Compared to the buffer cache and shared pool memory structures, the redo log buffer is very straightforward. While Oracle continues to enhance the redo log buffer architecture, the central idea has remained the same: buffer and batch redo changes to improve log writer background process efficiency and enable extremely quick commit times.

Figure 8-3 is a highly abstracted view of the redo log buffer and is more accurate for Oracle releases prior to Oracle9i Release 2, but it is a great way to gain a solid conceptual view of the redo log buffer and how it works. The redo log buffer is a circular first-in/first-out (FIFO) queue structure. The structure also utilizes two pointers:

* The last allocation pointer designates the end point for the last redo log buffer space allocation and also points to the beginning of the next allocation point.