Openworld day 3

Yesterday was another day of good quality sessions at OpenWorld.  Yes its true that there are many sessions that could only be described as pure marketing, but with a little effort, there are gems in the agenda !

It started with partitioning facilities that are coming in 12c.

Interval/Reference partitions will be supported, although no word on whether you can have subpartitions under interval based range partitions.  Time will tell.

One of the nice things was the CASCADE option coming for truncate/exchange partition.  In the past, when you had foreign keys between tables (as of course we always should :-)), then truncate (being a DDL) would require a lot of manual FK maintenance before and after the truncate command.

This restriction has been lifted to a reasonable degree in 12c.

Next up was a session on optimizer hints by Maria Colgan, who is product manager for the optimizer team.  As she quoted: “I’m the chief apologiser for the Oracle optimizer”.  Which is a bit harsh to be honest – I’ve generally found most optimizer issues are due to lack of understanding rather than any particular lack of function within the product itself.

The session on hints was good, in particular, a strong stress toward trying to implement “hints” via baselines rather than code changes.  I’m not entirely sure I agree with that policy, given that a hint in the code is “self-documenting” whereas a baselines is just that little bit less visible.

Another thing coming in the 12c optimizer is “adaptive execution plans”, namely, the database at run time may recognise that the plan chosen as parse time was possibly not the best one, and may change it on the fly.  Sounds impressive, but also sounds a little risky in terms of ensuring consistency of performance.  Time will tell.

Finished the day with some clam chowder !  Yum.