Chainlink VRF (Verifiable Random Function)

The process of generating a verifiable random number using Chainlink VRF involves two primary steps. In the initial step, the requesting smart contract (Contract) invokes the requestRandomWords() function, which sends a request for random number generation to the Chainlink oracle network. Once the randomness is computed off-chain, Chainlink responds by executing the callback function Contract.fulfillRandomWords(), supplying the generated random words. In that moment, logical exeution initiated with request can continue.

During this process, various events are emitted by the Chainlink VRF Coordinator, including the requestId, which serves as a unique identifier. This requestId allows the linking of the request and the subsequent fulfillment.

What is the logic behind Dune query below

Let's call the first step as request and second step (fullfilment) we can call response. First we need to match request and response logs that have the same requestId. It is indexed log in response, but not in request, so we need to extract it from request.data

FROM ethereum.logs as request 
JOIN ethereum.logs as response 
ON substr(request.data,1,32) = response.topic1

Then we need to find specific request logs that correspond to signature RandomWordsRequested(bytes32,uint256,uint256,uint64,uint16,uint32,uint32,address).

Finally, we can return URLs of tenderly and etherscan explorer to actually see the transaction details.

SELECT 
request.block_number as request_bn,
response.block_number as response_bn,
concat('https://dashboard.tenderly.co/tx/mainnet/0x', to_hex(request.tx_hash)) as request_tenderly, 
concat('https://dashboard.tenderly.co/tx/mainnet/0x', to_hex(response.tx_hash)) as response_tenderly,
concat('https://etherscan.io/tx/0x', to_hex(request.tx_hash)) as request_etherscan,
concat('https://etherscan.io/tx/0x', to_hex(response.tx_hash)) as response_etherscan
FROM ethereum.logs as request 
JOIN ethereum.logs as response 
ON substr(request.data,1,32) = response.topic1
WHERE 
request.block_time > now() - interval '10' day and
response.block_time > now() - interval '10' day and
request.topic0 = keccak(to_utf8('RandomWordsRequested(bytes32,uint256,uint256,uint64,uint16,uint32,uint32,address)'))
ORDER BY request.block_time DESC

Connected Dune analytics dashboard is on the following link. https://dune.com/stuparm/chainlink-vrf-transactions

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