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.
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.
TRUNCATE will not run any user-defined ON DELETE triggers that might exist for the tables.
There are difference between truncate on PostgreSQL and Oracle.
truncate table X;
rollback; -- on Oracle is no rolback now
On Oracle you can't roll it back after truncate.