Design Requirements

AutoPatch was designed with a few very simple requirements in mind.

• Patches should execute before any server logic
  • This is important, or the application logic couldn't trust the state of the external systems
• AutoPatch must enforce a total natural ordering on all patches.
  • This allows a developer to depend on the results of previous patches, for instance a patch can use database tables defined in patches that were executed previously
• AutoPatch must ensure that each patch is applied once and only once
  • Having them apply multiple times would mean the patch author could never trust the initial state of the database, making patch development very difficult
• AutoPatch should be able to globally order patches that execute against multiple external systems
• AutoPatch should be capable of executing post-patching maintenance after patching (things like recompiling pl/sql, etc)
• AutoPatch should be capable of executing the same patch across multiple databases with the same schema
• AutoPatch should be capable of running in a read only way, showing what it would do, but not changing anything
• AutoPatch should be able to support multiple migration strategies.
  • Developers could be able to add their own migration strategy to AutoPatch.