checkpoint是什么意思

checkpoint的意思时检查站；边防关卡。

例句：French soldiers squared off with a gunman at a road checkpoint .

翻译：在一个公路检查站法国士兵摆开架势，准备迎战一名持q者。

例句：Soldiers opened fire on a car which failed to stop at an army checkpoint .

翻译：士兵向那辆拒绝在军事检查站停车检查的汽车开了火。

扩展资料

checkpoint在计算机软件数据库中还有检查点的意思，表示一个数据库内部事件，这个事件激活以后会触发数据库写进程(DBWR)将数据缓冲(DATABUFFER CACHE)中的脏数据块写出到数据文件中。

checkpoint在数据库中的两个作用：

1、保证数据库的一致性，这是指将脏数据写入到硬盘，保证内存和硬盘上的数据是一样的

2、缩短实例恢复的时间，实例恢复要把实例异常关闭前没有写出到硬盘的脏数据通过日志进行恢复。如果脏块过多，实例恢复的时间也会很长，检查点的发生可以减少脏块的数量，从而提高实例恢复的时间。

参考资料：百度百科-checkpoint

CKPT is responsible for:

• Signaling DBWn at checkpoints

• Updating data file headers with

checkpoint information

• Updating control files with

checkpoint information

Background Processes and Recovery: Checkpoint (CKPT)

To understand instance recovery, you need to understand the functioning of certain background

processes.

Every three seconds (or more frequently), the CKPT process stores data in the control file to

document which modified data blocks DBWn has written from the SGA to disk. This is called a

“checkpoint.” The purpose of a checkpoint is to identify that place in the online redo log file

where instance recovery is to begin (which is called the “checkpoint position”).

In the event of a log switch, the CKPT process also writes this checkpoint information to the

headers of data files.

Checkpoints exist for the following reasons:

• To ensure that modified data blocks in memory are written to the disk regularly so that data

is not lost in case of a system or database failure

• To reduce the time required for instance recovery. Only the online redo log file entries

following the last checkpoint need to be processed for recovery.

• To ensure that all committed data has been written to data files during shutdown

The checkpoint information written by the CKPT process includes checkpoint position, system

change number, location in the online redo log file to begin recovery, information about logs,

and so on.

ORACLE CHECKPOINT的作用

checkpoint是一个数据库事件，它将已修改的数据从高速缓存刷新到磁盘，并更新控制文件和数据文件。

我们知道了checkpoint会刷新脏数据，但什么时候会发生checkpoint呢？以下几种情况会触发checkpoint。

1.当发生日志组切换的时候

2.当符合LOG_CHECKPOINT_TIMEOUT，LOG_CHECKPOINT_INTERVAL，fast_start_io_target,fast_start_mttr_target参数设置的时候

3.当运行ALTER SYSTEM SWITCH LOGFILE的时候

4.当运行ALTER SYSTEM CHECKPOINT的时候

5.当运行alter tablespace XXX begin backup，end backup的时候

6.当运行alter tablespace ,datafile offline的时候

你再好好看看文档吧

1、系统补丁没打完全，导致关于系统数据库在执行io *** 作时，写数据的时间较长，且占用率较高，导致数据库checkpoint时间较长。

2、informix的onconfig中的某些参数（如：buffer）配置不规范或者不符合现网需求，导致系统性能下降，不能发挥数据库的性能。

3、数据库系统未对某些大数据量表进行优化，导致执行checkpoint的时间较长。

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