-Specific initialization parameters that affect ORACLE System Performance

Source: CCID

The initialization parameters that affect Oracle system performance are as follows::

SGA (system global zone)
The system global zone (SGA) is a memory segment allocated to the database containing an oracle instance.
1. It mainly includes the database buffer cache ),
The redo log buffer ),
The shared pool ),
The data dictionary cache and other information.

Db_block_buffers 
1. Data High-Speed Buffer
2. The accessed data is stored in this memory area. The larger the parameter, the more likely Oracle will find the same data in the memory, which accelerates the query speed.
3. db_block_buffers is in block units. If db_block_size = 2 K and db_block_buffers = 3200, the memory occupied is 3200*2 K = 6400 K.

Pai_pool_size
1. SQL Shared Buffer Pool
2. This parameter is the high-speed cache of the database and data dictionary.

Log_buffer 
1. Repeat the log Buffer

Sort_area_size 
1. sorting area

Processes
1. Number of processes simultaneously connected

Global_names 
1. If the "Database Link name" has the same name as the "Database" to be connected to, set global_names = true. Otherwise, set global_names = false.

Db_block_size 
1. Database block size
2. The default Oracle block is 2 kb, which is too small, because if we have an 8 KB data, the 2 kb database needs to read the disk four times before reading it, i/O operations are greatly reduced as long as the 8 KB database is read once.
3. After the database is installed, you can no longer change the value of db_block_size. You can only create a new database. When creating a database, you must manually install the database.

Open_links 
1. Number of simultaneously opened links
 
Dml_locks 
1. You can set the maximum number of locks for a table at a time.
2. If three users modify six tables, 18 DML locks are required for parallel operations. If the value of dml_locks is not large enough, the operation will be interrupted, you can estimate the value of dml_locks required by the system based on the operation scale of your application and the maximum number of concurrent users. However, the value does not affect other database performance, therefore, it is usually set to a large value, far greater than the actual possible value. If the table is often locked during system operation, you should consider increasing the value.

Open_cursors 
1. Number of opened cursors
2. This parameter can be owned by each user process at the same time. The maximum value of this parameter varies with the operating system.
3. When creating a compositing view that contains many tables, if this parameter is small, the view creation will fail.

Dbwr_io_slaves 
1. Number of background write Processes