Related Files used by the Oracle database after creation

This article mainly describes the relevant operating system physical files that can be used by the Oracle database after creation, as well as the Oracle logical components, and other related operating files, at the same time, this article also gives a detailed description of the actual application of these related files.

Oracle physical components

The physical component of the database refers to the physical component of the database from the physical perspective, that is, the physical file of the operating system used after the Oracle database is created. Oracle Database physical files can be divided into three types: data files, log files and control files.

Data File: SYSTEM01.DBF/SYSTEM01.ORA)

Data Files) Files used to store database Data. Data such as tables and indexes are stored in data files. Each Oracle database has one or more physical data files. A data file can only be associated with one database.

Log File: REDO01.LOG)

Log File Redo Log Files) is used to record changes made to the database. Log files are mainly used to implement database recovery when the database fails.

Control File: CONTROL01.CTL)

Control Files) are binary Files used to record the physical structure of the database. This file contains necessary information for maintaining and Verifying database integrity.

Logical components of Oracle

The logical component of a database is a logical component used to analyze the database. Oracle describes the logical structure through data dictionary storage. The logical components of the Oracle database include

Tablespace, segment, partition, block, and user mode.

TABLESPACE ):

Tablespace is the largest logical unit in a database. Oracle databases use tablespaces to combine related logical components. An Oracle database must contain at least one tablespace. Each tablespace is composed of one or more data files. A data file can only be associated with one tablespace.

Each database has a tablespace named SYSTEM, that is, the SYSTEM tablespace, which is automatically created during database creation or database installation, it is used to store data dictionary tables, program units, processes, functions, packages, and triggers of the system.

The syntax for creating a tablespace is as follows:

The syntax of the extended data file is as follows:

SEGMENT ):

A tablespace contains one or more segments. A segment is a specified type of logical storage structure. A segment consists of multiple zones. For example, the following four types of segment structures are commonly used:

Data Segment -- index segment -- rollback segment -- temporary segment)

Area EXTENT ):

The partition is the minimum unit for disk space allocation. The disk is divided by zone. At least one zone is allocated each time. A partition allocates space for segments. It consists of consecutive data blocks. A zone consists of multiple data blocks, which are the smallest unit for data read/write operations.

Data block ):

Data blocks are the smallest data organization and management units in the database. Data in the Oracle database is stored in data blocks. The data block value range is 2 kb ~ Between 64 KB.

SCHEMA ):

Mode is a general term for the database objects created by users. Any database objects in the Oracle database belong to a specific user. A user and its objects are called modes. Schema objects include tables, views, indexes, synonyms, sequences, processes, and packages. A user is associated with a mode with the same name, so it is also called a user mode.