Boolean flag columns bypass skewed statistics in filter selectivity

When range predicates on columns with skewed statistics cause optimizer to misestimate cardinality, transforming the range check into a pre-computed boolean flag column allows the optimizer to use accurate statistics on the boolean column instead of the skewed numeric column.

For columns with known statistical skew causing query plan issues, add computed boolean flag columns at data ingestion time (e.g., CASE WHEN duration BETWEEN 0 AND 1800000 THEN 1 ELSE 0 END AS is_valid_duration). Filter on the flag column (is_valid_duration = 1) instead of the raw column. This gives the optimizer accurate cardinality estimates for the boolean column's statistics.