Dominic Brooks published a note recently about some very nasty SQL – originally thinking that it was displaying a run-time problem due to the extreme number of copies of the lnnvl() function the optimizer had produced. In fact it turned out to be a parse-time problem rather than a run-time problem, (more...)
The singer is Canadian astronaut Commander Chris Hadfield who has been tweeting and posting pictures from space – be careful, you (more...)
Here’s a quick and dirty script to create a procedure (in the SYS schema – so be careful) to check the Hakan Factor for an object. If you’re not familiar with the Hakan Factor, it’s the value that gets set when you use the command “alter table minimize records_per_block;”.
Cost Based Oracle – Fundamentals (November 2005)
But the most interesting function for our purposes is sys_op_countchg(). Judging from its name, this function is probably counting changes, and the first input parameter is the block ID portion (object_id, relative file number, and block number) of the table’s rowid, so the (more...)
I’m about to make a serious move into online webinars, and as a warm-up exercise I’ll be doing a couple of one-hour free events on Friday 17th May.
I’ll be talking through a Powerpoint presentation called “Smarter Statistics in 11g” twice, once at 2:00 pm BST, and again at 6:00 (more...)
Materialized views open up all sorts of possibilities for making reporting more efficient – but at the same time they can introduce some “interesting” side effects when you start seeing refreshes taking place. (Possibly one of the most dramatic surprises appeared in the upgrade that switched many refreshes into “atomic” (more...)