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kll_sketch_get_n_bigint function

Applies to: check marked yes Databricks Runtime 18.0 and later

Returns the number of items that have been added to an integer KLL sketch.

Syntax​

kll_sketch_get_n_bigint ( sketch )

Arguments​

  • sketch: A BINARY expression containing a serialized integer KLL sketch.

Returns​

A BIGINT representing the total count of items in the sketch.

Notes​

  • Returns the exact count of items added, not an estimate.
  • Returns 0 for an empty sketch.

Examples​

SQL
> 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]