Sep 13, · Distributed Database MCQ with Answers. Distributed Database MCQ with Answers – important Distributed Database MCQs are here for the students to qualify for various academic and competitive exams.. Which of the following is true concerning a global transaction? a. The required data are at one local site and the distributed DBMS routes request as necessary Suppose I have two database servers (DB-SERVER-1 & DB-SERVER-2), and there is a single database on each server (DB1 & DB2). Both are SQL Server databases. Is Making reliable distributed systems in the presence of software errors, [Free] Joe Amstrong's (Author of Erlang) PhD thesis Designing Data Intensive Applications [Amazon Link] Distributed Machine Learning Patterns, Yuan Tang, Practical patterns for scaling machine learning from your laptop to a distributed cluster
GitHub - theanalyst/awesome-distributed-systems: A curated list to learn about distributed systems
Distributed computing is a field of computer science that studies distributed systems. A distributed system is a system whose components are located on different networked computerswhich communicate and coordinate their actions by passing messages to one another from any system. Three significant characteristics of distributed systems are: concurrency of components, distributed databases thesis, lack of a global clockand independent failure of components.
A computer program that runs within a distributed system is called a distributed program and distributed programming is the process of writing such programs.
Distributed computing also refers to the use of distributed systems to solve computational problems. In distributed computinga problem is divided into many tasks, each of which is solved by one or more computers, [4] which communicate with each other via message passing. The word distributed in terms such as "distributed system", "distributed programming", and " distributed algorithm " originally referred to computer networks where individual computers were physically distributed within some geographical area, distributed databases thesis.
While there is no single definition of a distributed system, [7] the following defining properties are commonly used as:. A distributed system may have a common goal, such as solving a large computational problem; [10] the user then perceives the collection of autonomous processors as a unit. Alternatively, each computer may have its own user with individual needs, and the purpose of the distributed system is to coordinate the use of shared resources or provide communication services to the users.
Distributed systems are groups of networked computers which share a common goal for their work. The terms " concurrent computing ", " parallel computing ", and "distributed computing" have much overlap, and no clear distributed databases thesis exists between distributed databases thesis. The figure on the right illustrates the difference between distributed and parallel systems.
Figure a is a schematic view of a typical distributed system; the system is represented as a network topology in which each node is a computer and each line connecting the nodes is a communication link. Figure b shows the same distributed system in more detail: each computer has its own local memory, distributed databases thesis, and information can be exchanged only by passing messages from one node to another by using the available communication links, distributed databases thesis.
Figure c shows a parallel system in which each processor has a direct access to a shared memory. The situation distributed databases thesis further complicated by the traditional uses of the terms parallel and distributed algorithm that do not quite match the above definitions of parallel and distributed systems see below for more detailed discussion.
Nevertheless, as a rule of thumb, high-performance parallel computation in a shared-memory multiprocessor uses parallel algorithms while the coordination of a large-scale distributed system uses distributed algorithms.
The use of concurrent processes which communicate through message-passing has its roots in operating system architectures studied in the s. ARPANETone of the predecessors of the Internetwas introduced in the late s, and ARPANET e-mail was invented in the early s. E-mail became the most successful application of ARPANET, [23] and it is probably the earliest example of a large-scale distributed application. In addition to ARPANET and its successor, the distributed databases thesis Internetother early worldwide computer networks included Usenet and FidoNet from the s, both of which were used to support distributed discussion systems.
The study of distributed computing became its own branch of computer science in the late s and early s. The first conference in the field, Symposium on Principles of Distributed Computing PODCdates back toand its counterpart International Symposium on Distributed Computing DISC was first held in Ottawa in as the International Workshop on Distributed Algorithms on Graphs. Various hardware and software architectures are used for distributed databases thesis computing.
At a lower level, it is necessary to interconnect multiple CPUs with distributed databases thesis sort of network, regardless of whether that network is printed onto a circuit board or made up of loosely coupled devices and cables. At a higher distributed databases thesis, it is necessary to interconnect processes running on those CPUs with some sort of communication system. Distributed programming typically falls into one of several basic architectures: client—serverthree-tiern -tieror peer-to-peer ; or categories: loose couplingor tight coupling, distributed databases thesis.
Another basic aspect of distributed computing architecture is the method of communicating and coordinating work among concurrent processes. Alternatively, a "database-centric" architecture can enable distributed computing to be done without any form of direct inter-process communicationby utilizing a shared database. This enables distributed computing functions both within and beyond the parameters of a networked database.
Examples of distributed systems and applications of distributed computing include the following: [33]. Many tasks that we would like to automate by using a computer are of question—answer type: we would like to ask a question and the computer should produce an answer. In theoretical computer sciencesuch tasks are called computational problems.
Formally, a computational problem consists of instances together with a solution for each instance. Instances are questions that we can ask, and solutions are desired answers to these questions. Theoretical computer science seeks to understand which computational problems can be solved by using a computer computability theory and how efficiently computational complexity theory. Traditionally, it is said that a problem can be solved by using a computer if we can design an algorithm that produces a correct solution for any given instance.
Such an algorithm can be implemented as a computer program that runs on a general-purpose computer: the program reads a problem instance from inputperforms some computation, and produces the solution as output, distributed databases thesis.
Formalisms such as random-access machines or universal Turing machines can be used as abstract models of a sequential general-purpose computer executing such an algorithm, distributed databases thesis. The field of concurrent and distributed computing studies similar questions in the case of either multiple distributed databases thesis, or a computer that executes a network of interacting processes: which computational problems can be solved in such a network and how efficiently?
However, it is not at all obvious what is meant by "solving a problem" in the case of a concurrent or distributed system: for example, what is the task of the algorithm designer, and what is the concurrent or distributed equivalent of a sequential general-purpose computer?
The discussion below focuses on the case of multiple computers, although many of the issues are the same for concurrent processes running on a single computer. In the case of distributed algorithms, computational problems are typically related to graphs. Often the graph that describes the structure of the computer network is the problem instance.
This is illustrated in the following distributed databases thesis. Consider the computational problem of finding a coloring of a given graph G. Different fields might take the following approaches:. While the field of parallel algorithms has a different focus than the field of distributed algorithms, there is much interaction between the two fields.
For example, the Cole—Vishkin algorithm for graph coloring [41] was originally presented as a parallel algorithm, but the same technique can also distributed databases thesis used directly distributed databases thesis a distributed algorithm.
Moreover, a parallel algorithm can be implemented either in a parallel system using shared memory or in a distributed system using message passing. run in any given distributed databases thesis does not lie in the same place as the boundary between parallel and distributed systems shared memory vs. message passing.
In parallel algorithms, yet another resource in addition to time and space is the number of computers. Indeed, often there is a trade-off between the running time and the number of computers: the problem can be solved faster if there are more computers running in parallel see speedup.
Distributed databases thesis a decision problem can be solved in polylogarithmic time by using a polynomial number of processors, distributed databases thesis, then the problem is said to be in the class NC. In the analysis of distributed algorithms, distributed databases thesis, more distributed databases thesis is usually paid on communication distributed databases thesis than computational steps, distributed databases thesis.
Perhaps the simplest model of distributed computing is a synchronous system where all nodes operate in a lockstep fashion. This model is commonly known as the LOCAL model.
During each communication distributed databases thesisdistributed databases thesis, all distributed databases thesis in parallel 1 receive the latest messages from their neighbours, 2 perform arbitrary local computation, and 3 send new messages to their neighbors. In such systems, a central complexity measure is the number of synchronous communication rounds required to complete the task.
This complexity measure is closely related to the diameter of the network. Let D be the diameter of the network. On the one hand, any computable problem can be solved trivially in a synchronous distributed system in approximately 2 D communication rounds: simply gather all information in one location D roundssolve the problem, distributed databases thesis, and inform each node about the solution D rounds.
On the other hand, if the running time of the algorithm is much smaller than D communication rounds, then the nodes in the network must produce their output without having the possibility to obtain information about distant parts of the network.
In other words, the nodes must make globally consistent decisions based on information that is available in their local D-neighbourhood. Many distributed algorithms are known with the running time much smaller than D rounds, distributed databases thesis, and understanding which problems can be solved by such algorithms is one of the central research questions of the field.
Another commonly used measure is the total number of bits transmitted in the network cf, distributed databases thesis. communication complexity. Traditional computational problems take the perspective that the user asks a question, a computer or a distributed system processes the question, then produces an answer and stops. However, there are also problems where the system is required not to stop, distributed databases thesis, including the dining philosophers problem and other similar mutual exclusion problems.
In these problems, the distributed system is supposed to continuously coordinate the use of shared resources so that no conflicts distributed databases thesis deadlocks distributed databases thesis. There are also fundamental challenges that are unique to distributed computing, for example those related to fault-tolerance.
Examples of related problems include consensus problems[48] Byzantine fault tolerance[49] and self-stabilisation. Much research is also focused on understanding the asynchronous nature of distributed systems:. Coordinator election or leader election is the process of designating a single process as the organizer of some task distributed among several computers nodes. Before the task is begun, all network nodes are either unaware which node will serve as the "coordinator" or leader of the task, or unable to communicate with the current coordinator.
After a coordinator election algorithm has been run, however, distributed databases thesis, each node throughout the network recognizes a particular, unique node as the task coordinator. The network nodes communicate among themselves in order to decide which of them will get into the "coordinator" state.
For that, they need some method in order to break the symmetry among them, distributed databases thesis. For example, if each node has unique and comparable identities, then the nodes can compare their identities, and decide that the node with the highest identity is the coordinator.
The definition of this problem is often attributed to LeLann, who formalized it as a method to create a new token in a token ring network in which the token has been lost. Coordinator election algorithms are designed to be economical in terms of total bytes transmitted, and time.
The algorithm suggested by Gallager, Humblet, and Spira [56] for general undirected graphs has had a strong impact on the design of distributed algorithms in general, and won the Dijkstra Prize for an influential paper in distributed computing, distributed databases thesis.
Many other algorithms were suggested for different kind of network graphssuch as undirected rings, unidirectional rings, complete graphs, distributed databases thesis, grids, directed Euler graphs, and others. A general method that decouples the issue of the graph family from the design of the coordinator election algorithm was suggested by Korach, Kutten, and Moran. In order to perform coordination, distributed systems employ the concept of coordinators.
The coordinator election problem is to choose a process from among a group of processes on different processors in a distributed system to act as the central coordinator. Several central coordinator election algorithms exist. So far the focus has been on designing a distributed system that solves a given problem.
A complementary research problem is studying the properties of a given distributed system. The halting problem is an analogous example from the field of centralised computation: we are given a computer program and the task is to decide whether it halts or runs forever. The halting problem is undecidable in the general case, and naturally understanding the behaviour of a computer network is at least as hard as understanding the behaviour of one computer, distributed databases thesis.
However, there are many interesting special cases that are decidable. In particular, it is possible to reason about the behaviour of a network of finite-state machines.
One example is telling whether a given network of interacting asynchronous and non-deterministic finite-state machines can reach a deadlock.
This problem is PSPACE-complete[62] i. From Wikipedia, the free encyclopedia. System whose components are located on different networked computers.
24 - Distributed OLAP Databases (CMU Databases Systems / Fall 2019)
, time: 1:25:15Query two SQL Server databases on two different servers - Database Administrators Stack Exchange
Suppose I have two database servers (DB-SERVER-1 & DB-SERVER-2), and there is a single database on each server (DB1 & DB2). Both are SQL Server databases. Is Middleware in the context of distributed applications is software that provides services beyond those provided by the operating system to enable the various components of a distributed system to communicate and manage data. Middleware supports and simplifies complex distributed blogger.com includes web servers, application servers, messaging and similar Our thesis writers can help with researching, editing, and writing any type of academic assignment at any level. If you are just looking to have a custom list of engineering research topics, our experts can help create a list to fit any assignment requirements
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