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Semantic layer overview

Who can do this

Administrators with the Semantic models permission.

The semantic layer is the governed description of your data. Instead of everyone writing their own SQL — with their own subtly different definitions of "revenue" — administrators describe the data once, and every chart, table, card, and Axi answer compiles against those shared definitions.

Semantic models​

Each connection has a set of semantic models, typically one per table. A model gathers everything Axiome knows about that table:

  • Overview — a display name and a description ("What does one row of this model represent?"). The description is surfaced in the catalog and used to ground Axi, so a good description directly improves AI answers.
  • Keys — primary and foreign keys, declaring how models join.
  • Dimensions — attributes to group and filter by.
  • Measures — aggregations over rows.
  • Metrics — curated business definitions built on measures.

Models are managed in Settings → Admin → Semantic models. That page covers one connection at a time — pick which one from the selector at the top.

Teams that maintain a dbt project don't have to write these definitions by hand — see Import from dbt.

The Semantic models page: model list on the left, the Overview tab open with a model's description filled in.

Generated, edited, custom​

When a connection is created (and whenever you click Refresh schema), Axiome introspects the database and generates a baseline model for each table: dimensions and measures inferred from column names and types. Each element carries a provenance badge:

  • Generated — produced from the schema, untouched.
  • Edited — generated, then customized (the overridden fields are listed).
  • Custom — created by an administrator from scratch.

Metrics are always curated — Axiome never invents business definitions for you.

You can Reset to generated at any time to discard all customizations of a model and fall back to the baseline. This cannot be undone.

Refreshing the schema​

When your database schema changes, click Refresh schema. Axiome re-introspects the source and shows a per-model report: New, Removed, Changed, or Unchanged columns. Your customizations are kept; a dimension whose underlying column disappeared is flagged as orphaned so you can fix or remove it.

Concurrent editing​

Model editing is safe for teams: if someone else saved the same model while you were editing, Axiome detects the conflict and asks you to reload before re-applying your changes — no silent overwrites.

Why it matters for Axi​

Axi plans its queries against the semantic layer: model descriptions, dimension and measure names, metric definitions, and declared join paths. A well-curated layer is the single highest-leverage thing you can do to make Axi's answers accurate. Hide internal columns, describe your models, and define your key metrics.