Interested to Buy Any Domain ? << Click Here >> for more details...
How do you handle data concurrency in .NET ?
- 9 Answers
- 21612 Views
- Infogain, SunGard, I also Faced
- E-Mail Answers
Answer Posted / ravikumar
When multiple users attempt to modify data at the same
time, controls need to be established in order to prevent
one user's modifications from adversely affecting
modifications from simultaneous users. The system of
handling what happens in this situation is called
concurrency control.
Types of Concurrency Control
In general, there are three common ways to manage
concurrency in a database:
Pessimistic concurrency control: A row is unavailable to
users from the time the record is fetched until it is
updated in the database.
Optimistic concurrency control: A row is unavailable to
other users only while the data is actually being updated.
The update examines the row in the database and determines
whether any changes have been made. Attempting to update a
record that has already been changed results in a
concurrency violation.
"Last in wins": A row is unavailable to other users only
while the data is actually being updated. However, no
effort is made to compare updates against the original
record; the record is simply written out, potentially
overwriting any changes made by other users since you last
refreshed the records.
Pessimistic Concurrency
Pessimistic concurrency is typically used for two reasons.
First, in some situations there is high contention for the
same records. The cost of placing locks on the data is less
than the cost of rolling back changes when concurrency
conflicts occur.
Pessimistic concurrency is also useful for situations where
it is detrimental for the record to change during the
course of a transaction. A good example is an inventory
application. Consider a company representative checking
inventory for a potential customer. You typically want to
lock the record until an order is generated, which would
generally flag the item with a status of ordered and remove
it from available inventory. If no order is generated, the
lock would be released so that other users checking
inventory get an accurate count of available inventory.
However, pessimistic concurrency control is not possible in
a disconnected architecture. Connections are open only long
enough to read the data or to update it, so locks cannot be
sustained for long periods. Moreover, an application that
holds onto locks for long periods is not scalable.
| Is This Answer Correct ? | 12 Yes | 0 No |
Post New Answer View All Answers
What is the meaning of executenonquery?
What is the usage of the dataset object in ado.net?
Describe connection object in ado.net
What is data view and variable view?
Is datareader faster than datatable?
What is the role of data provider in ado.net?
What are the advantages and disadvantages of using datalist?
How can you add or remove rows from the datatable object of dataset?
What is a sqldataadapter?
Explain the dataadapter class in ado.net?
Explain the difference in record set and dataset?
What is sqldatasource?
What is ado full form?
Which components of a data provider is used to retrieve, insert, delete, or modify data in a data source?
What are ado.net objects?
