`power(decimal, integer)` overflow for moderate exponents

[neilconway]

Describe the bug

power(decimal, integer) computes base ^ exp on the unscaled integer representation and then normalizes, which leads to overflows before normalization for reasonably sized inputs.

To Reproduce

SELECT power(2.5::decimal(20, 4), 10);
-- Arrow error: Arithmetic overflow: Cannot raise base 25000 to exp 10

Expected behavior

DuckDB:

memory D SELECT power(2.5::decimal(20, 4), 10);
┌────────────────────────────────────────┐
│ power(CAST(2.5 AS DECIMAL(20, 4)), 10) │
│                 double                 │
├────────────────────────────────────────┤
│                        9536.7431640625 │
└────────────────────────────────────────┘

Postgres returns the same.

Additional context

No response

[neilconway]

take