Oracle 参数 TRANSACTIONS_PER_ROLLBACK_SEGMENT 官方解释，作用，如何配置最优化建议
本站中文解释
TRANSACTIONS_PER_ROLLBACK_SEGMENT指定每个回滚段的事务数，用于划分回滚段，即设置每个回滚段保存的最大事务数量。可以根据自身的服务特点、并发访问量和资源大小等进行设置。
正确设置TRANSACTIONS_PER_ROLLBACK_SEGMENT的方法：
1、先分析数据库系统的最大事务数量是多少。
2、根据系统事务数量量来计算出每个回滚段所需要保存的事务数量。一般来说每个回滚段可以保存的事务量不能超过数据库系统的最大数量。
3、设置TRANSACTIONS_PER_ROLLBACK_SEGMENT的参数值，可以使用alter system命令来完成。如：alter system set
transactions_per_rollback_segment=XXX scope=spfile;
4、修改完后重启数据库，以使参数生效。
官方英文解释
TRANSACTIONS_PER_ROLLBACK_SEGMENT specifies the number of concurrent transactions you expect each rollback segment to have to handle.
| Property | Description |
|---|---|
|
Parameter type |
Integer |
|
Default value |
|
|
Modifiable |
No |
|
Modifiable in a PDB |
No |
|
Range of values |
1 to operating system-dependent |
|
Basic |
No |
|
Oracle RAC |
Multiple instances can have different values. |
The minimum number of rollback segments acquired at startup is TRANSACTIONS divided by the value for this parameter. For example, if TRANSACTIONS is 101 and this parameter is 10, then the minimum number of rollback segments acquired would be the ratio 101/10, rounded up to 11.
You can acquire more rollback segments by naming them in the parameter ROLLBACK_SEGMENTS.
See Also:
Your operating system-specific Oracle documentation for the range of values for this parameter.
