Oracle Series one, basic terminology

Beginners often confuse terminology such as Oracle instances, Oracle databases, and Oracle servers.

Typically an Oracle database can be divided into two parts

1. Example (instance)

An instance is a non-fixed, memory-based, basic process and memory structure. When the server shuts down, the instance does not exist.

2. Databases (database)

A database refers to fixed, disk-based data files, control files, log files, parameter files, and archived log files. In general, the Oracle database is a database that contains one instance.

Database server

Oracle servers generally refer to the Database software components (SQLPLUS,OEM,EXP/IMP) and the three main parts of the instance and database, which are composed of all the software installed on the server and the instances after the successful startup.

System structure

After the SQL command is issued from the client, the Oracle server process responds, parses, compiles, executes in the memory area, writes the modified data to the database file, modifies the database information to the log file, and returns the results of the SQL execution to the client

Table Space

Disk logical space for objects such as database tables, indexes, rollback segments, and so on are called tablespaces

Data files

DataFile is a file that holds user application data and internal data from the Oracle system. An Oracle database consists of table spaces, and each tablespace can contain one or more data files.

Temporary table space

Temporary tablespace is a special table space that Oracle systems use to store sorting.

Control files

A control file is an internal binary file that stores Oracle instance information, data files, and log files

Log file

Log files divided into redo log files (Redo log file) and archived log files

System global Area (SGA)

The System Glocal area consists primarily of three parts: a data buffer, a log buffer, and a shared pool.

Data dictionary

A data dictionary is a set of tables that hold important information about an entire database instance, most of which are attributed to the SYS user.

Oracle Series one, basic terminology