Few days ago Oracle accepted my Oracle ACE Director nomination! In this short post I would like to thank the people that actively supported the nomination.
The values provided by the “parse count (total)” and “session cursor cache hits” statistics are subject to several bugs. And, what’s worse, for years Oracle didn’t care to fix it. This is my impression, at least.
Then, when few weeks ago I read in the Oracle Support note 13837105.8 (more...)
This is a short post about a strange behavior I discovered today…
The fact is that it is not really possible to use the named notation with the SEM_MATCH table function. In fact, even though the parameter’s names can be specified, the order of the parameters overrides the specification done (more...)
Premature optimization, (probably) because of Donald Knuth’s famous line “premature optimization is the root of all evil,” (see Structured Programming with go to Statements) is, at the very least, a controversial topic. The misconception based on that particular quote is that a programmer, while writing code, should ignore optimization altogether. In my opinion this is wrong. To put the quote in context, let’s have a look to at the text that precedes and follows it:
There is no doubt that the grail of efficiency leads to abuse. Programmers waste enormous amounts of time thinking about, or worrying about, the (more...)
The 11th and 12th of December and, therefore, the CBO Days in Zurich are approaching. Given the high quality of the speakers that accepted my invitation and the number of people that decided to attend the event, in my opinion it will be a blast! By the way, if you are interested in attending the event, do not wait any longer. In fact, from the 80 available seats, 75 are taken.
Here is a preview of the agenda:
Tuesday 11th December
- 09:00 – 09:10: Welcome and Introduction, Christian Antognini
- 09:10 – 10:30: The History of the Oracle Optimizer, Maria Colgan
In the last post I discussed a test case generating lot of child cursors. Today I wanted to show you, for the very same test case, that in 11.2 the parse time might increases linearly with the number of child cursors per parent cursor. This is the expected behavior. In fact, to check whether an already available child cursor can be reused, the list of child cursors must be scanned. And, in case no one of the already available child cursors is compatible, every entry needs to be probed.
Note that to generate the previous chart I simply run, (more...)