What's the difference between `answeredInRound` and `roundId` in a chainlink price feed?

Question

In a chainlink price feed, we can get data by calling:

function latestRoundData() external view
    returns (
        uint80 roundId,
        int256 answer,
        uint256 startedAt,
        uint256 updatedAt,
        uint80 answeredInRound
    )

With the following return values:

• roundId: The round ID
• answer: The answer for this round
• startedAt: Timestamp of when the round started
• updatedAt: Timestamp of when the round was updated
• answeredInRound: The round ID in which the answer was computed

Would roundId ever be different from answeredInRound? What is the difference between the two?

Answer 1

roundId is the "round" the answer was created in. Every time a Chainlink network updates a price feed, they add 1 to the round.

answeredInRound is a legacy variable from when the Chainlink price feeds was on the Flux Aggregator model instead of OCR (Off-Chain Reporting) and it was possible for a price to be updated slowly and leek into the next "round". This is now no longer the case.