Starting with version 7.0, SQL Optimizer uses a new Windows registry location and the entire registry structure has been revised. If you have been using SQL Tuning version 6.1.2. or earlier or SQL Optimizer 3.8.5 or earlier, you may want to review the option settings and reselect your preferences.
In a Side-by-Side Installation
Starting with version 7.5, you can install SQL Optimizer versions side-by-side. If installed separately, each new version has its own data directory. The data directory path now includes the version number. The following is the default data directory path in SQL Optimizer 9.2.2:
C:\Users\<user>\AppData\Roaming\Quest Software\Quest SQL Optimizer for Oracle\<version number>\<data directory>
A known Oracle issue causes the database connection to fail when using a pre-11g client and when the application directory path contains parentheses. In a 64-bit environment, the default directory for a 32-bit application is "C:\Program Files (x86)\". In this situation, if you use the default directory when installing SQL Optimizer, you cannot connect to Oracle. To work around this issue, install SQL Optimizer into a directory path that does not contain parentheses (if you are using a pre-11g client).