Concepts

Minimum fees

A minimum fee represents the minimum amount of sdk.Coins that must be present inside the transaction fees when broadcasting a message of a given type. Setting a minimum fee of 100token for a message types means that users will need to pay at least 100token for each message of that type they broadcast. Trying to broadcast a transaction with multiple message of such types will require the user to pay n * min_fee fees or above.

For each message type, there can only be a single minimum fee amount that needs to be paid at any given time.

A single minimum fee amount can be made of multiple coin amounts, so that if a minimum fee amount is set to 100tokenA,50tokenB this means that for each message of such type the user will have to pay at least 100 tokenA and 50 tokenB to make sure the transaction is valid.

If a transaction contains multiple messages of different kinds, each one having a custom minimum fee amount, the overall transaction fee must be greater or equal to the sum of all the minimum fee amounts. So that if a transaction contains one message which minimum fee amount is 100tokenA and other one which minimum fee is 100tokenB, the overall transaction fee will have to be 100tokenA + 100tokenB or greater.

Failing to provide a transaction fee amount that is not enough to satisfy all the minimum fee requirements will lead to an invalid transaction.