read repair pattern
On reads, when replicas disagree, fix the inconsistency right then by writing the newer value back to lagging replicas. Quietly converges the system without a separate sync process — the act of reading does the healing.
On reads, when replicas disagree, fix the inconsistency right then by writing the newer value back to lagging replicas. Quietly converges the system without a separate sync process — the act of reading does the healing.
symptoms
- replica divergence after partial failures
- stale reads from some replicas
causes
- asynchronous replication with occasional dropped updates
- node downtime + missed writes
fixes
- read-repair on every read (strong eventual consistency)
- anti-entropy sweep for cold data
- version vectors to determine winner
you might say
- read-repair on the fly
- repair while serving