DAX

Skills and references for writing, debugging, and optimizing DAX in semantic models.

Optimization

For systematic DAX query performance optimization, read the workflow reference first:

references/dax-performance-optimization.md

— Tiered framework (4 tiers), phased workflow, decision guide, and error handling.

Detailed reference files (progressive disclosure — consult as directed by the workflow):

• references/engine-internals.md

  — FE/SE architecture, xmSQL, compression/segments, SE fusion, trace diagnostics

• references/dax-patterns.md

  — Tier 1 DAX patterns (DAX001–DAX021) + Tier 2 query structure (QRY001–QRY004)

• references/model-optimization.md

  — Tier 3 model patterns (MDL001–MDL010) + Tier 4 Direct Lake (DL001–DL002)

Trace capture and performance profiling:

• Local models (Power BI Desktop): Use the

  connect-pbid

  skill — specifically

  performance-profiling.md

  for FE/SE timing and

  evaluateandlog-debugging.md

  for intermediate result inspection.
• Remote models (Fabric Service / XMLA): Use the

  powerbi-modeling-mcp

  VS Code extension for trace and query operations. Install:

  code --install-extension analysis-services.powerbi-modeling-mcp

Related Skills

• review-semantic-model

  — Model auditing including DAX anti-patterns and best practices

• connect-pbid

  (pbi-desktop plugin) — Trace capture, performance profiling, EVALUATEANDLOG debugging

• lineage-analysis

  — Impact analysis before model changes