# AUTO_RANDOM generated-value range

Use this topic only when the customer's compatibility goal depends on the
numeric range of every ID, not merely the values generated automatically by
TiDB.

- In `AUTO_RANDOM(S, R)`, `R` limits the range of values that TiDB generates
  automatically.
- `R` does not cap values supplied by an explicit insert or values already
  present in migrated data.
- If the compatibility goal applies to every downstream ID, tell the customer
  to check existing or migrated values and every explicit-insert path
  separately against that limit.
- A generic warning to avoid explicit inserts because of allocation or
  collision risk is not a substitute for this range boundary.

Confirm version-specific syntax and generated-value behavior from applicable
official documentation. Do not extend this conclusion to an undocumented
version or insertion path.