Oracle 参数 DB_LOST_WRITE_PROTECT 官方解释，作用，如何配置最优化建议
本站中文解释
DB_LOST_WRITE_PROTECT 参数控制数据库是否会恢复未提交的更改，改参数可以让数据库对于未提交的更改做出正确的恢复处理。当参数值为 TYPICAL 时，Ａｒｃｈｉｖｅ ｌｏｇ日志上所记录的任何未提交的更改都会被恢复。当参数值为 NEVER 时，数据库不会进行任何恢复，而且任何未提交的更改都会丢失。
正确设置该参数的方式是：
1、首先要确定数据库期望的恢复操作，是希望恢复未提交的更改还是要舍弃所有未提交的更改；
2、根据期待恢复操作的要求，正确设置DB_LOST_WRITE_PROTECT参数，若希望恢复未提交的更改，则将参数设置为 TYPICAL；若希望舍弃未提交的操作，则将参数设置为 NEVER 。
官方英文解释
DB_LOST_WRITE_PROTECT enables or disables lost write detection.
| Property | Description |
|---|---|
|
Parameter type |
String |
|
Syntax |
|
|
Default value |
|
|
Modifiable |
|
|
Modifiable in a PDB |
No |
|
Basic |
No |
|
Oracle RAC |
In Oracle RAC instances, the parameter value is systemwide. |
A data block lost write occurs when an I/O subsystem acknowledges the completion of the block write, while in fact the write did not occur in the persistent storage.
When the parameter is set to TYPICAL on the primary database, the instance logs buffer cache reads for read/write tablespaces in the redo log, which is necessary for detection of lost writes.
When the parameter is set to FULL on the primary database, the instance logs reads for read-only tablespaces and read/write tablespaces.
When the parameter is set to TYPICAL or FULL on the standby database or on the primary database during media recovery, the instance performs lost write detection.
When the parameter is set to NONE on either the primary database or the standby database, no lost write detection functionality is enabled.
