Mouhssine,
Yes, not "decompressing" the HCC tables after being provisioned into a VDB is going to result in an Oracle error (i.e. "ORA-64307" which indicates that HCC is not supported on non-Oracle storage).
The appropriate hook to use would be a "Configure Clone" hook, which fires after the initial provision of the VDB and after each refresh. The documentation for using hooks with Oracle starts on
this page online here.
Within the hook, the environment variables for ORACLE_HOME, ORACLE_SID, ORACLE_BASE and a few others (as
documented online here) allow you to run SQL*Plus easily from within UNIX/Linux shell-script from the hook.
So, within the "Configure Clone" hook, you can run ALTER TABLE ... MOVE [ PARTITION ] ... COMPRESS BASIC to make those HCC tables usable in the VDB.
Hope this helps!
-Tim