pub fn build_histogram(sorted_values: &[String]) -> Vec<String>Expand description
Build an equi-depth histogram over a (sorted) sample of textual column values. Returns the 101 boundary strings, or an empty vec when the input has no non-NULL values.
The caller sorts the sample via the column’s natural ordering
(TEXT lexicographic, INT decimal, etc.) and hands us the
already-stringified values — we don’t try to reason about types
here. Equi-depth means each consecutive pair of bounds spans
approximately sample.len() / NUM_BUCKETS values; selectivity
estimation in v6.2.2 walks bounds directly.