DELETE TABLE is a logged operation, so the deletion of each row
gets logged in the transaction log, which makes it slow. TRUNCATE TABLE
also deletes all the rows in a table, but it won’t log the deletion of
each row, instead it logs the deallocation of the data pages of the
table, which makes it faster. Of course, TRUNCATE TABLE can be rolled
back. TRUNCATE TABLE is functionally identical to DELETE statement with
no WHERE clause: both remove all rows in the table. But TRUNCATE TABLE
is faster and uses fewer system and transaction log resources than
DELETE. The DELETE statement removes rows one at a time and records an
entry in the transaction log for each deleted row. TRUNCATE TABLE
removes the data by deallocating the data pages used to store the
table’s data, and only the page deallocations are recorded in the
transaction log. TRUNCATE TABLE removes all rows from a table, but the
table structure and its columns, constraints, indexes and so on remain.
The counter used by an identity for new rows is reset to the seed for
the column. If you want to retain the identity counter, use DELETE
instead. If you want to remove table definition and its data, use the
DROP TABLE statement. You cannot use TRUNCATE TABLE on a table
referenced by a FOREIGN KEY constraint; instead, use DELETE statement
without a WHERE clause. Because TRUNCATE TABLE is not logged, it cannot
activate a trigger. TRUNCATE TABLE may not be used on tables
participating in an indexed view
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