Operations Manual
Floating-Point Aggregate Operations with Multi-Threading
Floating-point inaccuracies may produce different results when run in a multi-threaded configurations:
For example, [`stddev` and `corr` may produce non-deterministic results](https://github.com/duckdb/duckdb/issues/13763):  
```sql
CREATE TABLE tbl AS
SELECT 'ABCDEFG'[floor(random() * 7 + 1)::INT] AS s, 3.7 AS x, i AS y
FROM range(1, 1_000_000) r(i);

SELECT s, stddev(x) AS standard_deviation, corr(x, y) AS correlation FROM tbl
GROUP BY s
ORDER BY s;
```  
The expected standard deviations and correlations from this query are 0 for all values of `s`.
However, when executed on multiple threads, the query may return small numbers (` 0 <= z < 10e-16`) due to floating-point inaccuracies.