Patent ID: 7657584
Filing Date: 2010-02-02
Classification: G06F

Abstract:
1. A reorganization method of a database stored in a disk drive controlled by a computer, the disk drive comprising: a first volume that stores the database; and a second volume that forms a pair with the first volume to store a replication of the database, the method comprising the steps of: acquiescing a transaction of the database by the computer; splitting the pair formed of the first volume and the second volume, and making settings to allow an access only to the database stored in the first volume; releasing the transaction from the quiescent state; specifying a sparse space in the database in the second volume, wherein the database in the second volume includes sparse space areas and dense space areas, by selecting from the database in the second volume a leaf block having high discontinuity caused with a plurality of the sparse space areas and dense space areas; partially reorganizing only the specified sparse space in the second volume and not reorganizing the dense space in the second volume, the reorganizing being executed by storing the same data block of the database in physically continuous areas; and copying the contents of the partially reorganized second volume to the first volume such that the first volume and the second volume are resynchronized and form the pair again, wherein the step of specifying the sparse space distinguishes the sparse space from the dense space in the database in the second volume and includes the step of determining whether the sparse space will be identified by whether a filling rate of unit areas of the second volume is equal to or less than a predetermined threshold or identified by the I/O cost of reading and writing data from and to leaf blocks of the second volume, wherein, if it is determined that the step of specifying the sparse space will be identified by the I/O cost, the step of specifying the sparse space further comprises the steps of: calculating a value indicating discontinuity for each unit area to be reconfigured as to an index area in the database; and specifying the unit area as a target area of partial reorganization when the value indicating the discontinuity exceeds a predetermined rate, the step of calculating the value indicating the discontinuity calculates a value that indicates a distance between physical locations of adjacent key values on the second volume among key values comprising a reorganization unit area in the index area, the step of specifying the unit area as the target area of the partial reorganization specifies the unit area as a target area of partial reorganization when the distance exceeds a predetermined threshold value, and if it is determined that the step of specifying the sparse space will be identified by the filling rate of the unit areas of the second volume, the step of specifying sparse space further comprises the steps of: determining whether or not the filling rate of each unit area in the second volume is equal to or smaller than the predetermined threshold; and if the filling rate of a unit area is less than or equal to the predetermined threshold, adding the unit area to a target extent list to be partially reorganized.