COUNT DISTINCT 用ビットマップ
Use bitmaps in StarRocks for efficient COUNT(DISTINCT) calculations with the BITMAP type and bitmap functions, reducing storage space and improving speed.
おおよその重複排除にHLLを使用する
Use HyperLogLog (HLL) in StarRocks for approximate COUNT(DISTINCT) with ~1-10% error rate, significantly reducing memory usage for large-scale data.