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write-ahead protocol (116)

原创 IT综合 作者:tsinglee 时间:2007-10-31 10:58:30 0 删除 编辑

Before DBWn can write a modified buffer, all redo records
associated with the changes to the buffer must be written to disk (the
write-ahead protocol). If DBWn finds that some redo records have not
been written, it signals LGWR to write the redo records to disk and
waits for LGWR to complete writing the redo log buffer before it can
write out the data buffers.

写优先协议
当DBWn写出modified buffer之前 , 日志记录中与buffer中相关的需要先写入磁盘 ,
如果DBWn发现有日志记录还没有写出 , 它将通知LGWR将这些日志写入磁盘

[@more@]

来自 “ ITPUB博客 ” ,链接:http://blog.itpub.net/10599713/viewspace-979914/,如需转载,请注明出处,否则将追究法律责任。

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