Bitcoin siteleri extend this useful metaphor further, let’s first look at the idea of pH. Søren Peder Lauritz Sørensen first developed the concept while working at the Carlsberg Laboratory in 1909, so the idea is not something new.
ACID requirement in place within a given system, reliability was suspect. If one element of a transaction fails the entire transaction fails. Consistency: The transaction must meet all protocols or rules defined by the system at all times. Isolation: No transaction has access to any other transaction that is in an intermediate or unfinished state.
Thus, each transaction is independent unto itself. This is required for both performance and consistency of transactions within a database. There are of course many facets to those definitions and within the actual ACID requirement of each particular database, but overall in the RDBMS world, ACID is overlord and without ACID reliability is uncertain. In 2000, Eric Brewer presented his keynote speech at the ACM Symposium on the Principles of Distributed Computing and CAP Theorem was born. PCs to work, the Internet to work, social media to work, all with consistent availability to their files. Consistency refers to whether a system operates fully or not.