Yesterday, I blogged about a good white paper I found from Maria Colgan of Oracle Corp relating to the CBO. I also discovered another good paper. This one discusses all of the CBO-related enhancments for Oracle 12c. You can find this paper here.
Optimizer with Oracle Database 12c
This one is a really good read. I’ve been looking forward to Adaptive Query Optimization, especially Adaptive Statistics since 12c was released. I’m still at least 1 year away from putting 12c into production. But when we get there, I think this will be a big benefit from us. Many of my poorly performing SQL statements are often “fixed” by simply updating the statistics. Oracle hasn’t correctly identified the stats as stale and the SQL performs sub-optimally. I’m looking forward to Oracle 12c where it can detect this on-the-fly and use a better plan for the next SQL execution.
One thing I could not find in this paper was where Oracle 12c will perform UNION statements in parallel. Maybe I missed that.
In my previous research, I was not able to find a few new 12c features that this white paper does discuss
– Online Statistics Gathering – for some database operations, since the database is already reading the data, Oracle will generate stats as it goes, saving time for later.
– New reporting for DBMS_STATS – Now you can see what DBMS_STATS did during its regular stats gathering job.