NAME

CHECKPOINT - 強制一個事務(wù)日志檢查點

SYNOPSIS

CHECKPOINT

DESCRIPTION 描述

 預(yù)寫式日志（Write-Ahead Logging (WAL)）缺省時在事務(wù)日志中每隔一段時間放一個檢查點。 （要調(diào)整這個原子化的檢查點間隔，你可以參考運行時選項 checkpoint_segments  和 checkpoint_segments 。） CHECKPOINT 強迫在命令聲明時立即進行檢查， 而不是等到下一次調(diào)度時的檢查點。

 檢查點是一個事務(wù)日志訓練中的點，在該點，所有數(shù)據(jù)文件都被更新以反映日志中的信息。 所有數(shù)據(jù)文件都將被沖刷到磁盤。請參考 Chapter 25 ``Write-Ahead Logging'' 獲取更多有關(guān) WAL 系統(tǒng)的信息。

 只有超級用戶可以調(diào)用 CHECKPOINT。 該命令不是設(shè)計用于正常操作過程中的。  

COMPATIBILITY 兼容性

CHECKPOINT 命令是 PostgreSQL 語言的擴展。  

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NAME

CHECKPOINT - force a transaction log checkpoint

SYNOPSIS

CHECKPOINT

DESCRIPTION

Write-Ahead Logging (WAL) puts a checkpoint in the transaction log every so often. (To adjust the automatic checkpoint interval, see the run-time configuration options checkpoint_segments and checkpoint_timeout.) The CHECKPOINT command forces an immediate checkpoint when the command is issued, without waiting for a scheduled checkpoint.

A checkpoint is a point in the transaction log sequence at which all data files have been updated to reflect the information in the log. All data files will be flushed to disk. Refer to the the chapter called ``Write-Ahead Logging'' in the documentation for more information about the WAL system.

Only superusers may call CHECKPOINT. The command is not intended for use during normal operation.  

COMPATIBILITY

The CHECKPOINT command is a PostgreSQL language extension.