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Improved Write-ahead Logging Disclosure Number: IPCOM000061164D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09

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Lindsay, BG McPherson, JA Mohan, C [+details]


A method is described for improved write-ahead logging whereby efficient recovery can be achieved with a limited amount of increased logging during normal operation. The method comprises, in addition to write-ahead logging descriptions of data base modifications, the steps of (1) constantly monitoring the state of each buffer page with respect to its nonvolatile storage version; (2) periodically logging records of said states for all dirty pages; and (3) during restart, using the log of descriptions of data base modifications and the log of said record said states to determine whether modifications to a page need to be undone or redone.