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quantilesTimingArrayIf

Description​

The Array and If combinator can be applied to the quantilesTiming function to calculate quantiles of timing values in arrays for rows where the condition is true, using the quantilesTimingArrayIf aggregate combinator function.

Example usage​

In this example, we'll create a table that stores API response times for different endpoints, and we'll use quantilesTimingArrayIf to calculate response time quantiles for successful requests.

CREATE TABLE api_responses(
    endpoint String,
    response_times_ms Array(UInt32),
    success_rate Float32
) ENGINE = Log;

INSERT INTO api_responses VALUES
    ('orders', [82, 94, 98, 87, 103, 92, 89, 105], 0.98),
    ('products', [45, 52, 48, 51, 49, 53, 47, 50], 0.95),
    ('users', [120, 125, 118, 122, 121, 119, 123, 124], 0.92);

SELECT
    endpoint,
    quantilesTimingArrayIf(0, 0.25, 0.5, 0.75, 0.95, 0.99, 1.0)(response_times_ms, success_rate >= 0.95) as response_time_quantiles
FROM api_responses
GROUP BY endpoint;

The quantilesTimingArrayIf function will calculate quantiles only for endpoints with a success rate above 95%. The returned array contains the following quantiles in order:

  • 0 (minimum)
  • 0.25 (first quartile)
  • 0.5 (median)
  • 0.75 (third quartile)
  • 0.95 (95th percentile)
  • 0.99 (99th percentile)
  • 1.0 (maximum)
   ┌─endpoint─┬─response_time_quantiles─────────────────────────────────────────────┐
1. │ orders   │ [82, 87, 92, 98, 103, 104, 105]                                     │
2. │ products │ [45, 47, 49, 51, 52, 52, 53]                                        │
3. │ users    │ [nan, nan, nan, nan, nan, nan, nan]                                 │
   └──────────┴─────────────────────────────────────────────────────────────────────┘

See also​