Oracle 11g database Startup and shutdown

ORACLES11 the startup state of the database

ORACLE11G must go through three states at boot time: Nomount,mount,open.

Nomount: Only open the DB instance in this state, read the parameter file.

MOUNT: Opens the control file according to the parameter file information. Reads various information in the control file, such as the data file location, the log file path, but does not open the data file.

Open: Opens the data file and carries out a series of inspection work.

Start the database:

[Email protected] oracle]$ sqlplus/nologsql> connect/as sysdbaconnected.sql> Startup

The display database has successfully started and entered the open state.

ORACLE instance started. Total System Global area 1586708480 bytesfixed size 2213736 bytesvariable size 939526296 bytesdatabase buffers 637534 208 Bytesredo buffers 7434240 bytesdatabase mounted. Database opened.

To close the database:

sql> shutdown immediate;database closed. Database dismounted. ORACLE instance shut down.

Shut down the database and start the process instead, take three actions in turn, close, dismount, shut down.

If you want to manually start each state sequentially, use the following command:

sql> startup Nomount; Sql> ALTER DATABASE Mount; sql> ALTER DATABASE open;

Database files

The database is mainly composed of data files, control files, redo log files. These files are the core of the database.

Data files: Data files contain the actual data in the database. is the final location where the data is stored.

Control files: Contains information that maintains the database and verifies the integrity of the database. It is a binary file.

Redo log files (redo files): Redo log files contain records of changes to the database that are used for data recovery in the event of a failure.

Other files:

Parameter file (parameter files): The parameters file defines the attributes of the DB instance, the allocated memory, and the buffer size information.

Password file: Authorizes the user to start and close the DB instance, storing the user name and password.

Archived log files: Archived log files are offline backups of log files that may be used when data recovery occurs after a failure.

Database parameter settings

The share pool is the parsed result data for the cached SQL code, including the library cache (Libray cache) and the data dict cache.

Library cache (Libray cache): Stores the most recently used SQL and PL/SQL statements.

Data dict cache: Data files, tables, indexes, columns, users, permissions information are stored.

The size of these two cache regions determines the response time of a database query, but it cannot be directly modified by parameters, and the buffer size can be adjusted indirectly by resizing the shared pool.

To set the shared pool size:

Sql> alter system set shared_pool_size=16m; System altered. Sql> Show parameter Shared_pool_size;name TYPE VALUE------------------------------------------------------------ -----------------shared_pool_size Big Integer 16M

The database buffer cache stores data that is most recently read from the data file or that needs to be written back to the database after the user changes.

Oracle sets the size of the database cache using Parameters Db_block_size and db_block_buffers. The product of the two is the size of the cache, and Db_block_buffers represents the number of databases.

Query the size of the database block, the value shown here is 8192B, that is 8KB:

Sql> Show parameter Db_block_size;name TYPE VALUE--------------------------------------------------------------- --------------db_block_size integer 8192

To view database buffer information:

Sql> show SGA; Total System Global area 1586708480 bytesfixed size 2213736 bytesvariable size 939526296 bytesdatabase buffers 637534 208 Bytesredo buffers 7434240 bytes

The SGA is the automatic management of the database.

This article is from the "Trying" blog, make sure to keep this source http://tryingstuff.blog.51cto.com/4603492/1978758

Oracle 11g database Startup and shutdown