Details
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Improvement
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Resolution: Fixed
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Major - P3
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None
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None
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None
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Query Optimization
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Fully Compatible
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QO 2023-09-18
Description
The sharding subsystem ensures that the index backing a shard key (or the prefix of such an index) is non-multikey. This is make it clear which shard owns a particular document. There are some assumptions in the cascades rewrites that rely on this fact.
To avoid accidentally writing a unit test or translating a shard key in correctly, we should assert that the shard key provided to the optimizer metadata is non-multikey.