What is xml.mdx?

xml.mdx is a file type that stores MDX (Multidimensional Expressions) queries inside an XML wrapper. MDX is a language used to ask questions of OLAP (Online Analytical Processing) cubes - the kind of data structures that power complex business‑intelligence reports. By putting the MDX code in XML, the file becomes both human‑readable and easy for programs to parse, share, and version‑control.

Let's break it down

  • XML - Extensible Markup Language, a text format that uses tags (like <tag>) to describe data and its hierarchy. It’s widely used for data exchange because it’s both machine‑readable and fairly easy for people to read.
  • MDX - A query language similar to SQL but designed for multidimensional data (cubes). It lets you retrieve, filter, and calculate values across dimensions such as time, geography, product, etc.
  • .xml.mdx file - Think of it as a small XML document whose main content is an MDX script. The XML part may include metadata (author, description, version) while the MDX part holds the actual query that will run against an OLAP cube.

Why does it matter?

  • Portability - XML is a universal format, so an xml.mdx file can be moved between different tools, platforms, or teams without losing structure.
  • Version control friendly - Because it’s plain text, you can store xml.mdx files in Git or other source‑control systems and track changes line by line.
  • Self‑documenting - The XML wrapper can hold comments, documentation, and parameters, making the query easier to understand and reuse.
  • Automation - Scripts and applications can read the XML, extract the MDX, and run it automatically, enabling scheduled reports or data pipelines.

Where is it used?

  • Microsoft Analysis Services - When developers export or import MDX scripts, they often use the xml.mdx format.
  • Business‑intelligence tools - Products like Power BI, Tableau (via extensions), or custom reporting platforms may accept xml.mdx files for custom cube queries.
  • Data‑warehouse projects - Teams that build and maintain OLAP cubes use xml.mdx to share query logic between developers, analysts, and QA testers.
  • Learning environments - Training courses on MDX sometimes provide sample xml.mdx files so students can see both the query and its surrounding documentation.

Good things about it

  • Readability - Both the XML tags and the MDX code are plain text, making it easy to open in any editor.
  • Metadata support - You can embed author, purpose, parameters, and change‑log directly in the file.
  • Tool compatibility - Most OLAP‑related tools understand XML, so they can import or export xml.mdx without conversion.
  • Safe for source control - No binary blobs; diffs are clear and merges are manageable.
  • Extensible - If you need extra information (e.g., security tags or execution hints), you can add custom XML elements without breaking the MDX part.

Not-so-good things

  • Verbosity - XML adds a lot of extra tags, so the file can become larger and harder to skim compared to a plain .mdx script.
  • Learning curve - Beginners must understand two syntaxes (XML and MDX) at once, which can be confusing.
  • Tool dependence - Some lightweight MDX editors only accept plain .mdx files, requiring conversion or extra steps.
  • Performance overhead - When programs parse the XML wrapper before extracting the MDX, there’s a small processing cost, noticeable only in very large batch operations.
  • Potential for mismatched schemas - If the XML metadata doesn’t match the actual MDX (e.g., wrong parameter names), it can cause runtime errors that are hard to trace.