Please note that, Informatica 9.1 does not support Oracle 12C database. Starting from Informatica 9.6.1 version, Oracle 12C is supported for domain DB, repository DB and as source/target.
Please refer PAM document section for more information:
Oracle 12C is certified from informatica 9.6.1.
My two cents...
If you are referring to Domain and Repository Database then it's not certified i.e Infa 9.1.0 with Oracle 12c.
If you are referring to Source & Target Database then it totally depends on connection drivers (Native and ODBC).
May I add something to Adil's remark:
Accessing Oracle databases via ODBC is NOT supported by Informatica for a simple reason: there are native connectors available for Oracle, so Informatica certifies its software (in particular PowerCenter) solely with the native drivers and NOT with ODBC. You might encounter all sorts of unpleasant effects when using ODBC with Oracle, and then you're on your own.
For source and target databases using an Oracle 11g client with PowerCenter should be safe to use with Oracle 12c database instances, as long as you don't use SQL overrides for your sources / targets. This assumption is a consequence of the fact that - as far as I know - Oracle certifies the 11g client for use with 12c databases, this is NOT an official statement.
Nico, you are always welcome to provide your expert advice...
Ya ,agree if Oracle certifies the 11g client for use with 12c databases.
We had similar scenario wrt Teradata connectivity. (i.e. Infa 9.1 v/s Teradata 14.10.)
We used 13.10 Client to connect Teradata 14.10.