2.1 ORACLE Server

When your application accesses the Oracle server over the networkProgramAssign user processes, and the server assigns them server processes, and all SQL operations applied by the customer are finally executed by the server process.

Oracle Server = routine + database.

 

1. Routine

Routine = memory structure + background process

Memory Structure (SGA ── system global area, system global area) = Data High-speed cache + redo log buffer + sharing pool

Background process = SMON + pmon + dbwr + ckpt + lgwr +...

You can obtain information about the current instance by querying the dynamic performance view v $ instance.

SQL> Conn/As sysdba
Connected.
SQL> select instance_number, instance_name, status from V $ instance;

Instance_number instance_name status
-------------------------------------------
1 orcl open

 

2. Database

Database = data file + control file + redo log

You can obtain information about the current database by querying the dynamic performance view v $ database.

SQL> Conn/As sysdba
Connected.
SQL> select dbid, name, log_mode, current_scn from V $ database;

Dbid name log_mode current_scn
------------------------------------------
1189837078 orcl noarchivelog 1228375