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Does truncate invoke delete trigger?
So let’s take both one by one: TRUNCATE – When we run the TRUNCATE command to delete all the rows of a table it actually doesn’t remove any row rather it deallocates the data pages. So in the case of the TRUNCATE command, triggers will not be fired because here no modification takes place.
Can you explain the truncate and delete with trigger?
TRUNCATE removes the data by deallocating the data pages used to store the table data. Trigger : TRUNCATE does not activate the delete triggers on the table. So you must be very careful while using TRUNCATE.
Can we use truncate in trigger?
TRUNCATE TABLE cannot activate a trigger because the operation does not log individual row deletions.
Can a TRUNCATE be rolled back?
Unlike DELETE , however, TRUNCATE deletes the pages the data is stored on, not the individual rows. A log of what pages are deleted is still written, so a TRUNCATE can still be rolled back, as the deletion of those pages is simply not committed.
When to use TRUNCATE vs delete?
Delete and truncate both commands can be used to delete data of the table. Delete is a DML command whereas truncate is DDL command. Truncate can be used to delete the entire data of the table without maintaining the integrity of the table. On the other hand , delete statement can be used for deleting the specific data.
How does truncate not run on delete trigger?
If there are any FOREIGN KEY constraints that reference the table, InnoDB processes TRUNCATE TABLE by deleting rows one by one, processing the constraints as it proceeds. If the FOREIGN KEY constraint specifies DELETE CASCADE, rows from the child (referenced) table are deleted, and the truncated table becomes empty.
How does a TRUNCATE TABLE statement in MySQL work?
TRUNCATE TABLE empties a table completely. It requires the DROP privilege. Logically, TRUNCATE TABLE is similar to a DELETE statement that deletes all rows, or a sequence of DROP TABLE and CREATE TABLE statements. To achieve high performance, TRUNCATE TABLE bypasses the DML method of deleting data.
How does the before delete trigger work in MySQL?
The succeeding BEFORE DELETE trigger will add a new row in the table Salary_logs before the delete query from Emp_data table is executed to delete a row. The trigger code is written as follows. Now, we will check the trigger by deleting a row from Emp_data table.
What’s the difference between a delete and a TRUNCATE TABLE?
Although TRUNCATE TABLE is similar to DELETE, it is classified as a DDL statement rather than a DML statement. It differs from DELETE in the following ways: Truncate operations drop and re-create the table, which is much faster than deleting rows one by one, particularly for large tables.