DOORS modules take longer to save when DCNs are enabled

Answer

IBM Rational DOORS modules take longer to save when Data Change Notifications (DCNs) are enabled because when you have DCNs enabled, they require time to create and process.

As of DOORS 9.5.2, due to the APAR PM88224 fix, if DCNs are enabled, it has to create 100 DCNs before deciding that it should simply treat the entire module as changed, so a module save will take longer than if DCNs were not enabled. In addition, it gets slower as the number of changes increases because even though it stops adding new DCNs, it still has to update the existing module once for each object that has changed (to maintain the last changed time, and more).

For example, if you test with a 4000 object module in various configurations, your average save times will be similar to this:

• DCN Disabled: 3 seconds
  
  
• DCN Enabled in DOORS 9.4 and later, prior to 9.5.2: 2 minutes 45 seconds
  
  
• DCN Enabled in 9.5.2 and later: 36 seconds

Please note that even with the 9.5.2 performance enhancements, module saves with DCNs enabled will still take about 12 times longer to complete than if DCNs were disabled. If you are interested in requesting that module save performance be improved further, please vote request for enhancement (RFE) #52816 at the IBM RFE Community.

Since module save times will always be slower with DCNs enabled than they will be with DCNs disabled, we recommend you disable DCNs unless you need to have them enabled.