11g benefits

Posting from the UKOUG (UK Oracle User Group) conference. A couple of useful details from Tom Kyte’s technical keynote on “Things which might be in 11g but we’re not making any promises and you can’t hold us to it”.

The optimizer will be extended to allow us to collect some statistical information about correlated columns. This should help the optimizer to deal with combining predicates like: “Orders made in the last two weeks” with “Orders that have not yet been delivered” – if they’re recent orders, they’re more likely to be undelivered. I’m looking forward to seeing how far the Optimizer team has got with handling this rather difficult problem.

Partition handling: one of the current irritations for partitioning is that you have to disable referential integrity between partitioned tables if you want to drop old partitions. (Drop child partition Jan2001, followed by an attempt to drop the “obviously matching” parent partition Jan2001 currently results in Oracle error “ORA-02266: unique/primary keys in table referenced by enabled foreign keys”). 11g will give us the ability to declare that the partitioning of the child table is dependent on the partitioning of the parent table, and therefore guaranteed to be in-synch with the parent table. Apart from handling the drop partition problem, this should also help to avoid accidents that manage to disable partition-wise joins.