proto: add NDV rate to analyze request#410
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May 14, 2026
…tches Add row-level Bernoulli sampling to the table scan executor so ANALYZE can build distinct-value sketches from a subset of rows. The sampling rate is taken from the new AnalyzeColumnsReq.ndv_rate field (pingcap/tipb#410); when it is unset, the scanner keeps every row. Build an F1 (singleton) sketch alongside the FM sketch and report it with sketch_sample_count in the row collector. Null counts and total sizes are rescaled from the sampled rows back to the full row count. Signed-off-by: 0xPoe <techregister@pm.me>
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Ref pingcap/tidb#67449
What changed
AnalyzeColumnsReq.ndv_ratefor NDV sampling rate.Tests
make check