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From a maintenance perspective using ORM relieves the developers from
maintaining at the database level. You could develop all your core
and business logic in code and cover all the test cases and have the
need not to debug at the database level.It would be a good choice.
"Progress doesn't come from early risers – progress is made by lazy men looking for easier ways to do things." Lazarus Long
My advice would be to use an ORM (probably EF even though faster ones do exist) but keep a close eye on what the ORM is doing and learn how to performance tune it - in particular when not to use lazy loading.
( This is based on the economics of developer time being staggeringly expensive and hardware spectacularly cheap - if that does not apply in your situation then adjust accordingly. )
It is indeed.
But you need to keep in mind that it is largely due to how the test is setup. Loading a large amount of data into a collection.
That's not where EF or NHibernate excels. They are both defaulting to lazy loading the data. So if you mainly do CRUD you might not even notice that it's slower.
I might add that my own mapper is even faster, but that's not an ORM.
That specific test you can simply throw into the garbage.
You really can't compare cached data with raw.
And if he gets raw ado to be slower than any ORM, he doesn't know what he's doing. (most probably implicit conversions, GetValue instead of using the type specific Get, and using named Get instead of ordinal Get)
Which he on the other hand has in common with a lot of people.
A quick check of the code confirms my suspicions.
He returns datasets in his own homegrown "datalayer" that doesn't do anything the right way.
So I tested his code (with a different database though) and compared with my own (creating POCOs instead of a dataset) and it becomes a bit more than twice as fast, which is also the speed indicated by dapper.
As is often the case, there are reasons for and against using an ORM. Sadly, there are many extremists in both camps. I've worked on projects which do with and without ORMs.
Examples of reasons for (not exhaustive):
1. Avoid hardcoding SQL in your OO code
2. Makes unit testing easy in. Net
3. Repository out of the box
4. Can be very quick to setup
Examples of reasons against (not exhaustive):
1. Lots of business logic in the database layer
2. Difficult performance targets
3. Limited system resources (memory)
4. Tiny database - not worth the overhead
Then the question becomes which ORM.
Nhibernate comes from the Java world so you'd automatically be weary however, used right, it's fine. As someone on here already mentioned, you can still write direct SQL and call sprocs using it and just use nhibernate as the wrapper.
EF wasn't great in it's infancy and didn't play too well/at a with non-SQL servers but it's a big boy now and is much better. I'd use it over nhibernate if you can get the drivers for the database.
To ORM or not to ORM is not the question. The question is whether it's right for your project or more specifically, if it's right for your database/app model.
To rebut what someone said earlier, I'd argue that you should have a good knowledge of writing SQL and investigating performance whichever route you go.
I will not however that what you hit a problem with an ORM, particularly nhibernate which I've used in the past, you could be stuck for ages as the docs aren't great and there used to be lots of bugs but to be honest, this shouldn't happen so much nowadays unless you're trying to get super fancy. Still I haven't used nhibernate for 5 years.
Yes please. Although haven't touched NHibernate for a long time, Entity Framework has been doing the trick quite well.
It's much easier and faster to develop using ORM. If you know what you're doing, you won't have performance issues.
I once converted an app that was full SQL to Entity Framework and I actually observed performance gains. ORM sometimes optimizes what developers usually overlook. Lazy loading also helps a lot to improve performance in some scenarios.
Most of the time the benefits of ORM outweigh the benefits of pure SQL (or even SP) IMO.
To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson
Our heads are round so our thoughts can change direction - Francis Picabia
Honestly, ORMS are a square-peg/round-hole kind of solution.
Objects represent data hierarchically(sp?), RDBMS's represent data relationally. There is no sane way to glue the different models together in the general case. It's not even about speed, it's about RDBMS design - ORM's that "work" work by duplicating everything in the object hierarchy in some way or another, or produce so many relational links your DB will grind to a halt on even the most simple object storage/retrieval.
What you can (and should) do is (like the other poster said) write your database abstraction layer to turn objects into relations and vice-versa. At the abstraction layer you need to keep the object hierarchy pretty flat (1 level deep). Your program will then construct the objects into the hierarchy from the table abstraction.
I looked up ORM in Wikipedia. The following caught my eye:
Comparison with traditional data access techniques
Compared to traditional techniques of exchange between an object-oriented language and a relational database, ORM often reduces the amount of code that needs to be written.
Disadvantages of ORM tools generally stem from the high level of abstraction obscuring what is actually happening in the implementation code. Also, heavy reliance on ORM software has been cited as a major factor in producing poorly designed databases.
My nature, such as it is, would push me towards the roll-my-own methodology.