How does truncate work in SQL?

Why use truncate instead of delete?

Truncate removes all records and doesn’t fire triggers. Truncate is faster compared to delete as it makes less use of the transaction log. Truncate is not possible when a table is referenced by a Foreign Key or tables are used in replication or with indexed views.

How do I truncate a SQL Server database?

A solution that can TRUNCATE all tables

  1. Create a table variable to store the constraint drop and creation scripts for the database.
  2. Load the data for all tables in the database.
  3. Execute a cursor to drop all constraints.
  4. Truncate all tables.
  5. Recreate all the constraints.

Which is better delete or truncate?

Unlike the DELETE command, the TRUNCATE command is fast. We cannot rollback the data after using the TRUNCATE command.

Difference between DELETE and TRUNCATE.

S.NO Delete Truncate
6. DELETE command is slower than TRUNCATE command. While TRUNCATE command is faster than DELETE command.

Why is TRUNCATE faster than DELETE?

TRUNCATE is faster than DELETE , as it doesn’t scan every record before removing it. TRUNCATE TABLE locks the whole table to remove data from a table; thus, this command also uses less transaction space than DELETE . Unlike DELETE , TRUNCATE does not return the number of rows deleted from the table.

Which is faster TRUNCATE or DROP?

TRUNCATE is a DDL(Data Definition Language) command. It is used to delete all the tuples from the table. … The TRUNCATE command is faster than both the DROP and the DELETE command. Like the DROP command we also can’t rollback the data after using the this command.

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Does truncate free space?

Truncating a table does not give any free space back to the disk – you need to run a SHRINKDATABASE operation for the allocated space to be successfully de-allocated and returned to the disk. Also, as others have mentioned, maybe the table was not taking up much space in the first place.

Is truncate a DDL command?

Although TRUNCATE TABLE is similar to DELETE , it is classified as a DDL statement rather than a DML statement. It differs from DELETE in the following ways: Truncate operations drop and re-create the table, which is much faster than deleting rows one by one, particularly for large tables.

Can you truncate a column in SQL?

What is the Truncate Command in SQL? We use the Truncate command to delete the data stored in the table. The working of truncate command is similar to the working of Delete command without a where clause.

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