In-depth parsing of Oracle learning notes (chapter I) ____oracle

Source: Internet
Author: User

Chapter One the start and shutdown of the database

1.Oracle boot process, observe the alarm log, first list the parameter file in the default parameters, and then the background process startup process, including PID and OS ID two information, where PID represents the process in the database inside the identifier number, and the OS ID represents the process on the operating system process number.

Note: 9i has no OS id,10g, 11g adds a time tag for each process.

Why there is no pid=1 process.

View V$process View


$ORACLE _home/dbs spfile<oracle_sid>.ora---> Spfile.ora--->init<oracle_sid>.ora none of these three exist, the database will not start

Show parameter spfile See if SPFile file is used, value is not NULL, SPFile file is used

。 Represents Oracle_home, @ represents ORACLE_SID

Under the same oracle_home, Oracle distinguishes an instance according to Oracle_sid, but under different oracle_home, Oracle can create instances of the same oracle_sid, even on the same host.

Instance_name is the initialization parameter, and the default value is Oracle_sid. But different instances can have the same instance_name. Under the same oracle_home, as long as the oracle_sid is different, the database is not instance_name,show parameter instance_name can be seen. However, in the V$instance view, instance_name always stays consistent with ORACLE_SID.

When the listener dynamically registers, the instance in the registration information is the instance_name parameter

The db_name is not more than 8 characters and is registered as the default service name when the listener is dynamically registered.

Rman is very special, and Oracle allows an instance to start without a parameter file, and the database db_name defaults to dummy, which is extreme.

In the Nomount state, you can query the V$parameter view, which comes from the parameter file.


Mount state, control file updated every 3 seconds, heartbeat heartbeat.

If the password file does not exist, the remote user cannot log on to the database using the Sysdba/sysoper identity.

The password file is detected during the Mount phase, but even if the file does not exist, the database can mount normally, and only the error in the alarm log file. (Oracle 9i)

Starting from oracle10g, in the boot process, even if you can not find the password file, the database does not complain, but the password files related to some of the functions can not be used.

lk<oracle_sid> file, lock file. The database is locked at startup and released when closed.

Consistency checksum for Oracle Open phase

1. Check that the checkpoint count (checkpoint CNT) in the header of the data file is consistent with the checkpoint count in the control file, this step checks to confirm that the data file is from the same version, rather than recovering from the backup (since the checkpoint CNT will not be frozen, it will always be modified, Different from the SCN). (Media recovery.) )

If the checkpoint count is passed, the database is checked for a second time.

2. Check the data file Head Start SCN and control files recorded in the file's SCN is consistent, if consistent, you do not need to recover. (Instance recovery.) )

The Listener file (Listener.ora) consists mainly of two parts

1.LISTENER information, including listening protocol, address, port.

2.sid_list_listener information,

Sid_name=plsextproc is the local listener provided by the database default for the external stored procedures contained

Global_dbname matches the service_name in the client request

With the service name, Oracle can completely isolate the client from the server. The client does not need to care about the name of the database and what the instance name is.

Dynamic registration, Pmon process.

Dynamically registered service name, instance state is ready, static is unknown.

Local_listener parameter that specifies which listener the database instance is dynamically registered to. In the Tnsnames.ora file, you can configure resolution for a Non-default port listener.

Remote_listener Remote Registration

Before shutdown abort, it is best to alter system checkpoint to reduce instance recovery time at database startup.

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