PostgreSQL - TRUNCATE TABLE Command

 The PostgreSQL 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 from the database and you would need to re-create this table once again if you wish to store some data.

It has the same effect as DELETE on each table, but since it does not actually scan the tables, it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables.

Syntax

The basic syntax of TRUNCATE TABLE is as follows −

TRUNCATE TABLE  table_name;


Example

Consider the COMPANY table has the following records −

 id | name  | age | address    | salary
----+-------+-----+------------+--------
  1 | Paul  |  32 | California |  20000
  2 | Allen |  25 | Texas      |  15000
  3 | Teddy |  23 | Norway     |  20000
  4 | Mark  |  25 | Rich-Mond  |  65000
  5 | David |  27 | Texas      |  85000
  6 | Kim   |  22 | South-Hall |  45000
  7 | James |  24 | Houston    |  10000
(7 rows)

The following is the example to truncate −

testdb=# TRUNCATE TABLE COMPANY;

Now, COMPANY table is truncated and the following would be the output of SELECT statement −

testdb=# SELECT * FROM CUSTOMERS;
 id | name | age | address | salary
----+------+-----+---------+--------
(0 rows)

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