Replicated Logs

Divergent Follower

A divergent follower has a conflicting term after the matching prefix.

highlighted = computed this step

A divergent follower

A divergent follower has a conflicting term after the matching prefix. That suffix cannot be treated as leader-consistent. Note: divergent cells are marked in the render.

divergent follower\text{divergent follower}

Conflict mark

The divergent follower matchIndex is 1, and the compiled cluster marks 1 divergent follower. Note: the conflict is term-based.

matchIndex=1,divergent followers=1\text{matchIndex}=1,\quad \text{divergent followers}=1

a simplified leader-based log replication; quorum commit + log repair are exact on these tiny clusters; full Raft safety, leader election (next book), and network partitions/timing are beyond these traces - no product claims.

Divergent follower - quorum 2; committedIndex 2; divergent: F2nodeidx 1idx 2idx 3Lt1:at2:bt2:cF1t1:at2:bF1 repairt1:at2:bt2:cF2t1:at1:xF2 repairt1:at2:bt2:c

Summary

Divergence starts where the follower no longer matches the leader's term. Note: this is simplified leader-based replication; full Raft safety and leader election are the next book, while partitions and timing are beyond these traces.

term conflict\text{term conflict}