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Pattern: Transaction log tailing


You have applied the Saga pattern. In order to be reliable, services must atomically publish events whenever their state changes. It is not viable to use a distributed transaction that spans the database and the message broker.


How to reliably/atomically publish events whenever state changes?


  • 2PC is not an option


Tail the database transaction log and publish each change as an event.


Resulting context

This pattern has the following benefits:

  • No 2PC
  • No application changes required
  • Guaranteed to be accurate

This pattern has the following drawbacks:

  • Relatively obscure
  • Database specific solutions
  • Tricky to avoid duplicate publishing
  • Low level DB changes make difficult to determine the business level events

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