Why NoSQL is better at “scaling out” than RDBMS?

Question

I have read the following text in a technical blog discussing the advantages and disadvantages of NoSQL

\" For years, in order to improve performanc

Answer 1

Typical RDBMSs make strong guaranties about consistency. This requires to some extend communication between nodes for every transaction. This limites the ability to scale out, because more nodes means more communication

NoSql systems make different trade offs. For example they don't guarantee that a second session will see immediately data commited by a first session. Thereby decoupling the transaction of storing some data from the process of making that data available for every user. Google "eventually consistent". So a single transaction doesn't need to wait for any (or for much less) inter node communication. Therefore they are able to utilize a large amount of nodes much more easily.