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# quantilesTimingArrayIf

> Example of using the quantilesTimingArrayIf combinator

<h2 id="description">
  Description
</h2>

The [`Array`](/reference/functions/aggregate-functions/combinators#-array) and [`If`](/reference/functions/aggregate-functions/combinators#-if)
combinator can be applied to the [`quantilesTiming`](/reference/functions/aggregate-functions/quantileTiming)
function to calculate quantiles of timing values in arrays for rows where the condition is true,
using the `quantilesTimingArrayIf` aggregate combinator function.

<h2 id="example-usage">
  Example usage
</h2>

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.

```sql title="Query" theme={null}
CREATE TABLE api_responses(
    endpoint String,
    response_times_ms Array(UInt32),
    success_rate Float32
) ENGINE = MergeTree
ORDER BY ();

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)

```response title="Response" theme={null}
   ┌─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]                                 │
   └──────────┴─────────────────────────────────────────────────────────────────────┘
```

<h2 id="see-also">
  See also
</h2>

* [`quantilesTiming`](/reference/functions/aggregate-functions/quantileTiming)
* [`If combinator`](/reference/functions/aggregate-functions/combinators#-if)