kll_sketch_get_n_bigint 函數

適用於： Databricks 執行環境 18.0 及以後版本

回傳已加入整數KLL草圖的項目數量。

語法

kll_sketch_get_n_bigint ( sketch )

Arguments

• sketch：包含 BINARY 序列化整數 KLL 草圖的表達式。

退貨

A BIGINT 代表素描中物品的總數量。

註釋

• 回傳新增物品的精確數量，而非估計值。
• 對於空草圖則回傳 0。

範例

> 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]

相關功能

• kll_sketch_agg_bigint 聚合函數
• kll_sketch_get_n_float函式
• kll_sketch_get_n_double函式