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本帖最后由 jackson198574 于 2014-04-16 09:32 编辑
回复 3# 蓦然princes
官方文档Concept:
checkpoint
1. A data structure that marks the checkpoint position, which is the SCN in the redo
thread where instance recovery must begin. Checkpoints are recorded in the control
file and each data file header, and are a crucial element of recovery.
2. The writing of dirty data blocks in the database buffer cache to disk. The database
writer (DBWn)process writes blocks to disk to synchronize the buffer cache with the
data files.
Checkpoint Process (CKPT)
The checkpoint process (CKPT)updates the control file and data file headers with
checkpoint information and signals DBWnto write blocks to disk. Checkpoint
information includes the checkpoint position, SCN, location in online redo log to begin
recovery, and so on. As shown in Figure 15–4, CKPT does not write data blocks to data
files or redo blocks to online redo log files.
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