Summary

In this chapter, we broke down an Oracle database into its smallest pieces—both logically and physically. We examined common threads on how to track transactions by Xid, SCN, and Timestamps. The physical components should be very clear to you as well—undo segments, redo logs, archived logs, and database files. And most important of all: how transactions travel through the physical parts of the database, from when the end user types in a change, to a row in a table identified by a rowid on a particular data block on a physical data file.

Several utilities were covered along with appropriate scenarios and suggested uses:

• Oracle's RDBMS SQL command dump block

• Oracle's RDBMS Log Miner utility

• Flashback Transaction Query and Backout

• Unix strings command

This chapter is a building block on which you keep adding as you continue through the book. The information in the next chapter (Chapter 4, Achieving Maximum Uptime) is based on the Maximum Availability Architecture standard created by Oracle...