Event Ordering for Identical Timestamps

This article contains information how define the order of events correctly in situations where there are identical timestamps within the same cases.

Overview

The order in which events occur within a case is important in process mining, because the ordering is visualized for example in flowcharts. Also changing the order means that the case belongs to different variation. The order of events comes naturally from event timestamps which are always in the eventlog data. There is still one exception, when there are events that have the same timestamp within a same case, the eventlog data cannot reveal the order in which the events occurred. In many eventlogs, events with exactly identical timestamps is quite rare, but it may occur more often in following circumstances:

• There is a system that processes several events at the same time and records the events using the same timestamps.
• Accurate timestamp are not available (such as in millisecond level), but for example only the date is available. In this situation, all events that occurred within the same day, have the same timestamps

If the order is events is known, it's possible to set them in the defined order as explained below.

Event Order in QPR ProcessAnalyzer

In QPR ProcessAnalyzer, the ordering of events with identical timestamps within the same case always the same as in the eventlog data. In practise, if the model uses a datatable for events, the order of rows in the datatable determines the order of those kind of events. Thus, if the order is a concern, make sure to order the data in a desired order in the datatable, when new data is imported to the datatable.

This same logic also applies for models, that get their data from an ODBC datasource or from a loading script.

Eventlog Sorting Example

This example script sorts rows in an events datatable based on the defined sort order. Event order starting from the first is: Delivery planned, Invoice sent, Payment received. Other event types are equal. The script reads the datatable to a temporary table to the scripting database, and writes the data back after sorting it.

(SELECT 'AnalysisType', '18') UNION ALL 
(SELECT 'ProjectName', 'MyProject') UNION ALL
(SELECT 'DataTableName', 'MyModel events') UNION ALL 
(SELECT 'TargetTable', '#EventsTemp')
(SELECT 'MaximumCount', '0') UNION ALL
--#GetAnalysis

(SELECT 'ProjectName', 'MyProject') UNION ALL
(SELECT 'DataTableName', 'MyModel events') UNION ALL
(SELECT 'Append', '0');

SELECT *
FROM #EventsTemp
ORDER BY
[CaseId],
[EventTimestamp],
(CASE [EventType]   
WHEN 'Delivery planned' THEN 1
WHEN 'Invoice sent' THEN 2
WHEN 'Payment received' THEN 3
ELSE 4 END)
--#ImportDataTable