What is concurrancy?

Answer 1

Concurrency, in computing, refers to when multiple path of execution (threads or processes) are running at the same time. This is a very loosely defined term and may refer to multiple things:

1. Multiple processes or threads executing on the same processor are said to be running concurrently.
2. Multiple processes or threads executing on different processors may be said to be "truly concurrent," since they can be running instructions at the same time (without the need of a CPU scheduler).
3. Even a CPU with a pipeline may be said to be executing several instructions concurrently.

Answer 2

Concurrency will allow simultaneous access of the same data, which can be accessed by different users.There are two different locks that can be applied:

Exclusive, while the user has access to the data, the row will become locked - allowing the user to insert, update or delete records. This ensures that the data can only be modified by one user at a time, avoiding multiple changes.

Shared Lock, users can view the data in a read only format, users are unable to change or update the data, an example of a shared lock, could be a SELECT statement.

Answer 3

Oracle refers to concurrency as a metric which measures simultaneous access of the same data by many users. A multi-user database management system must provide adequate concurrency controls, so that data cannot be updated or changed improperly, compromising data integrity.