Thursday, April 09, 2015

Oracle Calendar Migration to #MSFTExchange @Office365 Recurrence Patterns

The question came in: "Which recurrence patterns migrate from Oracle Calendar Server to Exchange?"

The short answer to this is that NONE of them MIGRATE – our technology RECREATES them.
Oracle strips every recurrence pattern out of ICS exports in part because Outlook cannot handle the patterns OCS can produce.
Sumatra technology analyzes these patterns and produces the best matches it can for recurrences.

A couple of rules in this:

  • THE WORST CASE is all the data goes in as one-time events or meetings.  You do NOT lose data.
  • You need at least 5 instances before we try to form a pattern recreation
  • We look for exceptions with a 80% regularity by default  (you can change this – but do not screw with it yet)

The patterns most likely to get picked up and transferred:

  • Every 15th (for example) Day of the Month
  • Every 2nd Wednesday (for example) of the Month
  • Every MTWTF and variations of that, e.g., TuTh, MWF. etc.
  • Weekly meetings / every other week / every fourth week
  • Yearly meetings

Over the last 15 years of doing this kind of migration – this is over  90% of recurrences in most environments

The patterns that are not going to get re-created as patterns:

  • Random selections of dates
  • Every 1st AND 3rd Friday of the Month  (sometimes with enough exceptions and a forgiving exception rate these will show up as “every other week” recurrences, but do not count on it)
  • ANY recurrence with LOTS of exceptions.  I.e., over 20% 

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