E-Business Suite R12.1.1 - Which database version?

Fooling around with E-Business Suite R12.1.1 installation this week led to some confusion about which database version comes with the distribution.

The first surprise came when we started Rapid Install and unfolded the components to be installed, as outlined in the welcome screen:

Huh? 9.2.0.5??? I thought 11.1.0.7 was to be installed with R12? 9.2.0.5 isn't even certified.

After we entered all the information, the installation was kicked off, and we saw the following information on our screen:

Still, not quite the version that we were expecting, but coming close, at least.
After the installation was finished, we were - again - mislead, as you can see in this and the following screenshot:

Luckily, checking the database version from within E-Business Suite (Help - About), finally told us the truth, and nothing but the truth:

So it is true! Oracle E-Business Suite Release 12.1.1 comes with 11.1.0.7 database!

Upgrading 11.5.9 base to R12.1.1: Do we need CU2 or not?

We have recently started the process of upgrading one of our customers environments to R12.1.1. The current version of the E-Business Suite is 11.5.9 base.
First thing we did was to investigate the Oracle Applications Upgrade Guide: Release 11i to Release 12.1.1.
This document states (Chapter 1, Supported Upgrade Paths, on page 1-1) that it is possible to upgrade from 11.5.9 base, directly to R12.1.1.
However, the text on page 2-29 (Prepare for the Upgrade, Step 4: Migrate or upgrade your database to at least Oracle 10g Release 2) can be a bit misleading. The text states the following:

Oracle Applications Release 11.5.9 (with CU2 applied) and Release 11.5.10 (with CU2applied) are certified for use with Oracle 10g Release 2, while 11.5.10 (with CU2) iscertified for use with Oracle 11g Release 1. If you have not already done so, you canupgrade your production database to at least 10g now, before the upgrade downtime.Follow the instructions in Database Preparation Guidelines for an Oracle E-Business SuiteRelease 12.1.1 Upgrade (Doc ID: 761570.1).

The misleading part (in a way) is the first line. The conclusion one can draw here is that is is necessary to first apply CU2 to 11.5.9 base before upgrading the database to 10gR2. We almost did, anyway. Further investigation in the provided note (761570.1) showed us that we need to apply the Interoperability Notes for Oracle 10gR2 database with 11i Applications (Note 362203.1), but skip the following sections:

• Verify software versions
• run adgrants.sql
• implement and run Autoconfig
• re-create grants and synonyms
• apply Oracle Receivables patch
• restart Applications Server processes

The first mentioned section (Verify software versions) is the section that holds the instruction to apply CU2 to 11.5.9.

In short, if

• your E-Business Suite is at level 11.5.9 base or CU1 and
• your E-Business Suite database is 9.2.0.x,

in the process of upgrading to R12.1.1, there is no need to apply CU2 to 11.5.9 before upgrading your database to 10gR2.

PS. It is not possible to upgrade your 11.5.9/9.2.0.x database to 11gR1. You will not use the 11gR1 ORACLE_HOME, which is delivered with your R12.1.1 techstack installation during the upgrade. If you want to upgrade your database to 11gR1, you can do so after the upgrade to R12.1.1 has completed.