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–MDL009) + 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

• semantic-model — Model design, build, and 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