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

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.FUNCTIONS.

The INFO.FUNCTIONS 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 MDSCHEMA directly in DAX query view.  In this instance, we are using INFO.FUNCTIONS function to query the MDSCHEMA_FUNCTIONS.

The INFO.FUNCTIONS 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 MDSCHEMA_FUNCTIONS  schema rowset returns information about the functions that are currently available for use in the DAX and MDX languages.

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

It will query $SYSTEM.MDSCHEMA_FUNCTIONS and return an entire table with 15 columns:

• FUNCTION_NAME: this is the name of the function
• DESCRIPTION: this is a description of the function
• PARAMETER_LIST: this is a description the parameters accepted by the function
• RETURN_TYPE: this is the OLE DB data type that is returned by the function
• ORIGIN: the possible values are as follows:
• (0x1) MSOLAP
• (0x2) UDF
• (0x3) RELATIONAL
• (0x4) SCALAR
• INTERFACE_NAME: this is a logical classification of the type of function.  For example:
• DATETIME
• LOGICAL
• FILTER
• LIBRARY_NAME: this is the library that implements the function
• DLL_NAME: this is unused
• HELP_FILE: this is unused
• HELP_CONTEXT: this is unused
• OBJECT: this is the type of object on which this function can be called.  For example, the Children MDX function can be called on a Member object
• CAPTION: this is the caption of the function
• PARAMETERINFO: this is the parameters that can be provided to this function
• DIRECTQUERY_PUSHABLE: this is a bitmask that indicates the scenarios in which this function can be used when the model is in DirectQuery mode.  The possible values are as follows:
• (0x1) MEASURE: This function can be used in measure expressions
• (0x2) CALCCOL: This function can be used in calculated column expressions
• VISUAL_CALCULATIONS_INFO: this is not mentioned in the current MS-SSAS (14 May 2024) document.

Here are a few remarks about function come with INFO prefix:

• 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.