TRUNCATE [ TABLE ] name
The name of the table you wish to truncate. To truncate a table means to remove all rows from the table.
Use this command to remove all rows of a specified table. It does not scan through the table before removing data, making it rather helpful when emptying large tables of data. In essence, it is a quicker form of the DELETE command.
This example empties all of the rows in the temp_emp table:
booktown=# TRUNCATE TABLE temp_emp; TRUNCATE