Oracle 参数 DB_BLOCK_BUFFERS 官方解释，作用，如何配置最优化建议
本站中文解释
：
DB_BLOCK_BUFFERS参数用于控制数据库缓存中存储数据块和索引加载到SGA的替代物理内存部分的大小。它的取值范围是0-64G，并且默认值为DB_CACHE_SIZE的50%-75%。
正确设置DB_BLOCK_BUFFERS参数，可以提高数据库性能：
1、在系统上运行数据库分析工具，比如V$ tablespace, V$ db_block_buffers等，以确定当前的内存状态。
2、根据数据库分析的结果，调整DB_BLOCK_BUFFERS参数的大小，使之达到最优，使得内存中有足够的缓存块，而不会导致太多的IO等待。
3、不要将DB_BLOCK_BUFFERS参数设置过大，以免有效系统内存消耗殆尽，导致内存不足，系统抛出内存不足错误。
官方英文解释
DB_BLOCK_BUFFERS specifies the number of database buffers in the buffer cache.
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
|
|
Modifiable |
No |
|
Modifiable in a PDB |
No |
|
Range of values |
|
|
Basic |
No |
|
Oracle RAC |
Multiple instances can have different values, and you can change the values as needed. |
Note:
DB_BLOCK_BUFFERS cannot be combined with the dynamic DB_CACHE_SIZE parameter; combining these parameters in the same parameter file will produce an error.
DB_BLOCK_BUFFERS is one of several parameters that contribute to the total memory requirements of the SGA of an instance.
This parameter, together with DB_BLOCK_SIZE, determines the total size of the buffer cache. Effective use of the buffer cache can greatly reduce the I/O load on the database. DB_BLOCK_SIZE can be specified only when the database is first created, so you use DB_BLOCK_BUFFERS to control the size of the buffer cache.
Note:
The DB_BLOCK_BUFFERS initialization parameter is deprecated. It is maintained for backward compatibility.
Oracle recommends that you use DB_CACHE_SIZE instead.
See Also:
“DB_CACHE_SIZE”
