关于设置log buffer 合理大小的几个要点

关于设置log buffer 合理大小的几个要点

1，缺省大小 MAX(0.5M, (128K * number of cpus))

2，On most systems, sizing the log buffer larger than 1M does not provide any
performance benefit.It merely uses extra memory.

3，查看'redo buffer allocation retries' 统计信息

SELECT NAME, VALUE
FROM V$SYSSTAT
WHERE NAME = 'redo buffer allocation retries';

The value of redo buffer allocation retries should be near zero over an interval. 如果相差太大，则需要设设置 log_buffer 大小了

4，log buffer space wait even 如果这个等待事件是主要的event 之一，说明log buffer 大小需要考虑下调整下大小了

----log_buffer 参数的修改需要重启服务器才能生效

show parameter log_buffer

alter system set log_buffer=xxx scope=spfile；