What are Dynamic Management Functions (DMF) and Views (DMV) in SQL Server 2005/2008 ?
Dynamic Management Views and Functions (Transact-SQL) documentation:
Dynamic management views and functions return server state information that can be used to monitor the health of a server instance, diagnose problems, and tune performance.
Dynamic management views and functions return internal, implementation-specific state data. Their schemas and the data they return may change in future releases of SQL Server. Therefore, dynamic management views and functions in future releases may not be compatible with the dynamic management views and functions in this release. For example, in future releases of SQL Server, Microsoft may augment the definition of any dynamic management view by adding columns to the end of the column list. We recommend against using the syntax SELECT * FROM dynamic_management_view_name in production code because the number of columns returned might change and break your application.
The link includes more information, including a breakdown of the views & functions along with more specific information...
Introduced in SQL Server 2005 they provide a consistent way to look at the internals of SQL Server instances which previously required a fair bit of hacks. They provide the administrator about the various state of the SQL Server instances - for example sessions, memory etc.
This is the quote Ian W. Stirk
As queries run on a SQLServer database, SQLServer automatically records informa-tion
about the activity that’s taking place, internally into structures in memory;
you can access this information via DMVs.
DMVs are basically SQLviews on some pretty important internal memory structures.
For more knowlage see this link and read this ebook : SQL Server DMVs in Action
Related
To find out how often SQL Server users use certain objects (mostly views), I would like to log who queried the object when. If possible, I would also like to indicate in the log whether the object was called directly or if the query was part of a chain. I suspect that policies can be of use here, but did not find an example.
The answer is "Audits" in the server and database security sections in Management Studio. We are using Enterprise Edition, so "Fine Grained Auditing" is available to us. It covers the requirements in question, even including the sql statement used to query the object.
Other editions offer "Basic Auditing", not sure how much that will give you.
I have 2 MSSQL databases in 2 servers and I need to replicate amendments in schema and in particular tables. Most preferably I need SQL commands to do so. The system should be able to take a snapsnot of initial state of the database and later generate an SQL that would display the changes.
I need to record only particular tables changes in data and I also need to detect changes in table format (alterations of schema). It is desirable that manual adjustment of replication SQL would be possible (so only necessary changes are reflected, in case automated rules allow some unnecessary queries to end up in the patch.
Thanks !
Have a look at RedGate SQL Developer bundle. Unfortunately I'm not aware of any good open source tool for MS SQL Server.
I think that especially SQL Compare could be helpfull for you. If you are using Visual Studio Team Edition, you can have a look at the VS Database projects. I've heard that some teams are successfully using it for their database change management, but I never tried it myself.
The application part of my database is in Access 2003, and I use tables that are linked from SQL server. Now, I have some tables that I have to link from an Oracle database. I link them through and ODBC connection and it works fine. Is it possible to link that Oracle link in SQL and then link that table as it is already linked in Access 2003? So, I want to use just one ODBC connection to SQL server and in SQL Server link that Oracle link.
Yes, I believe the double indirection structure you suggest should work "OK". That's because MS_SQL linked server sources are handled very much like local databases and can be queried individually, i.e. within queries not involving local databases.
Do note, however, that it could be much less efficient, since you introduce an extra "hop". Also, do look for possible issues with regards to type mapping as some types in oracle may get mapped to a slightly different type in SQL than when accessed directly from MS-Access. Such type mapping issues would however be easy to work-around.
Edit: To "establish a connection" between MS-SQL and Oracle servers
This concept is known as "linked server" in MS-SQL lingo. See this MSDN article for an overview and details about sp_addlinkedserver Stored Procedure. This latter document provides the connection parameters required for various sources, including Oracle or ODBC (i.e. for Oracle you can either use ODBC, which is generally easier but less efficient, and for Oracle versions 8 and up, an OLE DB driver, which as implied may be harder to confure, but provide better performance).
Again, even with the gain associated with the Oracle OLE DB driver, the extra hop may hinder the overall performance of your setup...
Bear in mind here, I am not an Access guru. I am proficient with SQL Server and .Net framework. Here is my situation:
A very large MS Access 2007 application was built for my company by a contractor.
The application has been split into two tiers BY ACCESS; there is a front end portion that holds all of the Ms Access forms, and then on the back end part, which are access tables, queries, etc., that is stored on a computer on the network.
Well, of course, there is a need to convert the data storage portion to SQL Server 2005 while keeping all of these GUI forms which were built in Ms Access. This is where I come in.
I have read a little, and have found that you can link the forms or maybe even the access tables to SQL Server tables, but I am still very unsure on what exactly can be done and how to do it.
Has anyone done this? Please comment on any capabilities, limitations, considerations about such an undertaking. Thanks!
Do not use the upsizing wizard from Access:
First, it won't work with SQL Server 2008.
Second, there is a much better tool for the job:
SSMA, the SQL Server Migration Assistant for Access which is provided for free by Microsoft.
It will do a lot for you:
move your data from Access to SQL Server
automatically link the tables back into Access
give you lots of information about potential issues due to differences in the two databases
keeps track of the changes so you can keep the two synchronised over time until your migration is complete.
I wrote a blog entry about it recently.
You have a couple of options, the upsizing wizard does a decent(ish) job of moving structure and data from access to Sql. You can then setup linked tables so your application 'should' work pretty much as it does now. Unfortunately the Sql dialect used by Access is different from Sql Server, so if there are any 'raw sql' statements in the code they may need to be changed.
As you've linked to tables though all the other features of Access, the QBE, forms and so on should work as expected. That's the simplest and probably best approach.
Another way of approaching the issue would be to migrate the data as above, and then rather than using linked tables, make use of ADO from within access. That approach is kind of famaliar if you're used to other languages/dev environments, but it's the wrong approach. Access comes with loads of built in stuff that makes working with data really easy, if you go back to use ADO/Sql you then lose many of those benefits.
I suggest start on a small part of the application - non essential data, and migrate a few tables and see how it goes. Of course you back everything up first.
Good luck
Others have suggested upsizing the Jet back end to SQL Server and linking via ODBC. In an ideal world, the app will work beautifully without needing to change anything.
In the real world, you'll find that some of your front-end objects that were engineered to be efficient and fast with a Jet back end don't actually work very well with a server database. Sometimes Jet guesses wrong and sends something really inefficient to the server. This is particular the case with mass updates of records -- in order not to hog server resources (a good thing), Jet will send a single UPDATE statement for each record (which is a bad thing for your app, since it's much, much slower than a single UPDATE statement).
What you have to do is evaluate everything in your app after you've upsized it and where there are performance problems, move some of the logic to the server. This means you may create a few server-side views, or you may use passthrough queries (to hand off the whole SQL statement to SQL Server and not letting Jet worry about it), or you may need to create stored procedures on the server (especially for update operations).
But in general, it's actually quite safe to assume that most of it will work fine without change. It likely won't be as fast as the old Access/Jet app, but that's where you can use SQL Profiler to figure out what the holdup is and re-architect things to be more efficient with the SQL Server back end.
If the Access app was already efficiently designed (e.g., forms are never bound to full tables, but instead to recordsources with restrictive WHERE clauses returning only 1 or a few records), then it will likely work pretty well. On the other hand, if it uses a lot of the bad practices seen in the Access sample databases and templates, you could run into huge problems.
It's my opinion that every Access/Jet app should be designed from the beginning with the idea that someday it will be upsized to use a server back end. This means that the Access/Jet app will actually be quite efficient and speedy, but also that when you do upsize, it will cause a minimum of pain.
This is your lowest-cost option. You're going to want to set up an ODBC connection for your Access clients pointing to your SQL Server. You can then use the (I think) "Import" option to "link" a table to the SQL Server via the ODBC source. Migrate your data from the Access tables to SQL Server, and you have your data on SQL Server in a form you can manage and back up. Important, queries can then be written on SQL Server as views and presented to the Access db as linked tables as well.
Linked Access tables work fine but I've only used them with ODBC and other databases (Firebird, MySQL, Sqlite3). Information on primary or foreign keys wasn't passing through. There were also problems with datatype interpretation: a date in MySQL is not the same thing as in Access VBA. I guess these problems aren't nearly as bad when using SQL Server.
Important Point: If you link the tables in Access to SQL Server, then EVERY table must have a Primary Key defined (Contractor? Access? Experience says that probably some tables don't have PKs). If a PK is not defined, then the Access forms will not be able to update and insert rows, rendering the tables effectively read-only.
Take a look at this Access to SQL Server migration tool. It might be one of the few, if not the ONLY, true peer-to-peer or server-to-server migration tools running as a pure Web Application. It uses mostly ASP 3.0, XML, the File System Object, the Data Dictionary Object, ADO, ADO Extensions (ADOX), the Dictionary Scripting Objects and a few other neat Microsoft techniques and technologies. If you have the Source Access Table on one server and the destination SQL Server on another server or even the same server and you want to run this as a Web Internet solution this is the product for you. This example discusses the VPASP Shopping Cart, but it will work for ANY version of Access and for ANY version of SQL Server from SQL 2000 to SQL 2008.
I am finishing up development for a generic Database Upgrade Conversion process involving the automated conversion of Access Table, View and Index Structures in a VPASP Shopping or any other Access System to their SQL Server 2005/2008 equivalents. It runs right from your server without the need for any outside assistance from external staff or consultants.
After creating a clone of your Access tables, indexes and views in SQL Server this data migration routine will selectively migrate all the data from your Access tables into your new SQL Server 2005/2008 tables without having to give out either your actual Access Database or the Table Contents or your passwords to anyone.
Here is the Reverse Engineering part of the process running against a system with almost 200 tables and almost 300 indexes and Views which is being done as a system acceptance test. Still a work in progress, but the core pieces are in place.
http://www.21stcenturyecommerce.com/SQLDDL/ViewDBTables.asp
I do the automated reverse engineering of the Access Table DDLs (Data Definition Language) and convert them into SQL equivalent DDL Statements, because table structures and even extra tables might be slightly different for every VPASP customer and for every version of VP-ASP out there.
I am finishing the actual data conversion routine which would migrate the data from Access to SQL Server after these new SQL Tables have been created including any views or indexes. It is written entirely in ASP, with VB Scripting, the File System Object (FSO), the Dictionary Object, XML, DHTML, JavaScript right now and runs pretty quickly as you will see against a SQL Server 2008 Database just for the sake of an example.
It takes perhaps 15-20 seconds to reverse engineer almost 500 different database objects. There might be a total of over 2,000 columns involved in this example for the 170 tables and 270 indexes involved.
I have even come up with a way for you to run both VPASP systems in parallel using 2 different database connection files on the same server just to be sure that orders entered on the Access System and the SQL Server system produce the same results before actual cutover to production.
John (a/k/a The SQL Dude)
sales#designersyles.biz
(This is a VP-ASP Demo Site)
Here is a technique I've heard one developer speak on. This is if you really want something like a Client-Server application.
Create .mdb/.mde frontend files distributed to each user (You'll see why).
For every table they need to perform an CRUD, have a local copy in the file in #1.
The forms stay linked to the local tables.
Write VBA code to handle the CRUD from the local tables to the SQL Server database.
Reports can be based off of temp tables created from the SQL Server (Won't be able to create temp tables in mde file I don't think).
Once you decide how you want to do this with a single form, it is not too difficult to apply the same technique to the rest. The nice thing about working with the form on a local table is you can keep a lot of the existing functionality as the existing application (Which is why they used and continue to use Access I hope). You just need to address getting data back and forth to the SQL Server.
You can continue to have linked tables, and then gradually phase them out with this technique as time and performance needs dictate.
Since each user has their own local file, they can work on their local copy of the data. Only the minimum required to do their task should ever be copied locally. Example: if they are updating a single record, the table would only have that record. When a user adds a new record, you would notice that the ID field for the record is Null, so an insert statement is needed.
I guess the local table acts like a dataset in .NET? I'm sure in some way this is an imperfect analogy.
One of our clients is upgrading their servers because the old machines can't handle the load of the database anymore. They have been using sql 2000 for the last 6 years and the db has grown to hold a few GB of data.
Will it be worth upgrading to 2005 or 2008? What are the major benefits of the new versions compared to 2000?
In addition to the CLR integration mentioned by Galwegian, the main pluses for me are:
there is much better XML support in 2005
Common Table Expressons
Another difference to note is that instead of the DTS packages that you would have been used to Sql 2005 uses Integration Services, which while similar is a whole different ball game.
Depending on what edition of SQL Server you are using, SQL 2005 have less restrictive hardware limitations/caps than corresponding editions in SQL2k.
For example, SQL 2000 Standard Edition won't use more than 2Gb (in practice 1.7Gb) while SQL 2005 Standard Edition is not capped (allows up to OS max).
See:
http://msdn.microsoft.com/en-us/library/aa933149(SQL.80).aspx
...and...
http://www.microsoft.com/sqlserver/2005/en/us/compare-features.aspx
So: if you're running standard edition + your SQL Server 2000 instance currently uses ~1.6Gb RAM + your server has 3Gb or more physical RAM then it is probably worth upgrading just for the benefits increased memory usage brings... (more cached table data, indexes, plans etc)
I you are planing to upgrade from SqlServer 2000 I would skip 2005 and go directly to SqlServer 2008
It has all the features of 2005 plus some extras (for example an option to pass a table variable as a parameter to stored procedure, new date types, spatial data handling,etc.)
You can refer to Advantages of MS SQL Server 2008 over MS SQL Server 2005 question for the comprehensive list of features
EDIT
I can see that the question has been updated and now SqlServer 2008 is included in the question.
MS SQL 2005 and 2008 have a lot of hyped technologies, one of them is the ability to stuff CLR code into Stored Procedures. DON'T DO THIS!
Another "feature" is the ability to expose your database as WebServices, yet again; DON'T DO THIS!
A third feature is the ability to use "notifications" from your database and into your application layer, yet again; DON'T DO THIS...!
You database is a bucket and it should "store data", period. A lot of the features Microsoft put into 2005 and 2008 I feel sure they did because they wanted to complicate the usage of O/RM libraries which abstracts away the actual database vendor so that people can change databases as they wish. Then by adding a lot of "stupid features" which goes against every single Best Practices we've learned about databases since the 70s they managed to create a new lock-in which removed the vendor locks by making people use stuff they really shouldn't use anyway...
A part from that there might be a lot of cool features in 2005 and 2008 (like one mentioned here; support!) and things like optimalizations, bugfixes and such. But be careful so you don't start using stuff that craps down your app and makes it impossible to use best practices and locks you in... :(
The main benefit is CLR integration to be honest - it allows you much more flexibility in the way you code your database, giving you the option of including procedural C# or VB.NET in your procedures instead of set-based T-SQL.
There are some new features that are useful, like service broker for example, but in performance terms you aren't going to see huge improvements in moving from 2000 to 2005. You would be much better off a) tuning your DB and b) investing in new hardware.
I think that SQL Server 2000 is no more supported by Microsoft. If I'm wrong, it will be soon...
Separation of users and schemas is another goodie. In SQL 2005, if you want schema separation by logical/functional area or similar rather than by user in your database, you can create schemas such as "hr", "sales", "accounting", "production" and then create user tables under the respective schemas.
In SQL 2000, the schema name was identical to the table owner/creator.
Online index rebuilds are a nice feature to have. I think it might only be an option in Enterprise edition though.