In the previous chapter, we explored the database side of the Oracle architecture. We said that a database is made up of datafiles. We have not as yet discussed what makes up the datafile itself. In this section, we break down the way that Oracle stores data within a datafile at the micro level.
During our discussion of the database buffer cache and database writer process, we mentioned that Oracle reads data from a disk and writes it into memory for faster manipulation. Now that we've defined a number of terms involved, we can more accurately say that the DBWn process reads blocks of data from datafiles and writes them into the database buffer cache in the SGA in the form of database buffers. We've defined the destination in memory for the data during this operation—the database buffer cache. We now want to take a closer look at the source of the data—the database block. The database block is the smallest atomic...