Metadata Support (Reference)

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Subscription information is stored in a new system relation RDB$SUBSCRIPTIONS with a unique key on RDB$SUBSCRIPTION_NAME, RDB$SUBSCRIBER_NAME, RDB$DESTINATION. Additional fields store control information to facilitate "check in" and "check out" of changed data. This includes transaction IDs, timestamps and transactional context of last observation of changed data on the schema object.

  • The term "check out" denotes SELECT of changed columns of rows from subscribed tables when a subscription has been activated.
  • The term "check in" refers to INSERT, UPDATE and DELETE of changed columns of rows from subscribed tables when a subscription has been activated.
  • A subscription becomes activated during a database session with the execution of SET SUBSCRIPTION ACTIVE.
  • It is deactivated with the execution of SET SUBSCRIPTION INACTIVE.

RDB$SUBSCRIPTION and RDB$SUBSCRIBERS are new tables covering the subscription/subscriber elements. The other tables listed show columns that have been updated or added to an existing table.

For more information on the new and updated columns for the implementation of the Change View feature see Metadata Support.

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