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Scalable Sequences

18c Scalable Sequences Part III (Too Much Rope)

I previously looked in Part I and Part II how Scalable Sequences officially released in 18c can reduce index contention issues, by automatically assigning a 6 digit prefix to the sequence value based on the instance ID and session ID of the session. We need to be careful and consider this 6 digit prefix if […]

18c Scalable Sequences Part II (Watch That Man)

In Scalable Sequences Part I, I introduced this new 18c feature (although it was hidden and undocumented in previous releases). By adding a 6 digit prefix value that constitutes the first 3 digits for the Instance Id and the next 3 digits for the Session Id, it results in a sequence value that doesn’t always […]

18c Scalable Sequences Part I (Saviour Machine)

One of the problems with populating the value of a Primary Key (or some such), is that they can cause contention, especially in relation to indexes. By having an indexed value that monotonically increases, the right-hand most index leaf block is continually being accessed, which results in a “hot block”, which in turn results in […]