This presentation examines remote and distributed queries and transactions over database links.
The problem of multiple transaction branches involving RAC database instances are discussed followed by Oracle Single Phase and Two Phase commit processing over DB Links including:
Prepare, Response to Prepare, Commit/Rollback and Forget phases. It is followed by a discussion of two phase commit in-doubt failures and resolution using the Recoverer Process (RECO) or DBA manual resolution.
Finally, the implications of Point in Time Recovery on Distributed Databases is examined.