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The replication mechanism of NoSQL database MongoDB includes Master/Slave structure and Replica Set. Write operation implement on Master, Slaves will send the synchronize data command asynchronously to Master to update its data. Read operation just implement on Master to provide the strong consistency, while read operation implement on Slave to provide the eventual consistency. Replica set is a group...
MongoDB is one of the typical NoSQL database. The database mechanisms of MongoDB about document-oriented storage, GridFS for storing files of any size. The data storage structure of MongoDB is given, which uses BSON as the data storage and network transfer format for documents, simple and fast in query and easy in horizontal scalability with low cost.
In view of the actual situation which the oil pump daily operation management mainly depended on manual inspection, this paper presents an oil pump temperature monitoring system based on Internet of things by using ARM-S3C2410 chip and DS18B20 temperature sensor. By installing the DS18B20 sensors in front of and behind the oil pump motor bearings; this monitoring system can collect the real-time temperature...
Internet governance has been a controversial issue among governments, private sector and Internet users since the US government ended its restriction on Internet in the early 1990s. However, as there is still no academic consensus on its definition, the concept of Internet governance can be very broad, and it is difficult to identify authors' arguments from different perspectives. This literature...
A variety of on-line businesses are rapidly emerging over the Internet, which is believed to be one of the most efficient ways to provide all electronic services. An electronic and secure electronic cash (“e-cash” in short) system plays an important role to support these businesses safely as a trustful payment over the Internet. We describe the problems faced by previous e-cash system. Based on these...
The advanced technologies in the information age have instilled new energy to the experimental education. A new experimental education scheme for technical courses has been proposed, including education of experiment principles, Web-based presentation of experiment resources, preparation of experiments and its examination, virtual experiments and their examination, administration of open real experiments,...
This paper investigates a random edge deletion model for directed scale-free graphs that grow with preferential attachment depending on the in- and out-degrees, we show that the resulting in- and out-degree distributions are power laws with correlated exponents, reproducing observed properties of the World-Wide Web.
To deal with the problem of too many results returned from a Web database in response to a user query, this paper proposes a novel approach, which takes advantage of the contextual preferences to precompute a few representative orders of tuples and uses them to expeditiously provide ranked answers factoring in the information contained in the query. Contextual preferences take the form that item i...
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