Why Truncate Is DDL?

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 you truncate?

To truncate a number, we miss off digits past a certain point in the number, filling-in zeros if necessary to make the truncated number approximately the same size as the original number. To truncate a number to 1 decimal place, miss off all the digits after the first decimal place.

Does truncate free space?

If you’re using innodb_file_per_table=ON, or you’re using MyISAM, TRUNCATE TABLE will delete the table files used by the table in question (and create new, empty ones). So, the space used will be released to the file system, and in Unix/Linux, “df” on the file system will show new space.

Does truncate need commit?

The TRUNCATE TABLE statement is a DDL command, so it includes an implicit COMMIT , so there is no way to issue a ROLLBACK if you decide you didn’t want to remove the rows. … The TRUNCATE TABLE statement can remove the storage associated with the table, or leave it to be reused later.

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 . … It also resets the table auto-increment value to the starting value (usually 1).

Can we truncate database?

In order to truncate all tables in your database you must first remove all the foreign key constraints, truncate the tables, and then restore all the constraints. … Load the data for all tables in the database. Execute a cursor to drop all constraints. Truncate all tables.

Can we rollback truncate in SQL?

You cannot ROLLBACK TRUNCATE Simply, you cannot rollback a transaction if it is already committed but you can do something else to get the data back (or at least some parts of it). When you execute the TRUNCATE statement, your data is still in the MDF file.

Can truncate have where condition?

TRUNCATE cannot be executed with a WHERE clause means that all records will be removed from the TRUNCATE / statement. However, partitions can be truncated as shown in the below T-SQL statement. From the above statement, partitions 2,4,6,7,8 will be truncated leaving the other partitions data will not be truncated.

Is truncate a DDL?

In SQL, the TRUNCATE TABLE statement is a Data Definition Language (DDL) operation that marks the extents of a table for deallocation (empty for reuse). The result of this operation quickly removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.

Is delete DDL or DML?

DML is Data Manipulation Language which is used to manipulate data itself. For example: insert, update, delete are instructions in SQL. It stands for Data Definition Language. … Basic command present in DDL are CREATE, DROP, RENAME, ALTER etc.

What is the use of truncate command in SQL?

TRUNCATE TABLE removes all rows from a table, but the table structure and its columns, constraints, indexes, and so on remain. To remove the table definition in addition to its data, use the DROP TABLE statement.

Is delete DML?

DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.