What will happen if two person are updating the same record in a table at the same time?
Although it may seem like two users are updating the same row of data at the same time, the MySQL DBMS would prevent this from happening; instead one user’s update would go first and one would go second. The result would be that both updates would go through (just not at the same time).
How multiple users handle same data change in SQL Server?
A classic approach is as follows:
- add a boolean field , “locked” to each table.
- set this to false by default.
- when a user starts editing, you do this: lock the row (or the whole table if you can’t lock the row) check the flag on the row you want to edit. if the flag is true then.
What will happen if two users attempt to UPDATE the same record in a database?
If two clients fetched the same version of the same data, they could unwittingly overwrite each-other’s changes if they assumed that they were the only ones editing that data at that time.
How do you handle multiple users changing the same data?
Answers. You need to write SQL that prevents that. You can go fancy and create a que that syncs data or you can use concurrency that prevents record updating on records that have been modified by someone else in the same time that you were changing the same record.
How can we handle multiple users making transactions in database simultaneously?
Two Phase Locking Protocol also known as 2PL protocol is a method of concurrency control in DBMS that ensures serializability by applying a lock to the transaction data which blocks other transactions to access the same data simultaneously. Two Phase Locking protocol helps to eliminate the concurrency problem in DBMS.
When two different transactions are trying to update the same column on the same row within a database at the same time is called?
A lost update occurs when two different transactions are trying to update the same column on the same row within a database at the same time.
When more than one user is accessing same data at the same time then it is known as?
When developing multi-user systems it is important to consider the desired outcome when two or more users or services simultaneously try to access the same data.
How does SQL Server handle concurrent updates?
In optimistic concurrency control, users do not lock data when they read it. When a user updates data, the system checks to see if another user changed the data after it was read. If another user updated the data, an error is raised. Typically, the user receiving the error rolls back the transaction and starts over.
What is meant by concurrent update and give an example?
Provide an example as well. The concurrent update problem is something that can happen when multiple database sessions are permitted to update the same data at the same time – which is why it’s called the concurrent update problem. Whenever a database user connects to the database, a new session is created.
How do you handle concurrent updates?
Usually, there are two ways to manage concurrent updates on resources:
- Pessimistic concurrency control – This implies that the service locks the resource so that a client cannot updated it. …
- Optimistic concurrency control – This implies that a client first obtains a token for the update operation.
Which database is best for concurrency?
This means SQLite supports greater concurrency than most other embedded database management systems, but not as much as client/server RDBMSs like MySQL or PostgreSQL.
When two transactions are being processed against the database at the same time?
When two transactions are being processed against the database at the same time they are termed concurrent transactions.
How do Web applications handle multiple users?
User has registered and logged in to the site – so you need a table in your database to contain a list of users – and it would probably help if you had some unique ID in it to identify each user. You can then use ASP.NET session to keep track of which user is active in each session / whether logged in etc.