Function isStored

Check if generated column is stored (persisted) or virtual.

When options.stored is explicitly set, that value is used as-is. When it is left unspecified, the default depends on the target dialect:

• PostgreSQL (before v18) only supports STORED generated columns — VIRTUAL is not a valid option, so it defaults to true (stored).
• MySQL/MariaDB support both VIRTUAL and STORED, and default to VIRTUAL (the lighter-weight option), so this defaults to false.
• Other dialects (sqlite, mssql, oracle) also default to false (virtual/computed, not persisted), matching their typical defaults.