hll_sketch_estimate

hll_sketch_estimate介绍

hll_sketch_estimate(expr) - 根据 Datasketches HllSketch 的二进制表示，返回估计的独特值数量。

Examples:

> SELECT hll_sketch_estimate(hll_sketch_agg(col)) FROM VALUES (1), (1), (2), (2), (3) tab(col);
 3

Since: 3.5.0