I have just posted a lengthy article about how Oracle uses rowid. It starts with talking about blocks , and how they work. Then I discuss how rowid are used and represented in symbolic dumps. Normal uses such as index linking to a data segment as well as migrated and chained rows are discussed. The document finishes with a brief discussion on how ITL works on the block and the relation between ITL and locking on the original block a row was first placed on (before it was migrated or chained).
This article is the basis for the presentation I will hold tomorrow at the Orcan conference. If you will join us for the conference, come see the presentation. ROWID and block dumps are pretty fascinating stuff. This is one area where Oracle’s internals really impresses. Learning how Oracle built the database usually teaches me a few new things about how interesting problems can be solved in clever ways.
This blog post will be the permanent place for comments, updates, and discussions about this document. I intend to translate this document to English soon, as I have been asked to provide an excerpt of this for publication in the US.