Various "Names" in oracle"

Oracle database name: refers to the name of the oracle database, which uniquely identifies a database in a domain. The database name is specified by the db_name initialization parameter. The database name can contain up to 8 characters (numbers, underscores, #,$). It must be the same as the name specified in create database. When multiple databases exist, the database name should be consistent with the instance name to avoid confusion between the instance and the database. In the RAC environment, the database names of all instances must be the same, and the names of the backup database and the primary database should also be the same.

SQL> show parameter db_nameNAME TYPE VALUE------------------------------------ ----------- --------db_name string wilson

 

Database name: wilson (2) instance name (instance name): The oracle instance is composed of SGA and oracle background processes. The instance name refers to the instance name. It is specified by instance_name in the initialization parameter file and uniquely identifies the instance. In a single-instance architecture, the Instance name is generally the same as the database name. In the RAC environment, multiple instances correspond to one database. The instance name is the SID we frequently raise.

SQL> show parameter instance_nameNAME TYPE VALUE------------------------------------ ----------- --------instance_name string WILSON

 

Instance name: WILSON (3) database domain (database domain Name): database domain name is the network domain name. After the database is created, changing the value of the initialization parameter db_domain does not affect the resolution of the global database name or Database Link name. The alter system method cannot be modified. Alter database should be used for modification, and the modification will not be reflected in db_domian, but in global_name.

SQL> show parameter db_domainNAME TYPE VALUE------------------------------------ ----------- --------db_domain string

 

I didn't set the database domain name because my database was used for local learning and testing. (4) global database name (global database name): uniquely identifies a database in the format of database_name.database_domain. Because the database names in different regions may be the same, but the database names in the same region cannot be the same, you can use database_name.database_domain to uniquely identify a database. View the data dictionary view global_name to determine the global database name.

SQL> select * from global_name;GLOBAL_NAME-----------------------------------ORACL

 

(5) Modify db_domain by modifying global_name

SQL> alter database rename global_name to   wilson.dave.sun;Database altered.

 

View changes

SQL> select * from global_name;GLOBAL_NAME-----------------------------------wilson.dave.sunSQL> show parameter db_domainNAME TYPE VALUE------------------------------------ ----------- -----------db_domain string

 

Although the value of db_domain is empty, the global database name has been changed. However, db_domain does not seem to have been changed. (6) database service name (database service name): for the client, the database is only a service logically. A database instance can have multiple database service names. Each database service name is used by a group of different clients. Each database service name can also correspond to multiple database instances. Each database is identified by a database service name. The database service name is determined by the initialization parameter service_name. The default and global database names are the same ~~~