When Microsoft designed the Data Import Export Framework in AX2012 it provided some entities out of the box. In many scenarios you will be missing an entity. You can create your own entities in the development environment from scratch or you can use the wizard which will create the basic objects required for your new entity. Sometimes you might run into errors and you should start troubleshooting. This post will provide a walkthrough how to create an entity. When finished this entity has an error due to conversion of an enumeration field. A solution for this problem is also provided at the end of this blog.
Alright, a question for you guys. Have you ever heard of a SLA (service level agreement)? It’s the thing you agree on with your implementing partner after they have successfully implemented your new system. If you’ve come so far, congratulations. You’ve probably managed to overcome a lot of hiccups along the way but you made it, you now have a system that meets all your needs.
But your journey is not over yet. There has to be maintenance in order to keep the system fresh. Because of this you come to a maintenance agreement with your partner. Of course not just for AX but also for BizTalk, SQL, BI and all the other stuff. Now you can feel confident that along the way your system will always be up to date and it gives you the ultimate guarantee nothing can go wrong anymore, but does it? What does it guarantee? And what is the cost of this guarantee?
What you agreed on in SLA
Most service level agreements -SLA- probably contain nothing more than the following things:
- The right to have your system updated.
- A promise that they will help you with it and a discount on the hours spent helping you.
- Technical support
- They may even include a number of free minutes, you can use to call someone at a helpdesk. What you don’t know is that while you’re on hold and listen to the beautiful tune, your minutes run out.
What you actually wanted
You just wanted a system that runs smoothly and makes you a satisfied user. But your partner will push you to do all the updates because otherwise everything will inevitably go wrong. This is kind of comparable to the millennium madness. Remember? So many people were convinced that all the electronic devices were going to crash, some even made a lot of money because of others` ignorance, and eventually, when the clock ticked 12, nothing happened. Everything was working as it was supposed to be. With SLA’s it’s kind of the same. They just want you to be scared enough to spent a lot of money on something that is not always necessary, the same goes for updates.
But what are your options? Can you just do nothing? Or is there a way to avoid all these costs and headaches? I will let you know in the next blog 😉 but meanwhile subscribe to our newsletter so you can receive our latest blogs straight to your inbox.
What do you think about SLA`s and updates? Share your thoughts and if you liked this post, please share it.
Are SQL Window Functions new?
Since 2003 in the SQL ANSI/ISO standard and extended in 2008. Microsoft implemented the first window functions in their SQL Server 2005 version (known as OVER clause) and extended them in the following versions.
So to be short no they are not new for the ANSI/ISO standard and for Microsoft SQL Server window functions exist for a few version now. Within in Dynamics Ax we use X++ which is translated by the Dynamics Ax Kernel to T-SQL to make the database return a result set. This makes us depended of the implementation of X++, which in Dynamics Ax 2012 doesn’t support window functions for select statements etc. But I can show you a way on how to use them in AX 2012 and up.
What are SQL Window Functions?
Let me show you with an example. As this is a blogpost for Dynamics Ax minded people let us use the SalesLine table.
If you want to select a few fields of this table, you would write something like the following (in SQL and X++):
If you would like to see the total amount of the salesorder in the same result set you would need to do a “GROUP BY”:
in X++ you would do something like this:
But it will send a statement for each salesline to the database.
A better way to do this in Ax would actual be:
- Create a Query object for the ‘select sum(LineAmount), SalesId from salesLine’ bit.
- Put that Query in a View.
- Now create a new Query with in the datasource the SalesLine and join it with the View.
Now let’s make it even more interesting. I would like a statement to get a resultset with the following columns:
- the SalesId, ItemId, SalesCategory, CustAccount, LineAmount.
- the total amount of the salesorder.
- the avg LineAmount of the customer in the same category.
- the LineAmount of the last time this customer ordered this item.
- running total of this customer.
And here we are, our first window functions. They are called window functions because they put a window (subset) over the rows you get out of your FROM clause.
The <window function> part can be: Ranking functions, Aggregate functions or Analytic functions.
After the OVER keyword you can limit the size of the window:
- OVER() isn’t limiting at all so all rows are considered.
- OVER (PARTITION BY X) means limit the window to al rows that have matching values in Column X in current Row.
- OVER (ORDER BY) changes the sort order in the window. (Can be nice if you use RANK or ROW_NUMBER window functions)
- OVER( ROWS BETWEEN … AND …) limits the window to the rows between the given criteria seen from current row.
How to use these powerful window functions in Dynamics AX?
As I mentioned before X++ isn’t a real options. But in the View objects in the AOT there is a little gem that we can polish for our purpose.
- Create a Query for the SELECT SALESID, ITEMID, SALESCATEGORY, CUSTACCOUNT, LINEAMOUNT FROM SALESLINE part.
- Use this Query in a new View.
- Create a method on the View with the following code:
- Now right click on the ‘fields’ branch of the view choose NewReal computed column.
- Give the new field a nicer name and set the name of the method in the ‘viewmethod’ property.
- Save and synchronise the view.
Now what did we just do?
We changed the create statement of the view to include ‘SUM(LINEAMOUNT) OVER (PARTITION BY SALESID)’ as a column. By synchronizing we created a view in SQL Server that contains the window functions we want to.
Could we use this for other things then window functions?
Yes you can use all possibilities of the T-SQL language here. But remember you are changing the Select clause of the view here. Putting a select statement in here (or a stored procedure) will for sure make the view run a long time as every row will trigger a separate statement. But a scalar value function can be very valuable sometimes (like ISNULL()).
All code samples, walkthroughs and other instructions are provided as-is. Use any and all information provided in this blog at your own risk. It is never advised to import or write code in a production environment without rigorous testing in a test or development environment.
All opinions expressed in this blog are solely my own and do not necessarily reflect the opinions of my employer.
The names of actual companies and products mentioned in this blog may be the trademarks of their respective owners.
Microsoft and Dynamics AX are registered trademarks of Microsoft Corporation in the United States and other countries.
Let us have a look at SQL Compression, with this I mean Data compression not the backup compression which is also available in SQL Server nowadays.
This feature can be implemented in SQL Server without affecting the programs that use the database, because it is only used inside of SQL Server and the way it stores its data. Which means that SQL Server will compress the data as it is entered in the database. SQL Server will use the data compressed for all it’s internal operations, and YES the data is still compressed when it is put into memory resulting in more rows in the same memory space which increases performance. Then if the data is send to the application which requested the data, SQL Server will decompress it. Compressing and decompressing data is a CPU intensive task, which leads to an increase of 15% on CPU usage. The save on storage and the increase of the number of rows on a page and the increase of the number of rows in the memory banks will certainly outweigh the increase in CPU usage.
SQL Server versions with Compression
Data compression became available in SQL 2008 and was further improved in SQL 2008 R2 after which it is continued in all version including the latest SQL 2016. Because it is an advanced feature it is only available in Enterprise Editions of SQL. (And Developer Edition which isn’t to be used in a production environment).
Types of compression
There are 2 types of compression available in SQL Server. Row compression and Page compression the latter implements the first and more, but let me explain both of them to you.
This type of compression does what it says it compresses the row of data in an index/table. And will do this in several ways, which I’ll discuss below.
Metadata is information about the columns for some data types the meta data is larger then the actual data type (for example Bit).
Delete not used space in fixed size datatypes
Row compression will delete the space that isn’t used in fixed sized strings, which means that a CHAR(10) can become a CHAR(1) if only 1 character is in it. Remember it is ROW compression so it will determine the actual used space per value not per column over the entire table/index. Unfortunately Dynamics Ax doesn’t use fixed sized string (it uses NVARCHAR instead), so we cannot gain anything by this.
Fortunately SQL Server also sees numeric values as (a form of) fixed sized, and it will delete leading and/or trailing zero’s if there are any. In Dynamics Ax all amounts are stored as NUMERIC(32,16) but if the actual amount is $1,95 if compression is applied it will only store the 1,95 removing the space it would normally store additionally to make it (32,16). The same is applied to integers and BIGINT, and Date and Datetime are converted to integers which also saves on storage.
Not effected by row compression are memo fields (NVARCHAR(MAX)), Images (VARBINARY), GUID (UNIQUEIDENTIFIER).
Standard Compression Scheme for Unicode
SQL Server also uses an implementation of the Standard Compression Scheme for Unicode (SCSU) algorithm to compress Unicode values. Because SQL Server stores data as 2 bytes regardless of the language of the data. Depending on the language of your data you can save up to 50% on the storage of all nvarchar() and nchar() datatype columns. Languages with the highest compression rate are: Western European languages as English, Dutch, German, French, Spanish etc. but also Hindi. On the lower end we find languages with more characters like Japanese which has a compression rate of 15%.
Dynamics Ax uses Unicode for all strings stored in its database.. I’ll repeat that ALL strings. So if you’re language is for example English this means that ALL your stored text can be stared in half the space it is using right now. Great news I would say.
Page compression uses Row compression as mentioned before, but it also uses the following to techniques.
SQL Server will determine per column a prefix value that is used (fully or partially) by the most rows. After determining this SQL places this value in the header and references to it (or part of it) in the row value. Which is best visualized by these images of Microsoft MSDN:
Yes you can do all that… Or use below script to do all the hard work for you and even deliver you the scripts to update the indexes: