December 11, 2010
In the interest of interesting quotes, a quote that I found in the “Oracle Tuning the Definitive Reference Second Edition” book on page 828:
“When the index can no longer split because the owner block is full, Oracle will spawn a whole new index level, keeping the index tree in perfect logical and phyical balance. Deletes are a different story. Physically, Oracle indexes are always balanced because empty blocks stay inside the tree structure after a massive delete. Logically, Oracle indexes are not self-balancing because Oracle does not remove the dead blocks as they become empty. Figure 16.9 shows an Oracle index before a massive delete…”
What, if anything, is wrong with the above quote? Please keep in mind that the focus of this blog is on the technical content, and learning from that technical content. Please stay positive in your responses (before answering, first take a look at page 727 to see if these two sections of the book are related – note that Richard Foote’s PDF file listed below seems to address page 727 of this book).
While my review of the book only provides an in-depth technical review of the first 200 pages of the book, this blog article series will dig into some of the pages that were not specifically included in the review.
The point of blog articles like this one is not to insult authors who have spent thousands of hours carefully constructing an accurate and helpful book, but instead to suggest that readers investigate when something stated does not exactly match what one believes to be true. It could be that the author “took a long walk down a short pier”, or that the author is revealing accurate information which simply cannot be found through other resources (and may in the process be directly contradicting information sources you have used in the past). If you do not investigate in such cases, you may lose an important opportunity to learn something that could prove to be extremely valuable.
Other pages found during a Google search of the phrase:
- The previous edition of the book
- http://richardfoote.wordpress.com/2007/12/12/why-are-there-so-many-oracle-related-myths-the-inconvenient-truth/ (excellent article, includes a link to Richard Foote’s Index Internals – Rebuilding the Truth PDF)
- http://www.fullinterview.com/allpaperpresentations/oracle/Database%20Design%20A%20Guided%20Approach.doc (interesting document, or just repeating sections of this book?)
- http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:678824574412 (may not be closely related)