This is really the write threshhold. When this many blocks in the redo buffer are filled, lgwr will
initiate a write of the log buffer automatically (without getting a sync request). This defaults to one
initiate a write of the log buffer automatically (without getting a sync request). This defaults to one
third of the log buffer or 1Megabyte, whichever is less.
这个解释是从网上搜索到的,但是没有版本信息。还要继续研究下