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What is deadlock and How can it occur in a distributed database systam?
Wiki User
∙ 13y ago
It is when two processes are waiting for something and unable to continue. For example, if you have process A which needs a lock on database X and Y but only has a lock on database X while there is a process B which needs the same locks but only has a lock on database Y, then the 2 processes could potentially wait forever if they are unwilling to let go of their existing locks.
Wiki User
∙ 13y ago
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What is false deadlock?
the coordinator conculde incorrectly that a deadlock exist and kills some process --------------------------- Detecting a non existent deadlock in distributed system has been referred as false deadlock and it may occur due to communication delay.. ---->Ashok Paranjothi
What is centralized database?
Distributed and Centralized Databases Distributed data is defined as collection of logically distributed database which are connected with each other through a network. A distributed database management system is used for managing distributed database. Each side has its own database and operating system.A centralized database has all its data on one place. As it is totally different from distributed database which has data on different places. In centralized database as all the data reside on one place so problem of bottle-neck can occur, and data availability is not efficient as in distributed database. Let me define some advantages of distributed database, it will clear the difference between centralized and distributed database.Users can issue commands from any location to access data and it does not affect the working of database. Distributed database allows us to store one copy of data at different locations. Its advantage is that if a user wants to access data then the nearest site (location) will provide data so it takes less time.There are multiple sites (computers) in a distributed database so if one site fails then system will not be useless, because other sites can do their job because as I earlier said that same copy of data is installed on every location. You will not find this thing in centralized database.Any time new nodes (computers) can be added to the network without any difficulty.Users do not know about the physical storage of data and it is known as distribution transparency, as we know that ideally, a DBMS must not show the details of where each file is stored or we can say that a DBMS should be distribution transparent.
What problems could occur if a student database is not maintained?
What problem can occur if a student database is not maintained
What is the difference among deadlock avoidance detection and prevention?
Deadlock avoidance involves ensuring that the system never enters a deadlock state by using techniques like resource allocation strategies (e.g., Banker's algorithm) to ensure that resources are allocated in a way that avoids deadlock. Deadlock detection, on the other hand, involves periodically checking the system to see if a deadlock has occurred after it has happened. Deadlock prevention focuses on designing algorithms and protocols in a way that eliminates one of the conditions necessary for deadlock to occur, such as by ensuring that resources are requested in a specific order.
Is it possible to occur deadlock in one process during rsource allocation?
No. This follows directly from the hold-and-wait condition. Raj Gopal Mishra (India)
What is necessary condition for deadlock to occur?
1. Competition for non-sharable resources2. Resources requested on a partial basis3. An allocated resource can not be forcibly retrieved
What is the prime attribute in a database?
It is an attribute that does not occur in some candidate key.
What is the purposed normalization in database?
The purpose of normalization is to reduce the chances for anomalies to occur in a database. The Normalization also forces you to use a database in a Object orientated manner. (This is good of course.)
How many types of database connectivity occur?
How many types of database connectivity occur? answer: well,There are several types of database 5 kinds considered to be under database types and 4 under the classification by location: n-1 Single- user:supports only one user at a time .-2 desktop:single=usere database running on a personal computer.3-Multi-user:supports multiple users at the same time such tat can be said as "network"where there are more than one computer at a time.4- workgroupMulti-user database that supports a small group of users or a single department.5-Enterprise;Multi-user database that supports a large group of users or an entire organizationNow is the classification by location database types:1-centralized:supports data located at a single site.2-Distributed :suporrts data distributed across several sites.3-Transactional(or production):supports a company's day to day operations.4-data warehouse:stores data used to generate information required to make tactical or strategic decisions.however,often used to store historical data as well as the structure database is quite different.thanks for reading the artical.MY name is serag zentani if there is any inquire plz do contact me legend1977z@hotmail.com
What are the differences between deadlock avoidance and deadlock prevention in operating systems?
Deadlock Prevention: o Preventing deadlocks by constraining how requests for resources can be made in the system and how they are handled (system design). o The goal is to ensure that at least one of the necessary conditions for deadlock can never hold. * Deadlock Avoidance: o The system dynamically considers every request and decides whether it is safe to grant it at this point, o The system requires additional apriori information regarding the overall potential use of each resource for each process. o Allows more concurrency. Similar to the difference between a traffic light and a police officer directing traffic. * Deadlock deduction:- Often, neither avoidance nor deadlock prevention may be used. Instead deadlock detection and process restart are used by employing an algorithm that tracks resource allocation and process states, and rolls back and restarts one or more of the processes in order to remove the deadlock. Detecting a deadlock that has already occurred is easily possible since the resources that each process has locked and/or currently requested are known to the resource scheduler or OS. Detecting the possibility of a deadlock before it occurs is much more difficult and is, in fact, generally undecidable, because the halting problem can be rephrased as a deadlock scenario. However, in specific environments, using specific means of locking resources, deadlock detection may be decidable. In the general case, it is not possible to distinguish between algorithms that are merely waiting for a very unlikely set of circumstances to occur and algorithms that will never finish because of deadlock. Deadlock detection techniques include, but is not limited to, Model checking. This approach constructs a Finite State-model on which it performs a progress analysis and finds all possible terminal sets in the model. These then each represent a deadlock.
What is dependencies in database?
Referentail dependencies occur when an object is referenced in the definition of another object
Discuss various errors that occur during database design. explain various database integrity issues in detail.?
i am not aware about it.if u get to know then let me know
