¿Es mejor tener un simple disparador para insertar / actualizar / eliminar, o múltiple?

Question

Tengo un requisito para reflejar las operaciones de inserción / actualización / eliminar de una tabla a otra. Por ejemplo, el inserto en Tablea debe copiarse en la Tabla, actualizar a Tablea aplicada a la Tabla y eliminar de la tabla se aplicará a la Tabla. Es tan simple como eso, excepto la TEBEB tiene 1 columna adicional para un valor constante, se necesitan desencadenantes muy simples.

No estoy seguro de si es mejor escribir 3 desencadenantes separados, o tener un gatillo que hace todas las operaciones.

Esto es para 3 bases de datos: Sybase ASE, MSSQL y Oracle, y me gustaría mantenerlo en la solución similar (así que 3 para todas las bases de datos o 1 para todos ellos).

¿Es solo una cuestión de preferencia, tener 3 activadores contra 1, o hay beneficios reales para cualquiera de las soluciones?

Answer 1

Assuming that you actually need a trigger and that table B cannot simply be defined as a view on top of table A or that table B cannot just be defined with a foreign key that references a row in A along with the constant, that A cannot be redefined to add the additional column (potentially with a default value of the constant), one trigger at least lets you keep all the related logic in one place rather than having multiple places that need to be updated when you do something like add a new column to A. But I would be extremely wary of any architecture that involved having two different tables reflecting essentially the same data in both. That violates normalization, it adds to the system's I/O workload, and it makes the whole system more complex.

Answer 2

There's no efficiency to be gained by separating the triggers, other than the loss of efficiency of the trigger execution itself, when trying to determine what the action on Table A was.

IE 3 separate triggers can employ no validation logic to determine what just occurred on Table A, since the trigger being fired itself can behave in a bubble because it knows since it's firing, it was due to single action.

Whereas a 3-in-1 trigger, you must check the status of the virtual deleted and inserted tables and derive the action each and every time it's fired.

If you're not worried about the (admittedly small) performance impact of deriving the "action", or maybe don't even need to know in Table B the "action" that just occurred on Aable A...then I think 1 is perfectly fine.