Difference Between Global and Local ordering

Question

 

 As a result, all retrieval APIs offer a choice between global (the default) or local ordering. Global ordering guarantees that, once the chain has reached consensus, all nodes receive the same responses from the same API calls. Local ordering guarantees that, for any particular node, the ordering of a stream’s items will never change between API calls. 

 

I don't understand what is ment by the above text. Does global ordering of stream items mean that the ordering is different on various nodes? The global ordering is saying something about the responses are the same when retrieved. The second sentence says something about the ordering of streams, which are completely different from responses?

 

Can someone clarify

Answer 1

A blockchain is a collection of nodes that exchange information with each other asynchronously. As a result it's possible for different transactions (with stream items inside) to arrive at different nodes in different orders. So you need to choose what's more important when retrieving – to get consistent ordering from the particular node you're talking to over time (then use local ordering), or to get consistent ordering between all the nodes once they have reached consensus (then use global ordering).

Comments

Thanks, that clarifies alot.