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We add a new quorum state Prospective for servers which are sending Pre-Vote requests as well as new state transitions. The original (left) and new states (right) are below for comparison. | Column |
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| * Unattached|Resigned transitions to:
* Unattached: After learning of a new election with a higher epoch
* Voted: After granting a vote to a candidate
* Candidate: After expiration of the election timeout
* Follower: After discovering a leader with an equal or larger epoch
*
* Voted transitions to:
* Unattached: After learning of a new election with a higher epoch
* Candidate: After expiration of the election timeout
*
* Candidate transitions to:
* Unattached: After learning of a new election with a higher epoch
* Candidate: After expiration of the election timeout
* Leader: After receiving a majority of votes
*
* Leader transitions to:
* Unattached: After learning of a new election with a higher epoch
* Resigned: When shutting down gracefully
*
* Follower transitions to:
* Unattached: After learning of a new election with a higher epoch
* Candidate: After expiration of the fetch timeout
* Follower: After discovering a leader with a larger epoch
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| Column |
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| * Unattached|Resigned transitions to:
* Unattached: After learning of a candidate with a higher epoch (clarifying language)
* Voted: After granting a standard vote to a candidate (clarifying language)
* Prospective: After expiration of the election timeout
* Follower: After discovering a leader with an equal or larger epoch
*
* Voted transitions to:
* Unattached: After learning of a candidate with a higher epoch
* Prospective: After expiration of the election timeout
* Follower: After discovering a leader with an equal or larger epoch (missed in original docs) *
* Prospective transitions to:
* Unattached: After learning of a candidate with a higher epoch
* Prospective: After expiration of the election timeout
* Candidate: After receiving a majority of pre-votes
* Follower: After discovering a leader with an equal or larger epoch
*
* Candidate transitions to:
* Unattached: After learning of a candidate with a higher epoch
* Prospective: After expiration of the election timeout
* Leader: After receiving a majority of standard votes
* Follower: After discovering a leader with an equal or larger epoch (missed in original docs)
*
* Leader transitions to:
* Unattached: After learning of a candidate with a higher epoch
*
* Follower transitions to:
* Unattached: After learning of a candidate with a higher epoch
* Prospective: After expiration of the electionfetch timeout
* Follower: After discovering a leader with a larger epoch |
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A candidate follower will now transition to Prospective when its fetch timeout expires. The Prospective server will send a VoteRequest with the PreVote field set to true and CandidateEpoch set ReplicaEpoch set to its [epoch + 1] when its election timeout expirescurrent, unbumped epoch. If [majority - 1] of VoteResponse grant the vote, the candidate server will transition to Candidate and will then bump its epoch up and send a VoteRequest with PreVote set to false (which is our standard vote that will cause state changes for servers receiving the requestthe original behavior).
When servers receive VoteRequests with the PreVote field set to true, they will respond with VoteGranted set to
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