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System tablespace
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Sysaux tablespace
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Undo tablespace
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Temporary tablespace
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Default permanent tablespace
Physical Database Structures
The Oracle database consists of the following three main types of files:
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Data files: These files store the table and index data. Can belong to only one database
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Control files: These files record changes to all database structures. Names and locations of the data files, redo log files, current log sequence numbers, backup set details, and the all-important system change number (SCN), which indicates the most recent version of committed changes in the database. Every database has one control file.
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Redo log files: These online files contain the changes made to table data. Redo log files contain the following information about database changes made by transactions:
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Indicators specifying when the transaction started
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The name of the transaction
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The name of the data object that was being updated (e.g., an application table)
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The "before image" of the transaction (the data as it was before the changes were made)
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The "after image" of the transaction (the data as it was after the transaction made the changes)
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Commit indicators that indicate whether and when the transaction completed
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The SPFILE (init.ora is no longer recommended)
When you create a new database, you specify the initialization parameters for the Oracle instance in a special configuration file called the server parameter file (SPFILE). You can also use an older version of the configuration file called the init.ora file but the SPFILE is recommended. Note the SPFILE is a binary and not directly editable. Location is ORACLE_HOME/dbs.
The Password File
The password file is an optional file in which you can specify the names of database users who have been granted the special SYSDBA or SYSOPER administrative privileges, which enable them to perform privileged operations, such as starting, stopping, backing up, and recovering databases.
The Alert Log File
Every Oracle database has an alert log named alertdb_name.log (where db_name is the name of the database). The alert log captures major changes and events that occur during the running of the Oracle instance, including log switches, any Oracle-related errors, warnings, and other messages. Location specified in the BACKGROUND_DUMP_DEST initialization parameter, or defaults to $ORACLE_HOME/rdbms/log on HP.
To locate:
SQL> SHOW PARAMETER background dump
NAME TYPE VALUE
-----------------------------------------------
background_core_dump string partial
background_dump_dest string /u01/app/oracle/product/10.2.0/db_1/orcl/bdump
Trace Files
Oracle requires that you specify three different trace file directories in your initialization file: the background dump directory, the core dump directory, and the user dump directory.
BACKGROUND_DUMP_DEST parameter.
CORE_DUMP_DEST parameter.
USER_DUMP_DEST initialization parameter.
Oracle Managed Files
The OMF feature aims at relieving DBAs of their traditional file-management tasks. When you use the OMF feature, you don't have to worry about the names and locations of the physical files. Instead, you can focus on the objects you're creating. Oracle will automatically create and delete files on the operating system as needed.
