Why is parameterized SQL generated by NHibernate just as fast as a stored procedure?

Question

One of my co-workers claims that even though the execution path is cached, there is no way parameterized SQL generated from an ORM is as quick as a stored procedure. Any hel

Answer 1

I've had this argument many times over.
Almost always I end up grabbing a really good dba, and running a proc and a piece of code with the profiler running, and get the dba to show that the results are so close its negligible.

Answer 2

Even if the stored procedure is 10% faster (it probably isn't), you may want to ask yourself how much it really matters. What really matters in the end, is how easy it is to write and maintain code for your system. If you are coding a web app, and your pages all return in 0.25 seconds, then the extra time saved by using stored procedures is negligible. However, there can be many added advantages of using an ORM like NHibernate, which would be extremely hard to duplicate using only stored procedures.

Answer 3

Round 1 - You can start a profiler trace and compare the execution times.

Answer 4

It is just as fast if the query is the same each time. Sql Server 2005 caches query plans at the level of each statement in a batch, regardless of where the SQL comes from.

The long-term difference might be that stored procedures are many, many times easier for a DBA to manage and tune, whereas hundreds of different queries that have to be gleaned from profiler traces are a nightmare.

Answer 5

For most people, the best way to convince them is to "show them the proof." In this case, I would create a couple basic test cases to retrieve the same set of data, and then time how long it takes using stored procedures versus NHibernate. Once you have the results, hand it over to them and most skeptical people should yield to the evidence.

Answer 6

The additional layer of abstraction will cause it to be slower than a pure call to a sproc. Just by the fact that you have additional allocations on the managed heap, and additional pushes and pops off the callstack, the truth of the matter is that it is more efficient to call a sproc over having an ORM build the query, regardless how good the ORM is.

How slow, if its even measurable, is debatable. This is also helped by the fact that most ORM's have a caching mechanism to avoid doing the query at all.