HELP! * GREY=local LOCAL HTML version of Foils prepared July 6,1995

Foil 31 Using Oracle 7 Server's PCM locks:

From Explicit Examples in Parallel Relational Databases CPS600 Spring Semester -- April 1995. by Gang Cheng Marek Podgorny (Geoffrey Fox) * See also color IMAGE
An instance acquires a PCM lock as a resource for update purposes
All buffer caches must contain the same copy of a resource
PCM blocks:
  • Ensure cache coherency by only allowing instances to change blocks while holding a lock
  • PCM lock work independently of transaction locks (row-level locking)
  • Ensure cache coherency using minimum amount of communication
  • PCM locks are allocated to files when a instance is started
  • Blocks are typical O/S disk blocks and of fixed size

Northeast Parallel Architectures Center, Syracuse University, npac@npac.syr.edu

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