Replicated Logs

Committed Is Exact

committedIndex is a deterministic function of the replicated logs.

highlighted = computed this step

Committed is exact

committedIndex is not a guess or a performance claim. It is a pure function of the leader log and which nodes match each prefix entry. Note: recompiling the same cluster gives the same facts.

exact commit\text{exact commit}

Deterministic facts

The committedIndex is 2 across 2 followers. Note: follower match facts are recomputed with the same pass.

committedIndex=2,followers=2\text{committedIndex}=2,\quad \text{followers}=2

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.

Committed is exact - 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

Exact replication lessons expose the deterministic core before timing and elections. 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.

exact core\text{exact core}