Andrew McDonough

Please note: This page is imported from my wiki, which hasn't been updated in over 10 years. Some of the formatting was lost during the import. I'll try to get around to fixing it someday.

Database Theory

ACID Properties

ACID Properties are the key properties of transaction processing within a database. A transaction is usually a collection of one or more statements.

  • Atomicity - Transactions either occur (all queries commit) or don’t (rolled back executed queries reversed).
  • Consistency - All constraints of the database must be satisfied before and after a transaction.
  • Isolation - The transaction should be carried out without any other process being able to see the intermediate state.
  • Durability - After a transaction has committed, it’s effects should persist, even in the event of a database failure.


Andrew McDonough

Andrew McDonough is a consultant CTO and software developer, currently based between Berlin and London.

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