Compatibility Mode And Native Mode

Informix Version 15.0.0 supports larger tables, chunks, and pages. This support is dependent on the enablement of a new infrastructure that makes low-level disk changes. These changes are so fundamental and extensive that reverting them in-place is not practical. In order to satisfy the potential need for reversion following a migration from an older version, Informix 15.0.0 requires explicit enablement of the new infrastructure by the administrator.

Immediately after the successful completion of an in-place migration from an older Informix server version, an Informix 15.0.0 instance is in compatibility mode. While in this mode the legacy infrastructure, referred to as Infrastructure Version 0, is in effect. The purpose of compatibility mode is to allow the testing of applications against the Version 15.0.0 server while still supporting reversion if necessary. The drawback of compatibility mode is that many Version 15.0.0 features are disabled.

Enabling all Version 15.0.0 features requires switching your instance from compatibility mode to native mode. Once an instance is in native mode it cannot be reverted in-place to an older Informix version. Nor can it be returned to compatibility mode without the physical restoration of an archive. In this case no logical restore may be performed, otherwise the recovered instance will be switched to native mode by a record in the logical logs.