oracle back log,11g闪回日志(flashback log)保留时间参数 - db_flashback_retention_target
查看? DB_FLASHBACK_RETENTION_TARGET 參數(shù)是默認(rèn)值 1440 (分鐘), 即一天時(shí)間。 文檔對(duì)于它的解釋如下:
DB_FLASHBACK_RETENTION_TARGET specifies the upper limit (in minutes) on how far back in time the database may be flashed back. How far back one can flashback a database depends on how much flashback data Oracle has kept in the flash recovery area.
但是實(shí)際測(cè)試中發(fā)現(xiàn), 只要 flashback 區(qū)足夠大,歸檔文件不刪除,系統(tǒng)都可以回退到超過1天的某個(gè)歷史時(shí)間點(diǎn), 沒有對(duì)閃回日志
文件進(jìn)行覆蓋 。
版主 : 我覺得這個(gè)和control_file_record_keep_time樣,只是代表了一天前的flashback log可以被刪除,但是否刪除,還是看fra使用率是否達(dá)到那個(gè)閾值。
作者的話: 這里的閥值應(yīng)該指的是 參數(shù) db_recovery_file_dest_size 設(shè)置的大小 ,這個(gè)大小只是一個(gè)閥值,不會(huì)占用空間。
版主Yong Huang:
I searched on MOS but couldn't find an answer. Zergduan's explanation may be right.
I remember we used to enable flashback database on our 10gR2 database. It quickly ran out of space and, contrary to what we learned, the logs were not automatically deleted. I don't think we set any guaranteed restore point, and the DB_FLASHBACK_RETENTION_TARGET setting was not outrageous. We stopped doing it anyway.
詳情參考 :? http://www.itpub.net/thread-1864839-1-1.html
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