Question: What Happens When You Truncate A Table?

What will happen after truncate a table?

The TRUNCATE TABLE command deletes the data inside a table, but not the table itself..

How do you truncate data in a table?

The SQL TRUNCATE TABLE command is used to delete complete data from an existing table. You can also use DROP TABLE command to delete complete table but it would remove complete table structure form the database and you would need to re-create this table once again if you wish you store some data.

Does truncating a table reset the identity?

Effect of TRUNCATE statement TRUNCATE resets the identity value to the original seed value of the table.

How long does it take to truncate a table?

A millisecond or so. Truncate is O(1) – a pure metadata operation. This is assuming there is no concurrent activity on the table.

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 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.

What happens when you truncate a table in Oracle?

The TRUNCATE TABLE statement is used to remove all records from a table in Oracle. It performs the same function as a DELETE statement without a WHERE clause. Warning: If you truncate a table, the TRUNCATE TABLE statement can not be rolled back.

Which is better truncate or delete?

Truncate reseeds identity values, whereas delete doesn’t. Truncate removes all records and doesn’t fire triggers. Truncate is faster compared to delete as it makes less use of the transaction log.

What happens to indexes when you truncate a table?

When you truncate a table, Oracle Database automatically removes all data in the table’s indexes and any materialized view direct-path INSERT information held in association with the table. This information is independent of any materialized view log.

Does truncate delete table structure?

TRUNCATE TABLE is similar to DELETE , but this operation is a DDL (Data Definition Language) command. It also deletes records from a table without removing table structure, but it doesn’t use the WHERE clause.

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.

Is truncate faster than drop?

TRUNCATE is a DDL(Data Definition Language) command. It is used to delete all the tuples from the table. Like the DROP command, the TRUNCATE command also does not contain a WHERE clause. The TRUNCATE command is faster than both the DROP and the DELETE command.