Fees
The XDBChain network requires small fees on transactions and minimum balances on accounts in order to prevent people from overwhelming the network and to aid in prioritization.
There are two special values used to calculate fees:
- The base fee (currently 100 nibbs) is used in transaction fees.
- The base reserve (currently 10 XDB) is used in minimum account balances.
Transaction Fee
The fee for a transaction is the number of operations the transaction contains multiplied by the base fee, which is 100 nibbs (0.00001 XDB).
([# of operations] * [base fee])
For example, a transaction that allows trust on an account’s trustline (operation 1) and sends a payment to that account (operation 2) would have a fee of \(2 * [base fee] = 200 nibbs\).
XDBChain deducts the entire fee from the transaction’s source account, regardless of which accounts are involved in each operation or who signed the transaction.
Transaction Limits
Each XDBChain node usually limits the number of transactions that it will propose to the network when a ledger closes. If too many transactions are submitted, nodes propose the transactions with the highest fees for the ledger’s transaction set. Transactions that aren’t included are held for a future ledger, when fewer transactions are waiting.
See transaction life cycle for more information.
Fee Pool
The fee pool is the lot of XDB collected from transaction fees.
XDBChain does not retain these XDBs. They are distributed into the DXDBChain Algorithmic Pool.
Minimum Account Balance
All XDBChain accounts must maintain a minimum balance of XDB. Any transaction that would reduce an account’s balance to less than the minimum will be rejected with an INSUFFICIENT_BALANCE error.
The minimum balance is calculated using the base reserve, which is 10 XDB:
(2 + [# of entries]) * [base reserve]
The minimum balance for a basic account is \(2 * [base reserve]\). Each additional entry costs the base reserve. Entries include:
- Trustlines
- Offers
- Signers
- Data entries
For example, an account with 1 trustline and 2 offers would have a minimum balance of \((2 + 3) * [base reserve] = 50 XDB\).
Fee Changes
The base reserve and base fee can change, but should not do so more than once every several years. For the most part, you can think of them as fixed values. When they are changed, the change works by the same consensus process as any transaction. For details, see versioning.