kll_sketch_get_n_bigint 函数

适用于： Databricks Runtime 18.0 及更高版本

返回已添加到整数 KLL 草图的项数。

Syntax

kll_sketch_get_n_bigint ( sketch )

Arguments

• sketch BINARY：包含序列化整数 KLL 草图的表达式。

退货

一个 BIGINT 表示草图中项的总计数。

注释

• 返回添加的项的确切计数，而不是估计项。
• 空草图返回 0。

例子

> WITH sketch_data AS (
    SELECT kll_sketch_agg_bigint(value) AS sketch
    FROM VALUES (1), (2), (3), (4), (5) AS T(value)
  )
  SELECT kll_sketch_get_n_bigint(sketch) FROM sketch_data
  5

-- Check if sketch has sufficient data for reliable estimates
> WITH sketch_data AS (
    SELECT kll_sketch_agg_bigint(value) AS sketch FROM my_table
  )
  SELECT
    CASE
      WHEN kll_sketch_get_n_bigint(sketch) >= 1000
      THEN kll_sketch_get_quantile_bigint(sketch, 0.95)
      ELSE NULL
    END AS p95_if_sufficient_data
  FROM sketch_data
  [results]

相关函数

• kll_sketch_agg_bigint 聚合函数
• kll_sketch_get_n_float 函数
• kll_sketch_get_n_double 函数