# Oracle Sequences: RAC

The series so far:

Oracle sequences: The basics Oracle sequences: RAC

In my first article on Sequences, I reviewed the fundamental reason why Oracle Corp. introduced the mechanism (i.e. synthetic/surrogate keys) and the mechanical threats (cache size and index contention) that still had to be addressed by the developer/DBA. In this article, I’ll spend most of my time explaining how the problems can get worse (and be addressed) as you move from single-instance Oracle to multi-instance Oracle (RAC). I’ll end the article by mentioning the newer features of sequences that appeared in the upgrades from 12c to 19c, emphasizing one