Categories:: Data metric functions

APPROX_QUANTILE_99 (system data metric function)¶

Returns the approximate 99th percentile (P99) value for the specified column in a table. Use this function to detect outliers and monitor tail behavior. Commonly used for SLO monitoring on latency metrics.

This topic provides the syntax for calling the function directly. To learn how to associate the function with a table or view so it runs at regular intervals, see Associate a DMF.

Syntax¶

SNOWFLAKE.CORE.APPROX_QUANTILE_99(<query>)

Arguments¶

query: Specifies a SQL query that projects a single column.

Allowed data types¶

The column projected by the query must have one of the following data types:

FLOAT
NUMBER

Returns¶

The function returns a FLOAT value.

Example¶

Measure the approximate P99 of the latency_ms column:

SELECT SNOWFLAKE.CORE.APPROX_QUANTILE_99(
  SELECT
    latency_ms
  FROM metrics.tables.requests
);