In SAP HANA I am used to create Calculation Views.
Previously I learned that Calculation Views (which after compilation are column-views) are to be prefered over Database-SQL-Views.
Now with CDS-Views I am not sure if this is still the case. Especially with regards to performance.
Also what is now the difference between a table function (which replaced scripted calculation views) and CDS Views?
Ok, this is a question that I believe requires some background to be answered.
A long, long time ago...
When SAP HANA was first developed, it heavily reused concepts and technology from other, already existing SAP products (TREX, P*TIME, MaxDB, Business Warehouse Accelerator).
One of the fundamental elements of the high query performance was (and is) the column store data-storage, which came in large parts from the TREX/BWA products. These products, in turn, had been solutions to very specific problems (full-text search for catalogs and speed-up of analytical queries from the SAP Business Warehouse data warehouse product).
Especially the BWA use case reflects in the column views of SAP HANA. Due to the limited use case of supporting SAP BW queries, no general SQL/relational query support was required (e.g. no arbitrary join-chain optimizations, no SQL features beyond SQL:92 etc.) whereas other, rather exotic features (like "vertical join") that could be used by SAP BW, were built into a query tool/engine ("engine" clearly was a very popular term with the SAP developers).
Once HANA proved successful as a platform to run SAP BW on, the next step was to add flexibility and make more general platforms like SAP Netweaver (the software that SAP's business solution products run on/with) working on SAP HANA. Now, SQL features were added and those required additional capabilities from the query optimizer and execution "engines".
Query optimization had to be flexible and fast and should lead to query performance that would still beat the existing RDBMS vendors' offering (which had been around for 40+ years).
This, clearly, is a hard problem and throwing is operational aspects of DB development (scaling, solution deployment, data federation, etc.).
This led to an overlapping development of different tools addressing different aspects of DB development.
SQL support and the underlying SQL optimizer were made more powerful, so much so, that (some) SQL queries could be as fast or faster than those modeled in calculation views. And since both of these "query frontends" eventually had to talk to the same internal data structures (row/column store) it was desirable to have just a single query optimizer, that would support all the different use cases.
Somewhere around HANA 1 SPS11/12 most calculation views started to be "unrolled" internally to feed into the common optimizer (that was what the "Execute in SQL Engine" flag was about).
I'd say, since then, the performance argument for using calculation views only holds in very specific circumstances.
I mentioned the overlapping developments and CDS (core data services) is one of them. The idea here is a very different one from SQL. While SQL gives you "the way to talk to the database", CDS wants to give your application a single data definition, that is used by the UI, the program logic and the data storage/query execution.
SQL != CDS
This probably needs some context (again): a major usage pattern of how SQL databases are used by application developers is that the application is written in some form of OO-implementation and the talking to the DB is left to a mapping layer/library (e.g. O/R-mappers). This means, that the knowledge of what the application is about (aka business process knowledge), is spread out in the application.
There is some information about it in the UI (labels, formatting, visibility, ...), some of it is in the application-object model (object dependencies, hierarchies, value domains...) and then some of it is in the queries against the database.
Such scattered knowledge/definition makes it hard to make changes consistent, which in turn, slows the development process and in turn prolongs the time until the application can run and deliver some positive outcome.
"Time-to-value" is the thing under optimization here as this is important for companies that give the promise of "success through innovation".
Ok, so this CDS thing is now part of the development models proposed by SAP and nearly en-passant also addresses topics like schema evolution and deployment of the data model. It is, in fact, independent of the actual database platform as shown in the CDS for ABAP variety.
How does this lead back to query performance? It does not really.
CDS' advantage is that one can provide more information about the data model than what is possible in HANA SQL.
Associations and joins with cardinality declaration (albeit now retrofitted to plain SQL) can enable the optimizer to use additional optimizations. Yet, the same optimizer and the same query execution "engines" are used here.
So, from a (query execution) performance point of view, it does not make a big difference, as long as no query semantics are required for which CDS does not have syntax (e.g. some window functions).
The main point of CDS really is about application development process performance and whether that works well with how you do development really depends on how much of it you can use.
Now for the question "scripted calc view" vs. "table function" vs. "CDS view".
Looking at these different object types from the point of "what can I do with them functionally?" will result in the observation "basically, the same".
The difference lies in how these can be optimized (scripted calc views cannot be generally unrolled into the global query to be optimized), and what one can do with the object once created.
Table functions allow for very easy reuse across multiple views and queries. They also provide the option to provide parameters into the function (similar to parameterized views) and in addition allow for imperative coding.
Functionally speaking, table functions are a kind of swiss-army knife; one can do nearly anything with them and they still can be part of global query optimization.
CDS views, as mentioned above, are nothing "special" in terms of query runtime or optimization. The main reason why CDS views are "a thing" is that with HANA SAP started to develop development models (such as XS, XSA, CAM) that revolve around "virtual data models".
The idea for those is that the structure of tables very often is stable and changes only little over time.
In a way, this is the "write-schema" of applications that enter the data into tables.
The "read-schema" is most of the time different from that. Queries re-combine the normalized data into records that the application can map into objects. This allows applications to look at the data differently than the original application.
With "virtual data models" these queries are baked into tangible development artifacts (the views) that can be reused across the application. In fact, these can be treated as if this was the database with its tables, presented in a way that makes sense for the application.
Once again, if that is something that is beneficial for your application development depends on how your application development looks like.
Can you use HANA without CDS? Absolutely, and there are many areas where CDS lacks (i.e. the limited syntax and feature mapping to HANA features) but it does have its merits.
Should you abandon calculation views?
I would not necessarily change existing developments if they still serve their purpose, but calculation views certainly are an odd development object. Training folks in using those and SQL most likely is overly expensive compared to just sticking to SQL.
Personally, I prefer the code-based SQL development (better tooling available, allows for easier comparison with other DBMS, doesn't require WEB IDE/HANA Studio).
The only thing, SQL based development does not provide is the extended annotations/semantic information used by the SAP analytic frontend tools (SAC & BO) - these really are specific to CDS and Information Models (calculation views) but barely used by other analytic tools.
And that's my take on it.
I would add that
Calculation Views are semantically richer. A SQL View does not know about measures, dimensions, hierarchies. https://blogs.sap.com/2019/08/26/what-is-the-difference-calcview-versus-sql-view/
The difference from the execution plan point of view is getting less and less. In Hana 2.0 SP4 most graphical calc views are turned internally into a single SQL statement to be executed by the SQL engine. So in that sense, using a CalcView gives you the additional information about the model plus the query performance of the SQL engine.
Lars' explanation of CDS is perfect. Nothing to add there.
But Imagine the situation when you can't create a table function because of limited license (aka runtime version). Just stay with scripted views.
The main advantage of Hana artifacts over CDS at present is the ability to use input parameters in complex cases to optimize resources and query performance - when your logic is pushed down into DB instead of AS / app. But many native SQL features are still not available in graphical views (for example - exists, JOIN on BETWEEN), so I think that 10 years later HANA artifacts will become "very rare".
So learn CDS syntax :)
Always a glad experience reading an article or pov from Lars, on any media (StackOverflow, SAP blog, article, twitter).
I just want to point out that another thing that I miss from the SQL scripting (SP, TF, SF) is the join optimization and SQL propagation that Information View has.
This is for me the focus to flexible models (apart from dynamic join that is only relevant for certain scenarios), to deliver one view that will perform depending on which columns the user or app will request.
For the semantics use, I can simply expose a TF inside an information view to add some.
You can tell me that CDS have both options available (join optimization, SQL propagation, and annotation) but for advanced or complicated scenarios (window functions not present at CDS), and also for non-SAP developers, it will be more simple and the go-to approach for beginners
What is the best considered way to save and use Views, SPs and UDFs for SSRS reporting services that will be used by many users and some reports subscribed being sent out?
Do I:
Write it to a table overnight via scheduled jobs to do a direct read to the pre-saved query results?
Use a SP with temp tables with indexes based on each Views SQL to have it all in one place for the SSRS?
If the answer is that 'it depends on what I want', I would be grateful if you point me to any resources that can give me an idea of ideal setup to get query data to SSRS with minimal performance issues.
Thanking you kindly
Background/Explanation
SQL Server is not foreign to me but I don’t consider myself experienced (1 year) enough in developing 'etiquette' when it comes to crafting the parts of SQL Server. I feel I'm developing a lot of bad habits formed from using basic SQL knowledge, online searches and the odd MS SQL server course. The amount of searching done has been endless and I’m not saying there isn’t an answer out there for each part of SQL Server (UDFs, SPs and Views) out there.
The company I work for has many servers, many databases, for many outsourced front end systems being used. The issue is performance and the more I search the more I realize the setup of our databases could now maybe completely negligent and amateur. When I joined the setup used a lot of views each 'end' view had a dependency tree of over 4+ views including use of functions, each view ranging from aggregate calculations for Statistics to rearranging via pivots and unpivots. The reason given to me was so that we can pick out the parts that have gone wrong in which view. To no surprise the server has now suddenly had enough of this and peaks at 100% every time a report or view ran affecting the front end systems performance for the users.
My PP stresses my frustration and my position with the company (code monkey) in finding an answer myself which has resulted in pushing the keys back in the keyboard with opposable thumbs and appeal to the experts here.
This question is really too broad for stackoverflow. I'll try to give you a quick overview of what I think you're asking but really you're asking for way too much for a single answer here. This site is mainly focused around solving a specific problem and not the general process of development. I expect someone will probably come along and close your question.
Nightly table loads
Depending on the complexity of the task this is exactly what SSIS (SQL Server Integration Services) is for. You can build automated processes that do data transformations and data loads. It is used to build maintainable data integration solutions. Learning to use SSIS (especially properly) is a whole task though. In fact the 3rd exam for the SQL Server 2012 MCSA is exclusively about SSIS. Though if your table loads are not that complicated running them as SQL Tasks could be just as effective.
Database structure and use of views/SPs/functions/etc
This is an incredibly deep subject and it is totally dependent on what you're trying to do, how your data is structured, what kind of hardware you've got running, etc. Certainly using views, functions, and stored procedures can be good. They enable code re-use and allow you to encapsulate the logic for SSRS reports away from the actual report writers.
However, the SQL needs to be well written or it will suffer from performance problems. But, of course, that is just how it is no matter where you put the code. Even if the SQL is just a dataset in an SSRS report it will run slowly and hammer the server if it isn't written well. If the database isn't configured correctly it can have terrible performance. Indexes and other techniques for speeding up databases will always be important.
Above all everything needs to be documented so that someone else (or your later self) can make sense of it in ten months when something breaks.
Training
I would highly recommend trying to convince your employer to send you on some courses to learn SQL Server if they expect you to be developing complex database solutions. Certainly taking the courses to get your MCSA in SQL Server 2012 would be very useful. Getting the certification certainly opened my eyes to many possibilities for achieving things that I didn't know about before or just hadn't thought of.
The first exam will cover writing SQL queries and the different things that can help performance and the many cool features that you can leverage when retrieving or writing data. The second exam will cover database server administration, troubleshooting, and some performance tuning. The third exam is all about SSIS and how to warehouse your data to enable better analysis and reporting.
Even if you just read the Microsoft Learning books for these exams and never take the tests you will gain a lot of knowledge. There are other books that are good too such as T-SQL Fundamentals by Itzik Ben-Gan but ultimately it sounds like you need to get a lot deeper knowledge of the SQL Server platform before you can really make good design decisions about how to implement your solutions.
Conclusion
In the end, programming is programming. Trying to make a maintainable solution that works is your first goal. Tuning the performance of the system comes after that. The specifics of the languages and platforms don't take away from any of that. But in order to get the best performance out of a system you need knowledge about that system. An answer on here isn't going to be able to give you everything you need to know.
I have a legacy VB6 app which I am rewriting in .Net. I have not used an ORM package before (being the old fashioned type who likes to know what SQL is being used), but I have seen good reports of NNibernate and I am tempted to use it for this project. I just want to check I won't be shooting myself in the foot.
Because my new app will initially run alongside the existing one, any ORM I use must work with the existing database schema. Also, I need to use SQL server text searching. From what I gather, LINQ to SQL does not support Text searching, so this will rule it out.
The app uses it's own method of allocating IDs for new objects - will NHibernate allow this or does it expect to use it's own mechanisms?
Also I have read that NHibernate does caching. I need to make sure that rows inserted outside of NHibernate are immediately accessible when accessing the database from NHibernate and vice versa.
There are 4 or 5 main tables and 10 or so subsidiary tables. although a couple of the main tables have up to a million rows, the app itself will normally be only returning a few. The user load is low so I don't anticipate performance being a problem.
At the moment I'm not sure whether it will be ASP.NET or win forms but either way I will be expecting to use data binding.
In terms of functionality, The app is not particulatly complicated - the budget to re-implement it is about 20 man days, so if I am going to use ORM it has to be something that will start paying for itself pretty quickly. Similarly I want the app to be simple to deploy and not require some monster enterprise framework.
Any thoughts on whether this is a suitable project for NHibernate would be much appreciated.
While ORMs are good, I personally wouldn't take on the risk of trying to use any ORM on a 20 day project if I had to absorb the ORM learning curve as I went.
If you have ADO.NET infrastructure you are comfortable with and you can live without ORM features, that is the much less risky approach to take.
You should learn ORMs and Linq (not necessarily Linq To Sql) eventually, but it's much more enjoyable when there is no immediate time pressure.
This sounds more like a risk management issue and that requires you to make a personal decision about how willing you are to see the project fail due to embracing new (to you) technologies.
You might also check out LLBL Gen Pro. It is a very mature ORM that handles a lot of different scenarios.
I have successfully fitted an NHibernate domain model to a few legacy database schemas - it's not yet proved impossible, but it is sometimes not without its difficulties. The easiest schemas to map are those where all primary keys and foreign keys are single column ones, but with so few tables you should be able to do the mapping relatively quickly even if this is not true of yours.
I strongly recommend, particularly given your timescale, that you use Fluent NHibernate to do your mappings - the time to learn the XML mapping file syntax may be too big an ask. However, you will need to use an XML mapping file for your full-text indexing stuff (assuming that's what you meant), writing these as named SQL queries. (See nhibernate.info documentation for details.)
Suggest you spend a day or two trying to create a model for a couple of your tables, and writing code to interact with them. There'll always be people on SO ready to answer any questions you have.
You may also want to take a look at Linq to NHibernate - we've found it helpful in terms of abstracting even more of our database access stuff away behind a simple interface. But it's Fluent NHibernate that will give you the biggest and quickest win in terms of "cheating" on the NHibernate learning curve.
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I took a look at the "Beginner's Guide to LINQ" post here on StackOverflow (Beginners Guide to LINQ), but had a follow-up question:
We're about to ramp up a new project where nearly all of our database op's will be fairly simple data retrievals (there's another segment of the project which already writes the data). Most of our other projects up to this point make use of stored procedures for such things. However, I'd like to leverage LINQ-to-SQL if it makes more sense.
So, the question is this: For simple data retrievals, which approach is better, LINQ-to-SQL or stored procs? Any specific pro's or con's?
Thanks.
Some advantages of LINQ over sprocs:
Type safety: I think we all understand this.
Abstraction: This is especially true with LINQ-to-Entities. This abstraction also allows the framework to add additional improvements that you can easily take advantage of. PLINQ is an example of adding multi-threading support to LINQ. Code changes are minimal to add this support. It would be MUCH harder to do this data access code that simply calls sprocs.
Debugging support: I can use any .NET debugger to debug the queries. With sprocs, you cannot easily debug the SQL and that experience is largely tied to your database vendor (MS SQL Server provides a query analyzer, but often that isn't enough).
Vendor agnostic: LINQ works with lots of databases and the number of supported databases will only increase. Sprocs are not always portable between databases, either because of varying syntax or feature support (if the database supports sprocs at all).
Deployment: Others have mentioned this already, but it's easier to deploy a single assembly than to deploy a set of sprocs. This also ties in with #4.
Easier: You don't have to learn T-SQL to do data access, nor do you have to learn the data access API (e.g. ADO.NET) necessary for calling the sprocs. This is related to #3 and #4.
Some disadvantages of LINQ vs sprocs:
Network traffic: sprocs need only serialize sproc-name and argument data over the wire while LINQ sends the entire query. This can get really bad if the queries are very complex. However, LINQ's abstraction allows Microsoft to improve this over time.
Less flexible: Sprocs can take full advantage of a database's featureset. LINQ tends to be more generic in it's support. This is common in any kind of language abstraction (e.g. C# vs assembler).
Recompiling: If you need to make changes to the way you do data access, you need to recompile, version, and redeploy your assembly. Sprocs can sometimes allow a DBA to tune the data access routine without a need to redeploy anything.
Security and manageability are something that people argue about too.
Security: For example, you can protect your sensitive data by restricting access to the tables directly, and put ACLs on the sprocs. With LINQ, however, you can still restrict direct access to tables and instead put ACLs on updatable table views to achieve a similar end (assuming your database supports updatable views).
Manageability: Using views also gives you the advantage of shielding your application non-breaking from schema changes (like table normalization). You can update the view without requiring your data access code to change.
I used to be a big sproc guy, but I'm starting to lean towards LINQ as a better alternative in general. If there are some areas where sprocs are clearly better, then I'll probably still write a sproc but access it using LINQ. :)
I am generally a proponent of putting everything in stored procedures, for all of the reasons DBAs have been harping on for years. In the case of Linq, it is true that there will be no performance difference with simple CRUD queries.
But keep a few things in mind when making this decision: using any ORM couples you tightly to your data model. A DBA has no freedom to make changes to the data model without forcing you to change your compiled code. With stored procedures, you can hide these sorts of changes to an extent, since the parameter list and results set(s) returned from a procedure represent its contract, and the innards can be changed around, just so long as that contract is still met.
And also, if Linq is used for more complex queries, tuning the database becomes a much more difficult task. When a stored procedure is running slow, the DBA can totally focus on the code in isolation, and has lots of options, just so that contract is still satisfied when he/she is done.
I have seen many, many cases where serious problems in an application were addressed by changes to the schema and code in stored procedures without any change to deployed, compiled code.
Perhaps a hybird approach would be nice with Linq? Linq can, of course, be used to call stored procedures.
Linq to Sql.
Sql server will cache the query plans, so there's no performance gain for sprocs.
Your linq statements, on the other hand, will be logically part of and tested with your application. Sprocs are always a bit separated and are harder to maintain and test.
If I was working on a new application from scratch right now I would just use Linq, no sprocs.
For basic data retrieval I would be going for Linq without hesitation.
Since moving to Linq I've found the following advantages:
Debugging my DAL has never been easier.
Compile time safety when your schema changes is priceless.
Deployment is easier because everything is compiled into DLL's. No more managing deployment scripts.
Because Linq can support querying anything that implements the IQueryable interface, you will be able to use the same syntax to query XML, Objects and any other datasource without having to learn a new syntax
LINQ will bloat the procedure cache
If an application is using LINQ to SQL and the queries involve the use of strings that can be highly variable in length, the SQL Server procedure cache will become bloated with one version of the query for every possible string length. For example, consider the following very simple queries created against the Person.AddressTypes table in the AdventureWorks2008 database:
var p =
from n in x.AddressTypes
where n.Name == "Billing"
select n;
var p =
from n in x.AddressTypes
where n.Name == "Main Office"
select n;
If both of these queries are run, we will see two entries in the SQL Server procedure cache: One bound with an NVARCHAR(7), and the other with an NVARCHAR(11). Now imagine if there were hundreds or thousands of different input strings, all with different lengths. The procedure cache would become unnecessarily filled with all sorts of different plans for the exact same query.
More here: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=363290
I think the pro LINQ argument seems to be coming from people who don't have a history with database development (in general).
Especially if using a product like VS DB Pro or Team Suite, many of the arguments made here do not apply, for instance:
Harder to maintain and Test:
VS provides full syntax checking, style checking, referential and constraint checking and more. It also provide full unit testing capabilities and refactoring tools.
LINQ makes true unit testing impossible as (in my mind) it fails the ACID test.
Debugging is easier in LINQ:
Why? VS allows full step-in from managed code and regular debugging of SPs.
Compiled into a single DLL rather than deployment scripts:
Once again, VS comes to the rescue where it can build and deploy full databases or make data-safe incremental changes.
Don't have to learn TSQL with LINQ:
No you don't, but you have to learn LINQ - where's the benefit?
I really don't see this as being a benefit. Being able to change something in isolation might sound good in theory, but just because the changes fulfil a contract doesn't mean it's returning the correct results. To be able to determine what the correct results are you need context and you get that context from the calling code.
Um, loosely coupled apps are the ultimate goal of all good programmers as they really do increase flexibility. Being able to change things in isolation is fantastic, and it is your unit tests that will ensure it is still returning appropriate results.
Before you all get upset, I think LINQ has its place and has a grand future. But for complex, data-intensive applications I do not think it is ready to take the place of stored procedures. This was a view I had echoed by an MVP at TechEd this year (they will remain nameless).
EDIT: The LINQ to SQL Stored Procedure side of things is something I still need to read more on - depending on what I find I may alter my above diatribe ;)
LINQ is new and has its place. LINQ is not invented to replace stored procedure.
Here I will focus on some performance myths & CONS, just for "LINQ to SQL", of course I might be totally wrong ;-)
(1)People say LINQ statment can "cache" in SQL server, so it doesn't lose performance. Partially true. "LINQ to SQL" actually is the runtime translating LINQ syntax to TSQL statment. So from the performance perspective,a hard coded ADO.NET SQL statement has no difference than LINQ.
(2)Given an example, a customer service UI has a "account transfer" function. this function itself might update 10 DB tables and return some messages in one shot. With LINQ, you have to build a set of statements and send them as one batch to SQL server. the performance of this translated LINQ->TSQL batch can hardly match stored procedure. Reason? because you can tweak the smallest unit of the statement in Stored procedue by using the built-in SQL profiler and execution plan tool, you can not do this in LINQ.
The point is, when talking single DB table and small set of data CRUD, LINQ is as fast as SP. But for much more complicated logic, stored procedure is more performance tweakable.
(3)"LINQ to SQL" easily makes newbies to introduce performance hogs. Any senior TSQL guy can tell you when not to use CURSOR (Basically you should not use CURSOR in TSQL in most cases). With LINQ and the charming "foreach" loop with query, It's so easy for a newbie to write such code:
foreach(Customer c in query)
{
c.Country = "Wonder Land";
}
ctx.SubmitChanges();
You can see this easy decent code is so attractive. But under the hood, .NET runtime just translate this to an update batch. If there are only 500 lines, this is 500 line TSQL batch; If there are million lines, this is a hit. Of course, experienced user won't use this way to do this job, but the point is, it's so easy to fall in this way.
The best code is no code, and with stored procedures you have to write at least some code in the database and code in the application to call it , whereas with LINQ to SQL or LINQ to Entities, you don't have to write any additional code beyond any other LINQ query aside from instantiating a context object.
LINQ definitely has its place in application-specific databases and in small businesses.
But in a large enterprise, where central databases serve as a hub of common data for many applications, we need abstraction. We need to centrally manage security and show access histories. We need to be able to do impact analysis: if I make a small change to the data model to serve a new business need, what queries need to be changed and what applications need to be re-tested? Views and Stored Procedures give me that. If LINQ can do all that, and make our programmers more productive, I'll welcome it -- does anyone have experience using it in this kind of environment?
A DBA has no freedom to make changes
to the data model without forcing you
to change your compiled code. With
stored procedures, you can hide these
sorts of changes to an extent, since
the parameter list and results set(s)
returned from a procedure represent
its contract, and the innards can be
changed around, just so long as that
contract is still met.
I really don't see this as being a benefit. Being able to change something in isolation might sound good in theory, but just because the changes fulfil a contract doesn't mean it's returning the correct results. To be able to determine what the correct results are you need context and you get that context from the calling code.
I think you need to go with procs for anything real.
A) Writing all your logic in linq means your database is less useful because only your application can consume it.
B) I'm not convinced that object modelling is better than relational modelling anyway.
C) Testing and developing a stored procedure in SQL is a hell of a lot faster than a compile edit cycle in any Visual Studio environment. You just edit, F5 and hit select and you are off to the races.
D) It's easier to manage and deploy stored procedures than assemblies.. you just put the file on the server, and press F5...
E) Linq to sql still writes crappy code at times when you don't expect it.
Honestly, I think the ultimate thing would be for MS to augment t-sql so that it can do a join projection impliclitly the way linq does. t-sql should know if you wanted to do order.lineitems.part, for example.
LINQ doesn't prohibit the use of stored procedures. I've used mixed mode with LINQ-SQL and LINQ-storedproc. Personally, I'm glad I don't have to write the stored procs....pwet-tu.
IMHO, RAD = LINQ, RUP = Stored Procs. I worked for a large Fortune 500 company for many years, at many levels including management, and frankly, I would never hire RUP developers to do RAD development. They are so siloed that they very limited knowledge of what to do at other levels of the process. With a siloed environment, it makes sense to give DBAs control over the data through very specific entry points, because others frankly don't know the best ways to accomplish data management.
But large enterprises move painfully slow in the development arena, and this is extremely costly. There are times when you need to move faster to save both time and money, and LINQ provides that and more in spades.
Sometimes I think that DBAs are biased against LINQ because they feel it threatens their job security. But that's the nature of the beast, ladies and gentlemen.
According to gurus, I define LINQ as motorcycle and SP as car.
If you want to go for a short trip and only have small passengers(in this case 2), go gracefully with LINQ.
But if you want to go for a journey and have large band, i think you should choose SP.
As a conclusion, choosing between motorcycle or car is depend on your route (business), length (time), and passengers (data).
Hope it helps, I may be wrong. :D
Also, there is the issue of possible 2.0 rollback. Trust me it has happened to me a couple of times so I am sure it has happened to others.
I also agree that abstraction is the best. Along with the fact, the original purpose of an ORM is to make RDBMS match up nicely to the OO concepts. However, if everything worked fine before LINQ by having to deviate a bit from OO concepts then screw 'em. Concepts and reality don't always fit well together. There is no room for militant zealots in IT.
I'm assuming you mean Linq To Sql
For any CRUD command it's easy to profile the performance of a stored procedure vs. any technology. In this case any difference between the two will be negligible. Try profiling for a 5 (simple types) field object over 100,000 select queries to find out if there's a real difference.
On the other hand the real deal-breaker will be the question on whether you feel comfortable putting your business logic on your database or not, which is an argument against stored procedures.
All these answers leaning towards LINQ are mainly talking about EASE of DEVELOPMENT which is more or less connected to poor quality of coding or laziness in coding. I am like that only.
Some advantages or Linq, I read here as , easy to test, easy to debug etc, but these are no where connected to Final output or end user. This is always going cause the trouble the end user on performance. Whats the point loading many things in memory and then applying filters on in using LINQ?
Again TypeSafety, is caution that "we are careful to avoid wrong typecasting" which again poor quality we are trying to improve by using linq. Even in that case, if anything in database changes, e.g. size of String column, then linq needs to be re-compiled and would not be typesafe without that .. I tried.
Although, we found is good, sweet, interesting etc while working with LINQ, it has shear disadvantage of making developer lazy :) and it is proved 1000 times that it is bad (may be worst) on performance compared to Stored Procs.
Stop being lazy. I am trying hard. :)
For simple CRUD operations with a single data access point, I would say go for LINQ if you feel comfortable with the syntax. For more complicated logic I think sprocs are more efficiant performance-wise if you are good at T-SQL and its more advanced operations. You also have the help from Tuning Advisor, SQL Server Profiler, debugging your queries from SSMS etc.
The outcome can be summarized as
LinqToSql for small sites, and prototypes. It really saves time for Prototyping.
Sps : Universal. I can fine tune my queries and always check ActualExecutionPlan / EstimatedExecutionPlan.
Create PROCEDURE userInfoProcedure
-- Add the parameters for the stored procedure here
#FirstName varchar,
#LastName varchar
AS
BEGIN
SET NOCOUNT ON;
-- Insert statements for procedure here
SELECT FirstName , LastName,Age from UserInfo where FirstName=#FirstName
and LastName=#FirstName
END
GO
http://www.totaldotnet.com/Article/ShowArticle121_StoreProcBasic.aspx
Stored procedure makes testing easier and you can change the query without touching the application code. Also with linq, getting a data does not mean its the right data. And testing the correctness of the data means running the application but with stored procedure it's easy to test without touching the application.
Both LINQ and SQL have their places. Both have their disadvantages and advantages.
Sometimes for complex data retrieval you might need stored procs. And sometimes you may want other people to use your stored proc in Sql Server Management Studio.
Linq to Entities is great for fast CRUD development.
Sure you can build an app using only one or the other. Or you can mix it up. It all comes down to your requirements. But SQL stored procs will no go away any time soon.