dax

name	dax
version	26.25
description	DAX performance optimization for semantic models. Automatically invoke when the user asks to "optimize DAX", "fix slow DAX", "DAX performance", "tune a measure", "debug a measure", "DAX anti-patterns", or mentions slow queries, server timings, or DAX authoring.

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 Tabular Editor CLI te query (see the te-cli skill) first; as an alternative, the connect-pbid skill covers FE/SE timing (performance-profiling.md) and intermediate result inspection (evaluateandlog-debugging.md).
• Remote models (Fabric Service / XMLA): Run DAX with the Tabular Editor CLI te query (-s <workspace> -d <model>) against the workspace XMLA endpoint; see the te-cli skill (tabular-editor plugin).
• Power BI Modeling MCP: also available for trace and query if you prefer an MCP tool; reach for it after the options above.

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