Transaction fees for Dynamic Fee Transactions v2 (type 123) on Celo

[wpoulin]

Hi everyone,

I've been working with transaction data on Celo and noticed that for some transactions of type 123 (Dynamic Fee Transaction v2) the eth_getTransactionByHash response does not include gasPrice or effectiveGasPrice.

I’d like to understand how to accurately compute the transaction fees for these transactions, especially in a way that matches what CeloScan and Blockscout display. Normally, I would calculate transaction fees using the formula:

transaction fee = gasPrice * gasUsed

However, since gasPrice (or even effectiveGasPrice) is missing for these transactions, I’m unsure how to compute the correct fee.

e.g 0x7ca62d85bd8f43c67a757dd76b750a8546b9f9e1a2efe4dfc631fd26e0964a9a

Any clarification or pointers to relevant specs would be appreciated!
Hopefully, this is the right place to ask this sort of question

Thanks in advance

[karlb]

Type 123 txs will return the effectiveGasPrice for all receipts after the L2 migration.

For receipts before the L2 migration, the situation is more complicated, since the L1 relied on executing contracts to get the base fee for a block in the respective fee currency, which is required to calculated the effective gas price. This has two effects for type 123 receipts:

• Normal Celo L1 nodes would only return the effective gas price for a short time until the state was pruned
• Celo L2 nodes generally won't return the effective gas price from before the migration

Blockscout has all the data, so you can see the effective gas price for your tx at https://celo.blockscout.com/tx/0x7ca62d85bd8f43c67a757dd76b750a8546b9f9e1a2efe4dfc631fd26e0964a9a

[wpoulin]

Thanks for the clarification!

I’m indexing CELO transactions, and for older Celo L1 transactions of Type 123 where the state might be pruned, what’s the best way to avoid losing access to the effective gas price? Would running a full archive node help, or is there another recommended approach?

[karlb]

If you have access to an Celo L1 archive node, you can get the effectiveGasPrice for all txs from before the migration. Running an L2 archive node won't help, as it is not able to execute contracts from before the migration.