What is the difference between DELETE and TRUNCATE?
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Answer Posted / brajendra arzare
Deletes perform normal DML. That is, they take locks on
rows, they generate redo and they require segments in the
UNDO tablespace. Deletes clear records out of blocks
carefully. If a mistake is made a rollback can be issued to
restore the records prior to a commit.
Truncates are DDL and truncate moves the High Water Mark
of the table back to zero. No row-level locks are taken, no
redo or rollback is generated.so they have the same effect
as a delete, but without all the overhead. Just one slight
problem: a truncate is a DDL command, so you can't roll it
back if you decide you made a mistake. (It's also true that
you can't selectively truncate -no "WHERE" clause is
permitted, unlike with deletes, of course).
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