fix(encoding): improve dict sampling for sorted strings#7159
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June 8, 2026 17:18
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Summary
Fix dictionary encoding selection for sorted low-cardinality string data by replacing stride-based near-unique sampling with deterministic block sampling.
The previous stride sampler could sample one value from each sorted run and classify low-cardinality data as near-unique, causing Lance to skip dictionary encoding. The new sampling path also projects sampled cardinality against the dictionary budget so sorted high-cardinality short runs do not fall into an expensive full-page dictionary probe.
Closes #6941.