In this post, we will describe the Primary Component, a central concept in how Galera ensures that there is no opportunity for database inconsistency or divergence between the nodes in case of a network split.
What is the Primary Component?
The Primary Component is that set of Galera nodes that can communicate with each other over the network and contains the majority of the nodes. In case of a network partition, it is those nodes that can safely commit a transaction. A cluster can only have one such set of nodes, as there can only be one majority. No other set of nodes will commit transactions, thus removing the possibility of …[Read more...]