Validation can be one of four options.

1. None (My personal favorate especially for sample code)
2. Empty
3. Well_Formed_XML
4. Valid_XML With Schema Collection

1 and 2 are pretty straight forward.  None = No validation is done.  Empty = The message must be empty.  Well_Formed_XML requires that the XML be a valid XML document.  The fourth option requires that not only the XML be valid, but that it fits within a pre-existing XML schema collection (an XSD which has been loaded into the SQL Server).

The syntax to create a Message Type is pretty basic.

CREATE MESSAGE TYPE [MessageTypeName]
VALIDATION = NONE

That’s it.  If you need to change the schema use the AUTHORIZATION clause to set the owner of the object.

When using the validation of NONE it is up to the receiving code or application to verify that the data within the message exists and is valid.

Denny

Hopefully when I get back I’ll have all sorts of new storage tips and tricks to share with everyone.

If anyone else if brave enough to attend let me know here.  Maybe we can meet up at one of the events.

Denny

These days space isn’t the issue.  Storage is very cheep these days, and if you have the money you can get absolutely massive amounts of storage.  1 TB hard drives are easily found, and when you start talking about RAIDing drives together the storage limits start to become just insane.  100 TB of storage just isn’t what it used to be.

The problem now becomes that with so much data for the database platform to search through we need to make sure that the indexes which SQL Server is searching as as small as possible so that we can get those indexes read from the disk and into memory as quickly as possible.

Say we have an Employee table which looks like this.

CREATE TABLE Employee
(EmployeeId INT,
FirstName NVARCHAR(50),
LastName NVARCHAR(50),
Department NVARCHAR(100),
Manager_First_Name NVARCHAR(50),
Manager_Last_Name NVARCHAR(50),
Location NVARCHAR(50),
Active VARCHAR(5))

Now this table is clearly not setup as a normalized table.  We are assuming that this table has best case indexing.  If we have 1000 employees records and we are going to search the Department column the index must be read from disk.  Now assuming that the department names are nice long bureaucratic names which average 30 characters each we have about 30000 bytes (more if you take the fill factor into account) which needs to be read from the disk.  Now if we had a relational version of the table.

CREATE TABLE Employee
(EmployeeId INT,
FirstName NVARCHAR(50),
LastName NVARCHAR(50),
DepartmentID INT,
ManagerEmployeeID INT,
LocationId INT,
Active BIT)

When we search the Employee table we now are only loading an integer value from the disk into memory. This means that we only have to load 8000 bytes of data from the disk into memory. Now knowing that SQL Server reads data from the disk in 8k blocks even with a 50% fill factor the index only takes 2 blocks on the disk and can then be completed in two read operations to the disk. Now our original table with no fill factor will require 30 data pages (20.297 to be specific), about 60 if we use the same fill factor.

With tables of this size this isn’t much. But as your database grows the number of additional data pages which would have to be read for a simple search of the table grows exponentially.

Denny

 While the configuration can be a daunting task, once the service broker is setup it is a very solid system which can handle a large message load.

The Service Broker give you guaranteed delivery order, with single processing of messages always in the order received.  Messages can be processed on demand (you write software which queries the service broker on a schedule) or automatically via the queue activation.

Check back for information about all the various service broker object an how to configure each of them.

Denny

You can download or view the video from here.

I’ve got to tell you, I had an absolute blast recording the video.

Denny

I won’t be speaking there until December 9, 2008 (it’s amazing just how far in advance some of this stuff gets scheduled).

I’ll be giving two presentations at the meeting.  The first will be the ever popular Query Tuning, and the second will be a talk on the SQL Server 2008 Resource Governor.  The address and directions to the meeting can be found on the IE .NET User Group web site.  If you are going to attend there meetings they have an RSVP link on the site.

I’ll post about this meeting again closer to the meeting.

Denny

 Starting in SQL Server 2005 you now have the ability to query the system catalog and see what query plans are stored in the cache, as well as the queries which trigger that plan to be used, as well as how many times that cached plan has been used.

The first DMV to look at is sys.dm_exec_cached_plans.  This DMV gives you the size of the plan, the handle of the plan (which is binary), and the number of times the plan has been used.

The next DMV to look at is sys.dm_exec_requests.  This DMV gives you the currently running processes, wait information, all the session settings for the processes, etc.  It also includes the handle for all the plans which are currently being run.  If you join this sys.dm_exec_requests to sys.dm_exec_cached_plans you can see exactly which processes are using which plans.  Because this shows you the spid (the session_id column) and the plan_handle you can see what users are running which commands.

The next object is a system table function called sys.dm_exec_query_plan.  This function accepts a single input parameter of a plan handle.  There are several columns in the output, the most important of which is the query_plan.  This is the actual xml plan which is stored in the SQL Server.

The last object we’ll be looking at is the sys.dm_exec_plan_attributes table function.  This function also accepts a single input parameter of a plan handle.  This function returns the various session settings which were in place when the plan was created.  This is important information to have when working with query plans, as changing a single ANSI connection setting will force SQL to create a new execution plan.

Don’t forget how to view the XML execution plan in the UI.

Denny

However there is a much easier way.  Microsoft has included the system extended stored procedure xp_fixeddrives.  It returns the all the fixed drives and the amount of free space in megs.

Denny

This same information appears to hold true for SQL Sever 2008 (so far at least).

Denny

DELETE FROM Employee
WHERE EmployeeId = 4

You can also JOIN to a table when you delete data from a table which allows you to use the second table within the filter.  This requires a slightly different syntax than your normal DELETE syntax.

DELETE e
FROM Employee e
JOIN Department ON Employee.DepartmentId = Department.DepartmentId
  AND Department.DepartmentName = ‘Sales’

As you can see you need to set an alias for the table you are deleting from, and put that alias between the DELETE and FROM words.

Denny

P.S. Sorry this didn’t come up sooner, I could have sworn that I wrote it and published it back when I started the series.