MongoDB applied design patterns – Ch. 3


Chapter3 – ‘Mimicking tx behaviour’

“One of the goals of the RDBMS normalisation is the ability to make atomic changes to a single row…Although normalisation goes a long way towards such consistency enforcement, there are some types of consistency requirements that are difficult or impossible to express in a single SQL statement. Some examples:

  • Deleting a row in a 1:M relationship eg deleting an order should also delete its subordinate ‘line-item’ rows
  • Adjusting the quantity of a line-item on an order should update the order total cost (assuming that cost is stored in the order row itself)

The chapter then goes on to consider RDBMS COMMIT and ROLLBACK operations and how these are impacted/copied in a distributed (multi-server) environment, including complex and/or optimistic update approaches


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