Power Pivot Principles: The A to Z of DAX Functions – INFO.EXTENDEDPROPERTIES

In our long-established Power Pivot Principles articles, we continue our series on the A to Z of Data Analysis eXpression (DAX) functions.  This week, we look at INFO.EXTENDEDPROPERTIES.

The INFO.EXTENDEDPROPERTIES function

Dynamic Management Views (DMVs) are specialised queries provided by SQL Server Analysis Services (SSAS), Azure Analysis Services (AAS), and Power BI that offer an administrative view into the internal state of these systems.  DMVs are used to retrieve metadata, monitor health and performance, and diagnose problems within the database or data model.  They serve as a powerful tool for administrators and developers to gain insights into the workings of the database engine and the tabular data model, covering aspects like performance metrics, configuration settings and the structure of database objects.

The $System schema DMVs in SQL Server Analysis Services (SSAS), Azure Analysis Services (AAS), and Power BI are categorised into four [4] types, each serving specific purposes:

• DISCOVER: requires admin privileges and provides information about the model, including details on connected sessions and environment configuration
• DMSCHEMA: focused on data mining, offering insights for predictive analytics and pattern recognition, mainly used in SSAS/AAS
• MDSCHEMA: targets multidimensional models, delivering metadata and structure from an MDX perspective, relevant for OLAP cubes and dimensions
• TMSCHEMA: designed for tabular models, it provides detailed metadata about tables, columns, measures, etc., using Tabular Model Scripting Language (TMSL) information, crucial for Power BI and tabular SSAS/AAS models.

In the past, if we wanted to query those $System schema DMVs we used external tools like Tabular Editors or DAX Studio to query them:

Now, we just need to write a simple DAX syntax to query those TMSCHEMA directly in DAX query view.  In this instance, we are using INFO.EXTENDEDPROPERTIES function to query the TMSCHEMA_EXTENDED_PROPERTIES.

The INFO.EXTENDEDPROPERTIES function is one of the system functions.  It employs the following syntax:

This function has no parameters.

Based upon the ‘[MS-SSAS]: SQL Server Analysis Services Protocol’ from Microsoft (which you may access here), the ExtendedProperty objects represent one or more application-specific name/value pairs for the parent object.  The Analysis Services server does not interpret the ExtendedProperty objects.  An ExtendedProperty object requires compatibility level 1400 or higher.  The ExtendedProperty object has the following properties.  Possible logical metadata objects for which ExtendedProperty is a child object are listed for the ObjectType property.

We can write this INFO.EXTENDEDPROPERTIES function on DAX query view to get the same information on the TMSCHEMA_EXTENDED_PROPERTIES:

It will query $SYSTEM.TMSCHEMA_EXTENDED_PROPERTIES and return an entire table with seven [7] columns:

• ID: this is a reference to the object
• ObjectID: this is an ID-based reference to the object
• ObjectType: this represents the data type of the object that is specified by ObjectID.  The possible vales are as follows:
• TM_TYPEID_Model (1)
• TM_TYPEID_DataSource (2)
• TM_TYPEID_Table (3)
• TM_TYPEID_Column (4)
• TM_TYPEID_AttributeHierarchy (5)
• TM_TYPEID_Partition (6)
• TM_TYPEID_Relationship (7)
• TM_TYPEID_Measure (8)
• TM_TYPEID_Hierarchy (9)
• TM_TYPEID_Level (10)
• TM_TYPEID_KPI (12)
• TM_TYPEID_Culture (13)
• TM_TYPEID_LinguisticMetadata (15)
• TM_TYPEID_Perspective (29)
• TM_TYPEID_PerspectiveTable (30)
• TM_TYPEID_PerspectiveColumn (31)
• TM_TYPEID_PerspectiveHierarchy (32)
• TM_TYPEID_PerspectiveMeasure (33)
• TM_TYPEID_Role (34)
• TM_TYPEID_RoleMembership (35)
• TM_TYPEID_TablePermission (36)
• TM_TYPEID_Variation (37)
• TM_TYPEID_Expression (41)
• TM_TYPEID_ColumnPermission (42)
• Name:  this is the name of the object
• Type: this is a value that provides information about the format of the value.  the possible values are as follows:
• String (0) – The value is a raw string without specific formatting
• Json (1) – The value is a JSON object
• Value: this is the value of ExtendedProperty
• ModifiedTime: this is the time that the object was last modified.

It should be noted that:

• it is used for querying the DMV (Dynamic Management Views) from the $System schema
• sometimes querying DMVs may fail if we do not have the appropriate permission.

Come back next week for our next post on Power Pivot in the Blog section.  In the meantime, please remember we have training in Power Pivot which you can find out more about here.  If you wish to catch up on past articles in the meantime, you can find all of our Past Power Pivot blogs here.