TRUNCATE — empty a table or set of tables
TRUNCATE [ TABLE ] name
[, ...] [ CASCADE | RESTRICT ]
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.
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.
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.