Performance Optimization of application/product

Performance Optimization of application/product

Data Archiving Procedures

Data Archiving Procedures

Difference between TRUNCATE and DELETE in SQL Server?

TRUNCATE:

• It is a DDL command
• It does not support WHERE clause/condition
• Removes all the data all the time
• Faster than DELETE as it locks entire table
• It removes the data by deallocating the data pages used to store the table’s data, and only the page deallocations are recorded in the transaction log It does not activate triggers
• Table identity column is reset to seed value

Syntax:

TRUNCATE TABLE TableName

DELETE:

• It is DML command
• It supports WHERE clause/condition
• Removes data based on conditions specified in the WHERE clause (removes all the data if there is no WHERE clause) Slower than TRUNCATE as it takes row level locks
• It removes rows one at a time and records an entry in the transaction log for each deleted row
• It does activate triggers
• Table identity column is not reset

Syntax:

DELETE FROM TableName WHERE ColName = ‘YourCondition’

Note

Truncate and Delete both are logged operations and both can be rolled back when they are within transactions. It is myth that Truncate is not logged operations. It is indeed logged operations and it locks page level deallocations.

Fundamentals of Garbage Collection

In the common language runtime (CLR), the garbage collector serves as an automatic memory manager. It provides the following benefits:

• Enables you to develop your application without having to free memory.
• Allocates objects on the managed heap efficiently.
• Reclaims objects that are no longer being used, clears their memory, and keeps the memory available for future allocations. Managed objects automatically get clean content to start with, so their constructors do not have to initialize every data field.
• Provides memory safety by making sure that an object cannot use the content of another object.

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