Know more about redo log buffer and latches
1.
The Total size of the log buffer is determined by LOG_BUFFER parameter.
2.
Only Server process may pin a data block in exclusive mode.
3.
LGWR writes to the redo log files when:
- The redo log buffer is 1/3 full.
- 1 MB of data have been written to the redo log buffer.
- A 3-second time-out occurs.
- commit!
- before dbwr write out dirty buffers
- A thread is closed
- Acquire the redo writing and redo allocation latches
- determine the buffer to write out
- Release the redo allocation latch
- determine how many writes are required
- Log file parallel write
- Log buffer space
- Log file sync
- REDO writes === Number of times the log buffer is written
- redo blocks written === Number of times the log buffer is written
- redo write time === Total time required to write all the redos to disk
- redo buffer allocation retires === Total number of retries necessary to allocate space in the redo buffer
posted on 2009-06-20 07:08 Oracle和MySQL 阅读(184) 评论(0) 编辑 收藏 举报