A beginner’s guide to read and write skew phenomena


In my article about ACID and database transactions, I introduced the three phenomena described by the SQL standard:

  • dirty read
  • non-repeatable read
  • phantom read

While these are good to differentiate the four isolation levels (Read Uncommitted, Read Committed, Repeatable Read and Serializable), in reality, there are more phenomena to take into consideration as well. The 1995 paper (A Critique of ANSI SQL Isolation Levels) introduces the other phenomena that are omitted from the standard specification.

In my High-Performance Java Persistence book, I decided to insist on the Transaction chapter as it is very important for both data-access effectiveness and efficiency.

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