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Question:  What is difference between TRUNCATE & DELETE

Answer:
Answer posted by Scott on 2005-05-25 18:30:04: TRUNCATE is a DDL command and cannot be rolled back. All of the memory space is released back to the server. 
DELETE is a DML command and can be rolled back. 
 
Both commands accomplish identical tasks (removing all data from a table), but TRUNCATE is much faster.


November 11, 2005 04:56:46 #9
 Prangya Sahu   Member Since: Visitor    Total Comments: N/A 

What are the differences between TRUNCATE & DELETE
 

1>TRUNCATE is a DDL command whereas DELETE is a DML command.

2>TRUNCATE is much faster than DELETE.

Reason:When you type DELETE.all the data get copied into the Rollback Tablespace first.then delete operation get performed.Thatswhy when you type ROLLBACK after deleting a table ,you can get back the data(The system get it for you from the Rollback Tablespace).All this process take time.But when you type TRUNCATE,it removes data directly without copying it into the Rollback Tablespace.Thatswhy TRUNCATE is faster.Once you Truncate you cann't get back the data.

3>You cann't rollback in TRUNCATE but in DELETE you can rollback.TRUNCATE removes the record permanently.

4>In case of TRUNCATE ,Trigger doesn't get fired.But in DML commands like DELETE .Trigger get fired.

5>You cann't use conditions(WHERE clause) in TRUNCATE.But in DELETE you can write conditions using WHERE clause.

     

 

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