Cov txheej txheem:
Video: Dab tsi yog snapshot qub yuam kev?
2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47
ORA-01555 yuam kev Lus “ Snapshot dhau lawm ” yuam kev ORA-01555 muaj cov lus, snapshot qub dhau lawm ” Cov lus no tshwm sim los ntawm Oracle nyeem cov txheej txheem sib xws. Thaum koj cov lus nug pib khiav, cov ntaub ntawv yuav raug hloov ib txhij los ntawm lwm tus neeg siv cov ntaub ntawv.
Ib yam li ntawd, dab tsi yog undo retention?
Thaum tsis siv neeg thim rov qab kev tswj yog enabled, muaj ib txwm muaj tam sim no undo tuav tseg lub sijhawm, uas yog lub sijhawm tsawg kawg nkaus uas Oracle Database sim khaws cov qub thim rov qab cov ntaub ntawv ua ntej overwriting nws. Laus (cog lus) thim rov qab cov ntaub ntawv uas laus dua li tam sim no undo tuav tseg lub sijhawm tau hais tias yuav tas sijhawm.
Ib tug kuj yuav nug, dab tsi yog kev tuav pov hwm hauv Oracle? Kev tuav pov hwm : Ua lav kev vam meej ntawm cov lus nug ntev los yog oracle flashback kev ua haujlwm, koj tuaj yeem pab tau kev tuav pov hwm.
Tsuas yog li ntawd, koj yuav ua li cas kom tshem tawm kev tuav pov hwm?
Txhawm rau teem sijhawm undo tuav tseg:
- Teem undo_retention hauv cov ntaub ntawv pib parameter.
- Undo_retention = 1800.
- Hloov undo_retention txhua lub sijhawm uas siv cov lus hloov kho:
- Hloov system teeb undo_retention = 2400;
Oracle rollback ntu yog dab tsi?
A Rollback Segment yog ib qho khoom siv database uas muaj ua ntej-duab ntawm cov ntaub ntawv sau rau hauv database. Rollback ntu yog siv los: Undo hloov thaum muaj kev hloov pauv rov qab. Xyuas kom meej tias lwm yam kev lag luam tsis pom kev hloov pauv tsis tau ua rau hauv cov ntaub ntawv.
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