In section 9.3.2 of "Principles of Computer System Design" LOG is a procedure to write a log atomically (with all-or-nothing semantic) to disk to implement write-ahead-log protocol. But the book does not discuss the details about implementation of LOG. I want to know in practice how the LOG procedure is implemented, such as Mysql, Oracle, etc.
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spockwang
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Terminate the log entry with a marker that indicates the entry is complete? – eggyal Dec 11 '13 at 17:17
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@eggyal How can you make sure the marker is in the valid state? It also must be written atomically, so beg the question. – spockwang Dec 11 '13 at 17:20
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Read it back to see if the marker is present? If it is, all is well; if it's not, the log entry is invalid and can be ignored/discarded. – eggyal Dec 11 '13 at 17:45