The pg_extended_date_support extension allows support for BC dates/timestamps by default, and infinite dates/timestamps if configured. Without this extension, BC and infinite dates/timestamps will be handled incorrectly or raise an error. This behavior isn't the default because it can hurt performance, and few users need support for BC and infinite dates/timestamps.
To load the extension into the database:
To enable support for infinite dates/timestamps:
DB.convert_infinite_timestamps = 'string' # or 'nil' or 'float'
Related module: Sequel::Postgres::ExtendedDateSupport