Basic knowledge of oracle architecture (Entry level)

Author: Lu Yang
To learn about oracle, we 'd better first understand the Oracle framework. In this way, we have an overall understanding of Oracle, and it has the role of creating a high-level architecture.
1. Physical Structure (composed of control files, data files, redo log files, parameter files, archive files, and password files)

The data in a database is stored in physical files on the disk. When used, the data is transferred to the memory.
The control file, data file, redo log file, trace file and warning log (trace files, alert files) are database files;
The parameter file password file is a non-database file.

1.1 data files: data files that store data. data files typically represent the volume of an Oracle database determined by the disk space and quantity they use.
For performance reasons, each type of data is stored in a corresponding file or a series of files, which are placed on different disks.
Types:
. Data dictionary. data
. Redo data. index
. Temporary data, etc.
1.2 control file: contains the necessary information to maintain and verify the integrity of the database. For example, a control file is used to identify data files and redo log files. A database requires at least one control file.
Control File Content
. Database Name
. Tablespace Information
. Names and locations of all data files
. Names and locations of all redo log files
. Current Log serial number
. Checkpoint Information
. Redo log and archive current status information
Use of Control Files
The control file directs Oracle to other parts of the database file. When an instance is started, Oracle reads the name and location of the control file from the parameter file. When the database is installed, Oracle opens the control file. When the database is finally opened, Oracle reads the list of data files from the control file and opens each file.
1.3 redo log file: contains the changes made to the database, so that data recovery can be enabled in case of a fault. A database requires at least two redo log files.
1.4 Trace Files and warning logs (Trace Files and Alert Files)
Each background process running in the instance is connected to a trace file. Trace file records the information of major events encountered by background processes.
Alert Log is a special trace file. Each database has a trace file that synchronously records database messages and errors.
1.5 parameter file: contains a large number of settings that affect the functions of Oracle database instances, as shown in the following settings:
. Locating Database Control Files
. The amount of memory that Oracle uses to cache data read from the disk
. Select the default optimizer.

Perform two important functions related to database files