Patent ID: 7801855
Filing Date: 2010-09-21
Classification: G06F

Abstract:
1. A method of logging performed in a logging apparatus in a database management system (DBMS), the method comprising: generating a copied image of a data page being updated, the copied image being identical to an original image of the data page before being updated, wherein the copied image is temporarily stored in a first memory of the logging apparatus until a log record is generated; generating a log entry on the data page being updated, wherein the log entry is maintained in a second memory of the logging apparatus and not written in a log page; merging the generated log entry and another log entry to generate a merged log entry; performing an update operation with respect to the original image of the data page; and when the update operation is completed, generating the log record based on the original image, the copied image, and the merged log entry, and recording the log record in the log page, wherein the merging comprises: determining whether there exist one or more previously generated log entries with respect to the same area as an area of the data page being updated and uniting the log entry to the one or more previously generated log entries; determining whether there exist one or more previously generated log entries with respect to an area neighboring an area of the data page being updated and changing an offset value included in the one or more previously generated log entries in relation to the neighboring area; and determining whether there exists a previously generated log entry with respect to an area overlapping an area of the data page being updated and changing an offset value included in the previously generated log entry in relation to the overlapping area.