The deleteBy*() aswell as getIds() methods cannot be brought back.
Some drivers do not support the getIds(), because (and I agree with) they consider the keys retrieval as a security issue.
Since we keep the Least Common Multiple (LCM) in our Cache platform, these drivers started to be affected in latest *NIX releases (like for example, Memcache 1.6.5+ that does not bring cachedump anymore).
We started to have many reports here because cache was not working, or they were not clearing or even they were getting partially cleared. So we re-worked on Cache package to bring the LCM again.
Based on that, individual drivers like APC may still support the cache Id retrieval, but our approach differed and we can't bring this back. You may override into your own driver (composition) extending our ApcCache and implemented your desired functions.
Marking the ticket as won't fix.