A New Version Model for Object-oriented Databases

• Main Authors: Feng, Hwai-Bih, 馮懷碧
• Other Authors: Jea Kuen-Fang
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/97540462423863161790

碩士 === 國立中興大學 === 資訊科學學系 === 86 === Providing the functionality of object version is essential to object-orienteddatabase systems. In this study we propose a new object version model, whichenhances the existing version models and provides more operations for users to use the functionality conveniently. This version model uses a new representation scheme to avoid the waste of storage space for large objects.At the same time, it can process regular objects,large objects and compositeobjects efficiently. We have implemented the proposed version model in CTSS(Chao Ta Storage System), which is a storage system developed by the database laboratory of National Chao Tung University. From this implementation, we have verifiedthe feasibility of this version model. The model is designed as an independent module, which can be easily plugged into CTSS or other object storage systems with a minor modification of some of its module interfaces. To understand the advantages and disadvantages of our model over others, we review the characteristics of various version models and then compare these models with ours. Since large objects in our model are stored in version difference, a fair amount of space saving can be expected. We analyze the space saving for each different data update ratio, and observe that, if the updatedata size is about 30% of the original object version and there are 10 regionsupdated, then there is at least69.7% of space saving.On the other hand, when we retrieve a regular or evaluated object version by its OID, the retrieving time is identical that needed for a non-versionable object.