Will Truncation of Fire Suppression Trigger be Possible?

This article explains why truncating fire suppression triggers may not be possible due to certain restrictions imposed by MySQL.

Will Truncation of Fire Suppression Trigger be Possible?

Truncate statements do not trigger triggers, unlike the delete trigger in the DELETE statement. Logically, truncating a table is similar to a DELETE statement that deletes all rows or a sequence of DROP TABLE and CREATE TABLE statements. For high performance, it is better to skip the DML method of deleting data. Therefore, it cannot be undone, it does not cause the ON DELETE triggers to fire, and cannot be done for InnoDB tables with parent-child foreign key relationships. The problem with triggers is that they run even if you don't want them to.

Triggers can be a good option if there is an external tool that accesses and inserts data into your database and cannot access the code, but you need to add some functionality in the insert, delete, and update clauses. The difficulty with a trigger is that it does things behind your back; the developer who maintains the app might easily not realize it's there and make changes that screw things up without even realizing it. This creates a layer of complexity that only adds maintenance work. When the rollback trigger runs, Adaptive Server aborts the currently running command and stops the rest of the trigger from running. User_triggers is the table in which all the created triggers are located, specific to the schema.

Therefore, SELECT THE USER_TRIGGERS STATUS WHERE TRIGGER_NAME %3D 'the_trigger_name'; it will get the status of ENABLED or DISABLED. Truncate deletes all records and does not trigger triggers. Truncation is faster compared to deletion since it makes less use of the transaction log. Truncation is not possible when a foreign key references a table or if the tables are used in replication or with indexed views. Triggers can be people, places, or things, as well as smells, words, or colors.

Emotional triggers are automatic responses to how others express their emotions, such as anger or sadness. For example, you may have no problem interacting with an angry person, but you find it difficult to deal with someone who cries. During a traumatic event, the brain often embeds sensory stimuli in memory. Even when a person finds the same stimuli in another context, they associate triggers with trauma. In some cases, a sensory trigger can trigger an emotional reaction before a person realizes why they are upset. Yes, you can commit within the trigger.

But for this, you need to make this trigger transaction a separate transaction from your main transaction; you can do it using Pragma. Pragma AUTONOMOUS_TRANSACTION allows you to create an independent (secondary) transaction initiated by another. A trigger is triggered within the transaction that modifies the data in the table. Triggers of this type will not slow down operations; however, they will ensure docking and data integrity. Yeah, a table with a trigger won't work as well as it would without it.

Logic dictates that doing something is more expensive than doing nothing. The trigger is definitely executed but any column check returns false. This is the exact opposite of an INSERT where each column returns true. A trigger triggered by a DELETE statement will always report that no column was updated. TRUNCATE will not trigger any ON DELETE triggers that may exist for tables; however, it will trigger ON TRUNCATE triggers. If ON TRUNCATE triggers are defined for any of the tables, all BEFORE TRUNCATE triggers are fired before any truncation occurs and all AFTER TRUNCATE triggers are fired after the last truncation is performed and sequences are reset.

Triggers will fire in the order in which tables will be processed (first those listed in the command and then those that were added due to cascading). In cases where you want all data in the table to be deleted and counter reset to 1, truncating can help you. Truncation operations delete and recreate the table which is much faster than deleting rows one by one especially for large tables. MySQL does not allow users to truncate tables referenced as FOREIGN KEY in another table. If FOREIGN KEY constraint specifies DELETE CASCADE then rows in child (referenced) table are deleted and truncated table becomes empty.

TRUNCATE TABLE removes data by de-allocating data pages used to store table data and records only page deallocations in transaction log. TRUNCATE acquires an ACCESS EXCLUSIVE lock on each table it operates on which blocks all other simultaneous operations on table. If there are any FOREIGN KEY constraints that reference table then InnoDB processes TRUNCATE TABLE by deleting rows one by one and processing constraints as it progresses. Here I think minimal resources mean that you can restore Truncate instructions for particular session but if you close connection then you won't be able to restore your data. To truncate a table you need at least ALTER permissions on table (which is granted by default to table owner members of sysadmin fixed server role and fixed database roles db_owner and db_ddladmin). The DELETE command does not change structure of table in any way such as how TRUNCATE modifies identity column by resetting its value. Since TRUNCATE does not make any data changes to table that's why DELETE TRIGGER is not called.

Since TRUNCATE resets identity column counter if you want to keep identity counter use DELETE instead of TRUNCATE.

Charlotte Wilson
Charlotte Wilson

Friendly travel advocate. Freelance zombie scholar. Extreme web practitioner. Evil coffee buff. Professional beer practitioner.

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