When NOT to use

Non-finite or special float values

NaN, Infinity, -Infinity are deliberately unsupported — construction throws DecimalError (NON_FINITE). If your domain needs them (statistics, sensor streams, scientific computing), use number or a domain-specific type.

Transcendental / irrational math

There is no sqrt, log, sin, exp — a Decimal is always a finite rational base-10 number. Irrational results would require an infinite expansion. Use number (or Math.*) for geometry, statistics, physics.

Hot-loop performance on integers

bigint arithmetic is fast but still allocates per operation. For pure integer counters, indexes, pagination, bitmasks — number (or bigint directly) is cheaper. Decimal pays for exactness you may not need.

Ratios that must stay rational forever

div truncates at a finite scale (PG-faithful default or explicit). If you need to keep 1/3 as a symbolic rational for later exact arithmetic, you need a rational-number library (numerator/denominator pairs) — isPeriodic only tells you a truncation happened.

Rule of thumb

• Values that must match numeric columns or money semantics → Decimal
• Counts, indexes, flags → number/bigint
• Scientific/statistical math → number + domain library