## Notes The *PACELC Theorem* is an extension of the [[CAP Theorem]]. In fact, the *CAP Theorem* encompasses the "PAC" in the *PACELC Theorem*. The other *ELC* describes the trade off when no network partition occurs, then the system must decide between *Latency* and *Consistency*. ## Latency *Latency* occurs when a distributed system is wholly interconnected because all nodes in the cluster must have the same state. To achieve that same state, the system must communicate the updates to all of the relevant nodes. A system can take longer to respond to updates in order to make sure that all nodes have the same state. Otherwise a system can choose to prioritize eventual consistency in order to respond to updating requests quicker. ## Consistency *Consistency* describes the situation when the nodes in the cluster are at the same state.