OP Chains - Indexing Updates for Ecotone (EIP4844)

[MSilb7]

OP Chains - Indexing Updates for Ecotone (EIP4844)

This doc outlines how OP Analytics is thinking about indexing updates for Ecotone/EIP4844. Comment in this discussion for any questions / clarifications.

The Ecotone upgrade for OP Chains, which adds support for blobs in EIP4844, is scheduled for March 14th at 00:00:01 UTC.

For fee breakdowns & chain economics calculations, this requires:

• Reading additional fields from the L2 Transaction Receipt (so we can break down by fee contributor).
• Storing historical blobs (or at least aggregate blob metrics).

Calculating transaction fees on L2

The l1Fee abstraction remains unchanged, so the following formula still works in Ecotone (no changes required):

transactionFee = l1Fee + gasUsed * gasPrice

L2 Transaction Receipt

For detailed fee breakdowns, Ecotone introduces two new fields in the transaction receipt:
NOTE: THESE FIELDS WILL NOT BE ADDED UNTIL POST-LAUNCH

• l1BlobBaseFee: The Blob Gas Price charged at the time of the transaction.
• l1BlobBaseFeeScalar: The scalar multiple applied to the blob gas cost.
  Note: These two extra fields may not appear yet on testnets

The total formula is as follows (l1GasBaseFee and l1GasBaseFeeScalar were already in the transaction receipt.

transactionFee = 
l1GasUsed * (16*l1BaseFee*l1BaseFeeScalar + l1BlobBaseFee*l1BlobBaseFeeScalar) / 16e6
+
gasUsed * gasPrice

Historical Blobs

Ideally, we keep the same data that is available in blobscan (Sample L1 Transaction | Sample Blob).

• Blobgas Base Fee (aka Blob Gas Price)
• Blob Hashes per L1 Transaction (i.e. in the sample above, we can read the 6 blob hashes that map to the L1 transaction)
• Blob Data: We’ll use this to calculate how many bytes per blob are used (i.e. count how many bytes there are until the blob becomes empty with repeating 00s until the end of the blob)

[MSilb7]

Update: The Transaction receipt fields will not be added until after Ecotone launch