Área que o Orade Database Server aloca em memória e compartilha informações. Principais componentes:
System Global Area
Estrutura de memória (Redo Log Buffer, Data Base Cache, Shared Pool e Large Pool) que facilita a troca de informações entre os clientes. Cada estrutura que a constitui possui uma finalidade diferente:
– Redo Log buffer: Armazena e registra alterações feitas, como instruções de INSERT, DELETE e UPDATE;
– Database Buffer Cache: Armazena os dados que foram utilizados recentemente pelo Banco de Dados;
– Shared Pool: Armazena todos os comandos (recentes) utilizados;
– Large Pool: Área adicional para processar em memória grandes requisições de E/S.
Program Global Area
Auxilia na execução de processos, armazenando informações de Variáveis, Áreas de Classificação e Cursores de Blocos PL/SQL.
Background Processes
Serviços do Sistema Operacional que uma Instância utiliza. Esses serviços variam desde a Gravação em Disco até a Geração de Arquivos de Redo Log File, denominados ARCHIVES, que tem como finalidade a recuperação (RECOVERY) do Banco de Dados.
Além desses componentes, toda instância conta com um arquivo principal chamado INIT.ORA. Esse arquivo contém diversos parâmetros de configuração. O caminho padrão é ORACLE_HOME\server\dbs.
INIT.ORA
###########################################
# Copyright (c) 1991, 2005, Oracle. All rights reserved.
######################################################################################
# Cursors and Library Cache
###########################################
open_cursors=300###########################################
# Database Identification
###########################################
db_name=XE###########################################
# Diagnostics and Statistics
###########################################
background_dump_dest=C:\ORACLE\DBXE10G\app\oracle\admin\XE\bdump
core_dump_dest=C:\ORACLE\DBXE10G\app\oracle\admin\XE\cdump
user_dump_dest=C:\ORACLE\DBXE10G\app\oracle\admin\XE\udump###########################################
# File Configuration
###########################################
control_files=("C:\ORACLE\DBXE10G\oradata\XE\control.dbf")###########################################
# Job Queues
###########################################
job_queue_processes=4###########################################
# Miscellaneous
###########################################
compatible=10.2.0.1.0###########################################
# Processes and Sessions
###########################################
sessions=20###########################################
# SGA Memory
###########################################
sga_target=140M###########################################
# Security and Auditing
###########################################
audit_file_dest=C:\ORACLE\DBXE10G\app\oracle\admin\XE\adump
remote_login_passwordfile=EXCLUSIVE###########################################
# Shared Server
###########################################
dispatchers="(PROTOCOL=TCP) (SERVICE=XEXDB)"
shared_servers=4###########################################
# Sort, Hash Joins, Bitmap Indexes
###########################################
pga_aggregate_target=40M###########################################
# System Managed Undo and Rollback Segments
###########################################
undo_management=AUTO
undo_tablespace=UNDO###########################################
# Backup and Recovery
###########################################
DB_RECOVERY_FILE_DEST_SIZE = 10G
DB_RECOVERY_FILE_DEST = C:\ORACLE\DBXE10G\app\oracle\flash_recovery_areaos_authent_prefix=""
