Index ERC-20 transfers

This tutorial builds an event table of USDC transfers on Ethereum mainnet, recording the sender, recipient, amount, and transaction hash.

chain.event.eth → Filter USDC Transfer events → Extract transfer fields → Transfer event table

1. Create a transfer event table

In Tables, create a table named usdc_transfers, select Block Event, and choose Ethereum. The resulting table ID is demo.usdc_transfers.eth.

Create an Ethereum Block Event Table in Tables

Add the following fields in Schema, keeping the system fields and other defaults:

Field	Type	Content
`tx_id`	`TXID`	Transaction hash
`from_address`	`ADDRESS`	Sender address
`to_address`	`ADDRESS`	Recipient address
`amount`	`UINT256`	Raw integer transfer amount

Transfer table schema with default configuration retained

2. Run the Pipeline

Configure the Pipeline

In Notebooks, create backfill_usdc_transfers and enter the following code. Replace SPACE with your Space ID:

from blockdb import Column, filter
from blockx import Pipeline, Trigger, SOURCE_ROW

SPACE = 'demo'


def parse_usdc_transfer(event):
    sender, recipient, amount = event['params']
    return {
        'id': event['id'],
        'tx_id': event['tx_id'],
        'from_address': sender,
        'to_address': recipient,
        'amount': amount,
    }


pipeline = Pipeline(
    triggers=[
        Trigger(
            table='chain.event.eth',
            func=parse_usdc_transfer,
            params=[SOURCE_ROW],
            operator=filter(
                (Column('contract_id') == '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48')
                & (Column('name') == 'Transfer')
            ),
        ),
    ],
    target_table=f'{SPACE}.usdc_transfers.eth',
)

pipeline.backfill(block_start=25939925, block_end=25939934)

The code processes data as follows:

Trigger selects USDC Transfer events.
SOURCE_ROW passes each selected event to the function.
parse_usdc_transfer extracts the sender, recipient, and amount from decoded params.
The Pipeline writes returned records to the transfer table specified by target_table.

This example defines the function directly in the Notebook. You can also set func to an existing Function ID.

Run the backfill

Save and click Run. View progress and results in Output. backfill() processes the specified 10 blocks, including both boundary heights, then exits.

Backfill call and completed output in backfill_usdc_transfers

3. View transfer data

Return to usdc_transfers.eth and check the processed blocks in Overview. This run backfills only a limited range; earlier history is still missing.

Transfer table progress with default settings and the event subtable entry

Open event under Subtables to view transfer records.

Actual USDC transfer records in the event subtable

Each record uses the source event’s id. The Pipeline fills in block fields automatically. amount retains the raw integer value. Divide it by 10^6 to get the USDC amount.

Optional: keep the table updated

Create a Notebook named update_usdc_transfers, copy the code above, and replace the final pipeline.backfill(...) line with the following call. Save and run:

pipeline.update()

By default, update() fills history from the earliest unfinished block, then keeps updating after reaching the latest block. For a large backlog, you can also run backfill() in another Notebook at the same time to speed up historical processing.

Continuous update call and historical processing logs in update_usdc_transfers

Select Switch to Background to run in the background. Cancel the instance in the account’s Instances page to stop it. Data already written is retained.

Overview

Quickstart

Guides

Reference

Index ERC-20 transfers

1. Create a transfer event table

2. Run the Pipeline

Configure the Pipeline

Run the backfill

3. View transfer data

Optional: keep the table updated

​1. Create a transfer event table

​2. Run the Pipeline

​Configure the Pipeline

​Run the backfill

​3. View transfer data

​Optional: keep the table updated

1. Create a transfer event table

2. Run the Pipeline

Configure the Pipeline

Run the backfill

3. View transfer data

Optional: keep the table updated