Oracle Database Internal Architecture

Oracle Database internals consist of two main components: the database and the Oracle instance. The database is the static part of the Oracle system, and the Oracle instance is the memory structures and the Oracle background processes that are started when the database is started. The Oracle Database internal architecture is shown in Figure 19-1.

FIGURE 19-1 Oracle Database internal architecture

Database

The Oracle Database includes all the files that constitute the dataset. This includes the datafiles, control files, online redo log files, and offline archive log files. When an Oracle system is started, the database files are associated with the Oracle instance, and any operations the user performs are recorded in the appropriate files at the operating system level. The following definitions will clarify the different files that constitute the Oracle Database.