| Lesson 8 | Oracle file structures |
| Objective | Review database physical files. |
Database Physical Files after installing Oracle 12c
When you install Oracle12c on a Windows Machine, which files are created on your system?
When you install Oracle 12c on a Windows machine, a number of files and directories are created on your system. Some of the most common files and directories that are created during an Oracle 12c installation on Windows include:
Note that the exact set of files and directories that are created during an Oracle 12c installation on Windows may vary based on the specific installation options that are selected, and the version of the operating system that is being used.
If you choose the default installation, you will end up with a directory structure called the Oracle Home that consists of subdirectories and files. The following image shows a partial listing of my installation.
- Oracle Home directory: This is the main directory where the Oracle software is installed, and it typically contains subdirectories for the database software, client software, and various other components.
- Binaries: The Oracle Home directory contains a number of executables and shared libraries that are used to run the database and various other components of the software.
- Configuration files: The Oracle Home directory contains a number of configuration files, such as the tnsnames.ora file, which is used to define the connection information for the database, and the listener.ora file, which is used to configure the Oracle Net Listener.
- Log files: Various log files are created during the installation process, including installation logs, alert logs, and trace files, which can be used to diagnose problems and monitor the performance of the database.
- Database files: The Oracle Home directory also contains the database files, including the control files, datafiles, and redo log files, which are used to store the data and metadata for the database.
- Oracle Registry: An Oracle Registry is created during the installation process, which contains information about the installed components and their configuration settings.
- Windows Services: Oracle 12c creates several Windows Services during the installation process, including the OracleService instance, which is used to start and stop the database, and the Oracle Listener service, which is used to listen for incoming connections.
Note that the exact set of files and directories that are created during an Oracle 12c installation on Windows may vary based on the specific installation options that are selected, and the version of the operating system that is being used.
If you choose the default installation, you will end up with a directory structure called the Oracle Home that consists of subdirectories and files. The following image shows a partial listing of my installation.
My Oracle home is C:\ORACLE8. My database files are located in the directory C:\ORACLE8\DATABASE. The following diagram shows the files found in a typical Oracle installation.
- Contains parameters that specify the database block size, the amount of memory to use for the Shared Global Area (SGA), and that control other aspects of how the database instance operates.
- Keeps track of all the files that make up a database.
- Stores a log of all changes made to the database (the redo log), that is used in the event that the database needs to be recovered.
- Stores a log of all changes made to the database (the redo log), that is used in the event that the database needs to be recovered.
- Tablespaces are logical storage structures that contain table and index data. Oracle allows you to map a tablespace onto one or more physical files.
- These are the files that hold the data for tables and indexes. They are the reason all the other files exist.
- These are the files that hold the data for tables and indexes. They are the reason all the other files exist.
- A group of one or more redo log files that Oracle treats as one. Oracle writes the same information to each file in a group.
- A group of one or more redo log files that Oracle treats as one. Oracle writes the same information to each file in a group.
- This is the location to which Oracle copies redo log files when they are filled.
There are two
V$ views that you can use to query basic information about your database and to find files on disk. Examples of V$DATABASE and V$DATAFILE are listed below.
These are simplistic examples from a small database. The importance of these
V$ views will become more relevant when we start talking about our backup and recovery options later in this series of courses. If you have the opportunity, I would recommend that you run these views against your own production databases. this will provide you with a better understanding of how your databases are structured. The next lesson wraps up this module.