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12.108 TRUNCATE

Name

TRUNCATE -- empty a table or set of tables

Synopsis

TRUNCATE [ TABLE ] name [, ...] [ CASCADE | RESTRICT ]

Description

TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. This is most useful on large tables.

Parameters

name

The name (optionally schema-qualified) of a table to be truncated.

CASCADE

Automatically truncate all tables that have foreign-key references to any of the named tables, or to any tables added to the group due to CASCADE.

RESTRICT

Refuse to truncate if any of the tables have foreign-key references from tables that are not to be truncated. This is the default.

Notes

Only the owner of a table may TRUNCATE it.

TRUNCATE cannot be used on a table that has foreign-key references from other tables, unless all such tables are also truncated in the same command. Checking validity in such cases would require table scans, and the whole point is not to do one. The CASCADE option can be used to automatically include all dependent tables--but be very careful when using this option, else you might lose data you did not intend to!

TRUNCATE will not run any user-defined ON DELETE triggers that might exist for the tables.

Examples

Truncate the tables bigtable and fattable:

TRUNCATE TABLE bigtable, fattable;

Truncate the table othertable, and cascade to any tables that are referencing othertable via foreign-key constraints:

TRUNCATE othertable CASCADE;

Compatibility

There is no TRUNCATE command in the SQL standard.