Live Resharding Without Regret: Lessons from Building Valkey's Atomic Slot Migration

QCon San Francisco 2026

Session Distributed Systems

Live Resharding Without Regret: Lessons from Building Valkey's Atomic Slot Migration

Monday Nov 16 / 10:35AM PST, Ballroom BC at Hyatt Regency, San Francisco

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$2,955, Conference (3 days)
Current pricing ends October 13th

Abstract

Sharding is easy. Resharding under heavy load is notoriously difficult. How do you move gigabytes of state across live database nodes without dropping keys, blocking the main event loop, or breaking client abstractions?

Using Valkey and Redis as case studies, we will survey different resharding architectures and dive deep into Valkey's new Atomic Slot Migration. We'll walk through the practical tradeoffs of these approaches, covering client redirections (MOVED/ASK), fork-based slot snapshotting, and rollback staging. Along the way, we'll shine a light on the rough edge cases that actually matter in production.

Topics

Distributed Systems Architecture Database Engineering Open Source Reliability
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$2,955, Conference (3 days). Current pricing ends October 13th. All pass options.

76% senior dev or higher
1:11 speaker ratio
60+ practitioners

QCon San Francisco 2026 is a three day conference for senior software engineers, architects and team leads. An international program committee of working engineers selects every session. Patterns and practices, not products and pitches.

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Monday 16 November

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Current pricing ends October 13th
$2,955, Conference (3 days)

Register