and displayed separately. When the User Interface detects that a chart will contain a large number of links if it is switched to Interactive Mode, a warning will be shown to indicate that rendering such chart may take a long time and cause the browser to slow down. In extreme cases proceeding to Interactive Mode may cause the browser to hang.
This warning may also be displayed if drilling down on a node when the chart is already in Interactive Mode.
More information about the User Flow report can be found in this KBase article.