今天发现有一个 oracle 物理DataGuard apply比较慢，根据官方dg 优化文档修改相关参数，

下面的方法有一点效果，不过不大。

1、修改并行度

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE PARALLEL 8 using current logfile disconnect from session;

2、修改消息大小

alter system Set PARALLEL_EXECUTION_MESSAGE_SIZE = 4096 scope=spfile;

3、取消block check

alter system set DB_BLOCK_CHECKSUM=false scope=spfile;

4、异步IO

alter system set disk_asynch_io=TRUE scope=spfile;

5、os异步传输

alter system set filesystemio_options=setall scope=spfile;

asynch:启用异步I/O

directio:启用同步I/O

setall:同时启用异步和同步I/O

none:禁用异步和同步I/O

(ALTER DATABASE RECOVER managed standby database cancel)