Qlik Replicate: Daylight Savings Guidance

[KellyHobson]

Daylight Savings Time occurs two times per calendar year in the spring (DST On) and in the fall (DST Off) in participating countries. Below is a condensed version of our Qlik Replicate User Guide best practices for administrators who are managing Replicate task during time change.

DST On (Spring forward): Local time is moved one hour forward (i.e. 2:00 AM becomes 3:00 AM)

DST On change does not impact Qlik Replicate because it does not result in time overlap.

DST Off (Fall back): Local time is moved back one hour (i.e. 02:00 AM becomes 01:00 AM).

DST Off change results in time overlap where local time travels over the same hour twice in a row.

Since Replicate Server uses UTC time, tasks do not depend on time zone or DST for properly scanning the transaction logs. Thus there are no preliminary steps which need to be taken before DST events. 

That being said, here are best practices to avoid issues during a time change:

1. Do not schedule Replicate tasks to start during the time change window
   
   Example DST On: Do not schedule a task to run 2:00 AM to 2:59 AM as this time does not exist
   
   
   
   Example DST Off: Do not schedule to run 1:00am to 1:59am as the job will run twice
   
   
   
   
2. Task with initial full load or reloading of tables should NOT be done during the DST change window. Tasks that move from Full Load to Change Processing when DST comes into effect may encounter data loss.
   
   
3. You may experience one hour of latency in a task or a time discrepancy during DST Off. In this case, we recommend to stop/resume the individual task or stop/start of Qlik Replicate services which will act as a stop/resume on all tasks.  Note, handling of this behavior was already submitted as an ideation request.

For additional reading and guidance, please check out the User Guide section on DST.

Additional reference: You can check your Server local time vs UTC time within the Server tab -> Scheduling -> New Scheduled Job window.   On my environment, my local time is EST time.

Environment

Qlik Replicate 

The information in this article is provided as-is and to be used at own discretion. Depending on tool(s) used, customization(s), and/or other factors ongoing support on the solution below may not be provided by Qlik Support.