Updates, Transactions

• It is unlikely that we can expect to guarantee transaction atomicity when updates at multiple sites are involved.

• Updates propagated asynchronously.

  • Semantic latency: Inconsistency due to updates that have not yet been propagated to all sites. (E.g., Acme’s new prices not yet reflected in Parts ‘R Us cache.)
  • What form of ACID semantics can we salvage? Alternative semantic foundations that deal with semantic latency?

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