Clarify Oracle System Database Requirements

Oracle System Database Requirements need clarification on the following:
1. Are there any CPU or Memory requirements? 

1A. This will be addressed by THREESCALE-8336 .

2. Looks like it requires the `SYSTEM` user: solution . Does it always need the SYSTEM user? Or, just during install/upgrade? In the downloaded /amp/system-oracle/README.d in the 2.11.1-GA directory it is noted ```It will create the user and grant the appropriate roles and rights to the user connecting to the database.```

2A. SYSTEM user is required during install and upgrade.  The system-database-secret , "Note" section has the following text related to this question.
[Darren] Much of this content has been redone/reviewed/approved as of 2.14. I don't think this is relevant in the current version.
 

• The Oracle system user executes commands with system privileges. Some are detailed in this GitHub repository. The latest can be executed in the Oracle Database initializer when the tables are initialized in the database. There may be other commands executed not listed in these links
• The system user is also required for upgrades when there are any schema migrations to run, so other commands not included in the previous links may be executed.

The second point is clear. The first item above is not clear. First, the description is from 3scale implementation perspective ( privileges required , operations executed ) . It does not mention that all of these are performed at "installation time". This has to be inferred which is only by developers or people knowledgeable about the code not by users ( customers) who are reading the docs. This needs to be clarified.

The regular user must be created . Addressed by THREESCALE-8552 and  THREESCALE-8738

3. 3scale 2.12 install instructions , are referencing 2.11-download-software . Is this correct ? 

• • 2.11 directory name - 3scale-amp-openshift-templates-3scale-2.11.1-GA . There is no 2.12-GA directory as shown below in the same doc section 

    tar -xzf 3scale-amp-openshift-templates-3scale-2.12-GA.tar.gz
    

• • /amp/system-oracle/Dockerfile in the above 2.11.1-GA extracted directory is using a 2.11 image

    FROM registry.redhat.io/3scale-amp2/system-rhel7:3scale2.11

3A. This is a bug and has already been fixed in 2.12 docs by THREESCALE-8512 .
[Darren] Since templates no longer exist, there is a problem with this in 2.13 docs and greater. THREESCALE-8571 will resolve it.

4. docs and downloaded files reference different Oracle client versions. From 3scale docs for Oracle installation from the link Instant Client Downloads for Linux x86-64 (64-bit) , only the latest 19 version 19.16.0.0.0 is available ( for example
instantclient-basic-linux.x64-19.16.0.0.0dbru.zip ) . But the same docs in list item 3, has a table 2.1, "Oracle 19c example packages for 3scale" which shows 19.8.0.0.0 versions ( e.g. instantclient-basic-linux.x64-19.8.0.0.0dbru.zip ) . Can the 19.16.0.0.0.0 version be used ?  3scale supported configurations references Version 19 for Oracle DB.

4A. In code we set the version here and then check for the local assets matching that version here and so if it is not found to match we will download that automatically. Based on that it seems like the documentation currently lists a misleading version and needs to be fixed so that it matches what the code expects to find.
[Darren] I can't find packages for Oracle Instant Client Downloads for Linux on Power Little Endian that relates to, or matches the latest Oracle version in the code, for example, install-instantclient-packages

5. From the downloaded /amp/system-oracle/README.d in the 2.11.1-GA directory, the following setting are required:

ALTER SYSTEM SET max_string_size=extended SCOPE=SPFILE;
ALTER SYSTEM SET compatible='12.2.0.1' SCOPE=SPFILE;

Any other settings required?

5A. No other settings are required.
[Darren] I don't think this applies to the current version (2.14 at the time of writing here), that is, we only have `ALTER SYSTEM SET max_string_size=extended SCOPE=SPFILE;`

6. Since customer is already giving the SYSTEM user account, why doesn't 3scale just execute the commands in 5 instead of asking the customer to set it?

6A.   THREESCALE-8982 has been created for this request.