Is importaddress idempotent?

Question

Each time when "importaddress" is executed, the transaction returns a new id from the output.

What is this id referring to and how what can it be used for?

What are the changes to the state of the blockchain when you run importaddress for an already imported address?

Are the implications to running importaddress multiple times or a call to importaddress is made a prior to every transaction?

Answer 1

Yes, it is idempotent. This ID you see belongs to the JSON-RPC request, it is not anything to do with the blockchain or node state. Importing an address has zero effect on the blockchain, it just adds the address to the node's wallet, without a corresponding private key, so the node tracks the activity of that address.