Replaying Past Transactions

Basics

You can replay past transactions locally using the aptos move replay command. The command is fairly straightforward but it requires you to specify two pieces of required information:

--network
- This is the network you want to replay on
- Possible values: mainnet, testnet, devnet or <URL TO CUSTOM REST ENDPOINT>
--txn-id
- This is the id of the transaction you want to replay
- This is also sometimes being referred to as version on explorers
- Specifically it is NOT the hexadecimal transaction hash

Let’s use mainnet transaction 581400718 (a simple coin transfer transaction) as an example.

Terminal

aptos move replay --network mainnet --txn-id 581400718

Output

Got 1/1 txns from RestApi.
Replaying transaction...
{
  "Result": {
    "transaction_hash": "0x1ba73d03a0442a845735a17c7be46f3b51e2acb0e5cf68749305c5a17539ac63",
    "gas_used": 7,
    "gas_unit_price": 100,
    "sender": "c94e16736910cc160347d01de345407fe2d350fce5635ac1150319b0fbf5630e",
    "sequence_number": 14637,
    "success": true,
    "version": 581400718,
    "vm_status": "status EXECUTED of type Execution"
  }
}

Alternatively, if you want to simulate a new transaction, check out Local Simulation, Benchmarking and Gas Profiling.

Alternate Modes

Similar to local simulations, the replay command can be enhanced with one of the following options:

--benchmark: Benchmark the transaction and report the running time(s).
--profile-gas Profile the transaction for detailed gas usage.

Benchmarking

Terminal

aptos move replay --network mainnet --txn-id 581400718 --benchmark

Output

Got 1/1 txns from RestApi.
Benchmarking transaction...
Running time (cold code cache): 914.821µs
Running time (warm code cache): 820.189µs
{
  "Result": {
    "transaction_hash": "0x1ba73d03a0442a845735a17c7be46f3b51e2acb0e5cf68749305c5a17539ac63",
    "gas_used": 7,
    "gas_unit_price": 100,
    "sender": "c94e16736910cc160347d01de345407fe2d350fce5635ac1150319b0fbf5630e",
    "sequence_number": 14637,
    "success": true,
    "version": 581400718,
    "vm_status": "status EXECUTED of type Execution"
  }
}

It’s worth noting that these running times serve only as informational references, as they are contingent upon the specifications of your local machine and may be influenced by noise or other random factors.

If you are aiming to optimize your contract, you should base your decisions on the gas profiling results.

ℹ️

To minimize measurement errors, the benchmark harness executes the same transaction multiple times. For this reason, it may take a while for the benchmark task to complete.

Gas Profiling

The Aptos Gas Profiler is a powerful tool that can help you understand the gas usage of Aptos transactions. Once activated, it will simulate transactions using an instrumented VM, and generate a web-based report.

The gas profiler can also double as a debugger since the report also includes a full execution trace.

Terminal

aptos move replay --network mainnet --txn-id 581400718 --profile-gas

Output

Got 1/1 txns from RestApi.
Profiling transaction...
Gas report saved to gas-profiling/txn-1ba73d03-0x1-aptos_account-transfer.
{
  "Result": {
    "transaction_hash": "0x1ba73d03a0442a845735a17c7be46f3b51e2acb0e5cf68749305c5a17539ac63",
    "gas_used": 7,
    "gas_unit_price": 100,
    "sender": "c94e16736910cc160347d01de345407fe2d350fce5635ac1150319b0fbf5630e",
    "sequence_number": 14637,
    "success": true,
    "version": 581400718,
    "vm_status": "status EXECUTED of type Execution"
  }
}

You can then find the generated gas report in the directory gas-profiling:

- - index.html

To understand the gas report, please refer to this section of the local simulation tutorial.

Use Hardware Ledger Running a Local Network