Lock Manager Implementation

• Question 1: What are we locking?

  • Tuples, pages, or tables?
  • Finer granularity increases concurrency, but also increases locking overhead.

• Question 2: How do you “lock” something??

• Lock Table: A hash table of Lock Entries.

  • Lock Entry:
    • OID
    • Mode
    • List: Xacts holding lock
    • List: Wait Queue

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