SAMPLE_POISSON()

All functions > BUSINESS > SAMPLE_POISSON()

Returns an integer drawn from a Poisson distribution with the given rate, based on the given hashing key.

Signatures

Returns: Deterministic non-negative integer from Poisson distribution

SAMPLE_POISSON(hashing_key: VARCHAR, rate: DOUBLE) → BIGINT

Notes

• Deterministic - same key always produces same value
• Uses inverse CDF method with Horner-form polynomial evaluation
• Output is a non-negative integer (count of events)
• Accurate for rate up to ~20 (covers 99.999%+ of probability mass)
• For rate > 20, output is capped at 40 (tail truncation)
• Models event counts per interval (arrivals, defects, requests)
• Common for demand forecasting, queue depth simulation
• Rate must be strictly positive

Examples

SELECT
    f1 := SAMPLE_POISSON('k', 5E0) -- Poisson draw with rate 5 for a fixed key
;