fix: topology-aware cache keys with shard epoch to prevent collision during rebalance - #6
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Kasuki354 wants to merge 2 commits into
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fix: topology-aware cache keys with shard epoch to prevent collision during rebalance#6Kasuki354 wants to merge 2 commits into
Kasuki354 wants to merge 2 commits into
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Implements the fix for issue rasoolharlym8#1: cache key collision during tenant shuffle-sharding rebalance. Changes: 1. ShardConfig struct with Epoch and RoutingHash for shard versioning 2. ShardStateManager with RWMutex for thread-safe concurrent access 3. GenerateCacheKey: incorporates tenant shard epoch + routing hash 4. ValidateShardConsistency: detects mid-flight shard transitions When a rebalance occurs, the epoch increments, causing all new cache keys to differ from old ones. This prevents merging fragments from different shard configurations. Resolves rasoolharlym8#1
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Summary
Fixes issue #1: Cache key collision and partial results during tenant shuffle-sharding rebalance.
Implementation
ShardConfig struct: Tracks tenant shard assignment with Epoch (version number) and RoutingHash (hash of shard IDs)
ShardStateManager: Thread-safe manager using sync.RWMutex for concurrent read access during query loads and atomic writes during rebalancing
GenerateCacheKey: Incorporates tenant ID, shard epoch, routing hash, and request hash. When a rebalance occurs, the epoch increments, causing all new cache keys to differ from old ones. This prevents merging fragments from different shard configurations.
ValidateShardConsistency: Detects mid-flight shard transitions by comparing the epoch captured at query start with the current epoch. If changed, cache write-back is aborted.
Tests
/claim #1