introduction to nosql consistent again in one node the data might say "aand in the other it might say "bbecause it was adapted laterat conflict resolution when the network is back onlineit' possible the "ain the first node is replaced by " even though no one did anything to explicitly change "ainto " ,it will take on this value as it becomes consistent with the other node eventual consistency--the database will become consistent over time in the web shop examplethe table is sold twicewhich results in data inconsistency once the connection between the individual nodes is reestablishedthey'll communicate and decide how to resolve it this conflict can be resolvedfor exampleon first-comefirst-served basis or by preferring the customer who would incur the lowest transport cost databases come with default behaviorbut given that there' an actual business decision to make herethis behavior can be overwritten even if the connection is up and runninglatencies might cause nodes to become inconsistent oftenproducts are kept in an online shopping basketbut putting an item in basket doesn' lock it for other users if fritz beats freddy to the checkout buttonthere'll be problem once freddy goes to check out this can easily be explained to the customerhe was too late but what if both press the checkout button at the exact same millisecond and both sales happenacid versus base the base principles are somewhat contrived to fit acid and base from chemistryan acid is fluid with low ph value base is the opposite and has high ph value we won' go into the chemistry details herebut figure shows mnemonic to those familiar with the chemistry equivalents of acid and base acid base atomicity consistency isolation durability basically available soft state eventual consistency figure acid versus basetraditional relational databases versus most nosql databases the names are derived from the chemistry concept of the ph scale ph value below is acidichigher than is base on this scaleyour average surface water fluctuates between and