Match OpenSearch shard routing in pull-ingestion IndexRouter#7013
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The pull-ingestion IndexRouter computed the Murmur3 hash over UTF-8 bytes, but OpenSearch's Murmur3HashFunction.hash(String) hashes UTF-16 little-endian bytes, so documents could be routed to a different partition than the shard OpenSearch places them on. The shard calculation also used floorMod(hash, numberOfShards) instead of OpenSearch's floorMod(hash, routingNumShards) / routingFactor, diverging whenever number_of_routing_shards differs from number_of_shards. Hash the UTF-16 little-endian bytes, source number_of_routing_shards from the index settings (falling back to number_of_shards), and scale by routingFactor so partition assignment matches OpenSearch's OperationRouting.generateShardId. Adds a cross-check against OpenSearch's authoritative Murmur3HashFunction known values and known-answer shard tests. Resolves opensearch-project#6993 Signed-off-by: Srikanth Padakanti <srikanth_padakanti@apple.com>
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dinujoh,
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dlvenable,
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san81,
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July 20, 2026 16:34
…index settings Signed-off-by: Srikanth Padakanti <srikanth_padakanti@apple.com>
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Hello @kkondaka @dlvenable Please review this. |
dlvenable
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Jul 21, 2026
…ngFactor, unify parsing, strengthen test Signed-off-by: Srikanth Padakanti <srikanth_padakanti@apple.com>
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Description
The pull-ingestion IndexRouter computed the Murmur3 hash over UTF-8 bytes, but OpenSearch's Murmur3HashFunction.hash(String) hashes UTF-16 little-endian bytes, so documents could be routed to a different partition than the shard OpenSearch places them on. The shard calculation also used floorMod(hash, numberOfShards) instead of OpenSearch's floorMod(hash, routingNumShards) / routingFactor, diverging whenever number_of_routing_shards differs from number_of_shards.
Hash the UTF-16 little-endian bytes, source number_of_routing_shards from the index settings (falling back to number_of_shards), and scale by routingFactor so partition assignment matches OpenSearch's OperationRouting.generateShardId. Adds a cross-check against OpenSearch's authoritative Murmur3HashFunction known values and known-answer shard tests.
Issues Resolved
Resolves #6993
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