مقاله انگلیسی رایگان در مورد بازسازی بلاک چین با پایگاه داده های توزیع شده – الزویر 2019

A blockchain is a decentralised linked data structure that is characterised by its inherent resistance to data modification, but it is deficient in search queries primarily due to its inferior data formatting. A distributed database is also a decentralised data structure which features quick query processing and well-designed data formatting but suffers from data reliability. In this work, we showcase ChainSQL, an open-source system developed by integrating the blockchain with the database, i.e. we present a blockchain database application platform that has the decentralised, distributed and audibility features of the blockchain and quick query processing and well-designed data structure of the distributed databases. ChainSQL features a tamper-resistant and consistent multi-active database, a reliable and cost effective data-level disaster recovery backup and an auditable transaction log mechanism. The system is presented as an operational multi-active database along with the data-level disaster recovery backup and audibility features. A comprehensive experimental evaluation is performed to demonstrate the effectiveness of the system.

Introduction

Digital or crypto currencies such as, Bitcoin [1], Ethereum [2], Ripple [3] and others, have recently witnessed a tremendous interest from the user as well as the developer community [4, 5, 6]. The crypto currencies are essentially smart contracts between users which are executed using a data structure referred to as ‘blockchain’. Thus, a blockchain stores transactions whilst satisfying the following two constraints: (i) anyone should be able to write to the blockchain, and (ii) there should not be any centralised control. A blockchain is a database and an application software on top of it [7] that dictates the data definition and data update mechanism for the blockchain. A blockchain not only allows to add new data to the database but it also ensures that all the users on the network have exactly the same data. Thus, a blockchain is a distributed and decentralised linked data structure for data storage and retrieval which also ensures that the data is resistant to any modification. One of the limitations of blockchain is its inherent deficiency in search query processing [8] primarily due to the linked data storage and the absence of a well-defined data indexing structure for various queries. Bitcoin, for instance, is the most notable blockchain network; however, it has two limitations: (i) it takes a considerable amount of time, possibly up to ten minutes, for a transaction to be issued and verified and the final confirmation may take up to an hour, and (ii) a new block can only be generated by miners which requires extensive computational efforts. Databases, in addition to having a defined data structure are optimised for fast query processing, but are not resistant to data modifications [9]. More specifically, distributed databases have the following limitations: (a) database can be tampered either by a malicious user or by the database administrator, (b) the backup-based disaster recovery scheme of the database cannot be normally activated in the event of a system failure and causes data loss, and (c) the multiple copies of the database are not always entirely consistent and the data synchronisation operations are required to resolve data conflicts. Therefore, a blockchain-based database system is desirable that has the features of the blockchain and the distributed databases combined together such that the inherent resistance of the blockchain to data modification and the query speed of the distributed databases are simultaneously achieved.