Data recovering method and device

Abstract

The invention discloses a data recovering method and device, which can solve the problem that the performance of a database is low as a data file is frequently read from a magnetic disk in a database recovering process, and the problem that a database recovering speed is slow as continuous logs correspond to discontinuous data pages. The method comprises the following steps: obtaining at least one log from a recovering starting point in a log file; generating a virtual data page according to each Redo log in the at least one log, wherein the virtual data page is used for representing a data page obtained by redoing according to the Redo logs; and combining each virtual data page with a corresponding original data page to be recovered in the magnetic disk according to a storage sequence of the original data page to be recovered to obtain the recovered original data page. The data recovering method and device disclosed by the invention are mainly applied to the database recovering process.

Description

technical field [0001] The invention relates to the technical field of data processing, in particular to a data recovery method and device. Background technique [0002] At present, the database has been widely used. During the operation of the database, the database may be shut down unexpectedly due to unexpected reasons such as power outages and crashes. At this time, the database needs to be restored. [0003] In the prior art, when an operation is performed on a data file of a database, the operation is recorded to form a log and stored in the log file. Log files are stored on disk together with data files (data pages). The modification of the data file according to the operation instruction is performed in the memory. After the memory processes the data page according to the operation instruction, a dirty page will be generated. The dirty page is a data page that has been modified but not yet stored in the disk. The operation of storing the log file to the disk is pri...

AI Technical Summary

Problems solved by technology

[0004] In the process of realizing the above-mentioned data recovery, the inventor finds that there are at least the following problems in the prior art: according to the log, the data files in the disk need to be accessed once for the data pages involved in the log file. The number of reads and writes of the disk, and then occupy part or all of the disk input and output (Input / Output, referred to as I / O) resources

When the database is running normally, if the database operation involves reading data from the disk, its speed will be low due to the shortage of disk I / O resources, that is, the problem of low database performance.

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