April 2012

Oracle 11g added Extended Statistics support for column groups in order to detect correlated columns for filter predicates using an equal comparison.

Note that Oracle 11g also added the ability to use the number of distinct keys of a composite index as an upper limit for the cardinality estimates for matching column predicates, which means that the optimizer is now capable of detecting correlated columns without the explicit addition of Extended Statistics / Column Groups.

Hosts is the fifth book in the Repairman Jack series by F. Paul Wilson.

Jack is reunited with his sister, just as a new virus threatens to link all human brains into a single collective hive mind, turning the human race into a docile petri dish living for the greater good of the virus.

Perhaps it’s my mood, but this story is just a little too depressing for my tastes. I’m hoping the rest of the series won’t degenerate into this type of doom and gloom. It needs a little more wit and humor to lift it.

Cheers

Tim…

Here is a poll prompted by today twitter talks on the default METHOD_OPT value (which is ‘for all columns size auto’ since 10g) and automatic statistics gathering job (auto-task since 11g). CBO development team suggests to use the default job to gather statistics with default options. Do you use the job exactly this way with real production databases? I’m very interested to see some numbers. Please share the poll link http://poll.fm/3n7pn so that more people vote. Thanks.

おもしろった！