hyperledger fabric v1.0 using query on methods that change ledger - hyperledger

Question

While going over v1.0 examples, I ran into a confusion.
As far as I understand, query does not change the ledger as it is executed locally (e.g. no ordering, committing, endorsing involved).
But that is from the caller's point of view. Within chaincode, it just executes whatever the client calls given all of CAs and info are valid.
So for example, if I call
peer chaincode query -C mychannel -n chaincode -c '{"Args":["query", "a"]}'
this would be ok. It just queries a.
But if I call
peer chaincode query -C mychannel -n chaincode -c '{"Args":["**invoke**", "a"]}'
What would be the behavior given that invoke involves writing on the ledger?
Also on the other hand, if I call invoke on query method
(e.g. peer chaincode invoke ~~~ {"Args":["query", "a"]})
What would be the behavior?
As far as I understand, actual chaincode cannot distinguish whether it is query or invoke. It just executes the chaincode method.
Am I far off?

Answer 1

Indeed this is a bit confusing, especially taking into account the thing not very obvious when you using the cli tool. Here is the thing, when you are using peer cli command with invoke the flow works as following:
You send transaction proposal to the endorsing peer
Endorsing peers executes transaction simulations and signs the results
Client receives the results and send them out to the ordering service
Ordering service cut the block
Block delivered to the peers
Peers validates transactions
Eventually block appended to the blockchain
Now here is the difference, when you running peer cli with query parameters key it will do only:
You send transaction proposal to the endorsing peer
Endorsing peers executes transaction simulations and signs the results
Therefore, since results is not sent to ordering service there is no effect on the final peer state, since even if you chaincode has made any changes it won't be committed.