Do transactions add overhead to the DB?

Question

Would it add overhead to put a DB transactions around every single service method in our application?

We currently only use DB transactions where it's an explicit/obvious necessity. I have recently suggested transactions around all service methods, but some other developers asked the prudent question: will this add overhead?

My feeling is not - auto commit is the same as a transaction from the DB perspective. But is this accurate?

DB: MySQL

Answer 1

You are right, with autocommit every statement is wrapped in transaction. If your service methods are executing multiple sql statements, it would be good to wrap them into a transaction. Take a look at this answer for more details, and here is a nice blog post on the subject.

And to answer your question, yes, transactions do add performance overhead, but in your specific case, you will not notice the difference since you already have autocommit enabled, unless you have long running statements in service methods, which will cause longer locks on tables participating in transactions. If you just wrap your multiple statements inside a transaction, you will get one transaction (instead of transaction for every individual statement), as pointed here ("A session that has autocommit enabled can perform a multiple-statement transaction by starting it with an explicit START TRANSACTION or BEGIN statement and ending it with a COMMIT or ROLLBACK statement") and you will achieve atomicity on a service method level...

At the end, I would go with your solution, if that makes sense from the perspective of achieving atomicity on a service method level (which I think that you want to achieve), but there are + and - effects on performance, depending on your queries, requests/s etc...