Exclusive lock - Multiple updates cannot be made to same resource at same time - Database

Discussion

• Nirja Shah   -Posted on 02 Nov 15
  - The different types of locks are as follows:
  Shared (S)
  - It is used for read operations that do not change or update data, such as a SELECT statement.
  
  Update (U)
  - They are used on resources that can be updated. Prevents a common form of deadlock that occurs when multiple sessions are reading, locking, and potentially updating resources later.
  
  Exclusive (X)
  - They are used for data-modification operations, such as INSERT, UPDATE, or DELETE. Ensures that multiple updates cannot be made to the same resource at the same time.
  
  Intent
  - They are used to establish a lock hierarchy. The types of intent locks are: intent shared (IS), intent exclusive (IX), and shared with intent exclusive (SIX).
  
  Schema
  - They are used when an operation dependent on the schema of a table is executing. The types of schema locks are: schema modification (Sch-M) and schema stability (Sch-S).
  
  Bulk Update (BU)
  - They are used when bulk copying data into a table and the TABLOCK hint is specified.
  
  Key-range
  - It protects the range of rows read by a query when using the serializable transaction isolation level.
  - It ensures that other transactions cannot insert rows that would qualify for the queries of the serializable transaction if the queries were run again.

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