Omni Model Builder

Create and modify Omni's semantic model through the YAML API — views, topics, dimensions, measures, relationships, and query views.

Tip: Always use omni-model-explorer first to understand the existing model.

Prerequisites

# Verify the Omni CLI is installed — if not, ask the user to install it
# See: https://github.com/exploreomni/cli#readme
command -v omni >/dev/null || echo "ERROR: Omni CLI is not installed."

# Show available profiles and select the appropriate one
omni config show
# If multiple profiles exist, ask the user which to use, then switch:
omni config use <profile-name>

You need Modeler or Connection Admin permissions.

Tip: Use -o json to force structured output for programmatic parsing, or -o human for readable tables. The default is auto (human in a TTY, JSON when piped).

Omni's Layered Modeling Architecture

Omni uses a layered approach where each layer builds on top of the previous:

1. Schema Layer — Auto-generated from your database. Reflects tables, views, columns, and their types. Kept in sync via schema refresh.

2. Shared Model Layer — Your governed semantic model. Where you define dimensions, measures, joins, and topics that are reusable across the organization.

3. Workbook Model Layer — Ad hoc extensions within individual workbooks. Used for experimental fields before promotion to shared model.

4. Branch Layer — Intermediate development layer. Used when working in branches before merging changes to shared model.

Key concept: The schema layer is the foundation and source of truth for table/column structure. When your database schema changes (new tables, deleted columns, type changes), you refresh the schema to keep Omni in sync. All user-created content (dimensions, measures, relationships, topics) flows through the shared model layer.

Development workflow: When building or modifying the model, you work in branches (see "Safe Development Workflow" below). Branches are isolated copies where you can safely experiment before merging changes back to shared model. This skill covers creating and editing model definitions in both branches and shared models.

Determine SQL Dialect

Before writing any SQL expressions, confirm the dialect from the connection — don't guess from the connection name:

# 1. List models to find connectionId
omni models list

# 2. Look up the connection's dialect
omni connections list
# → find your connectionId and read the "dialect" field
# → e.g. "bigquery", "postgres", "snowflake", "databricks"

Use dialect-appropriate functions in your SQL (e.g. SAFE_DIVIDE for BigQuery, NULLIF(a/b) for Postgres/Snowflake).

Schema Refresh: Syncing with Database Changes

The schema layer is auto-generated from your database. When your database schema changes (new/deleted/renamed columns, type changes), refresh Omni's schema layer to stay in sync.

When to trigger:

• New tables added to your database
• Column added/renamed/deleted in existing tables
• Creating a new view from scratch and want auto-generated base dimensions
• Model is out of sync with database

What it does:

• Introspects your data warehouse
• Auto-generates base dimensions for all columns with correct types and timeframes
• Detects deletions and broken references
• Runs as a background job (can take several minutes)

Side effect: May auto-generate dimensions for columns you don't need. Suppress with hidden: true in your extension layer.

Trigger via API:

omni models refresh <modelId>

# With branch:
omni models refresh <modelId> --branch-id <branchId>

Requires Connection Admin permissions.

Discovering Commands

omni models --help              # List all model operations
omni models yaml-create --help  # Show flags for writing YAML

Safe Development Workflow

Always work in a branch. Never write directly to production.

Step 0: Create a Branch

omni models create-branch <modelId> --name "my-feature-branch"

The response model.id is your branchId — a UUID you'll pass to all subsequent API calls. To list existing branches at any time:

omni models list --include activeBranches

Git-connected models: If your model is connected to a git repo (omni models git-get <modelId> returns an sshUrl), merging an Omni branch will automatically commit the changes back to your git baseBranch. Choose one workflow and stick to it — either edit via the Omni branch API (then git pull to sync local files), or edit local files and push via git. Mixing both leads to conflicts.

Step 1: Write YAML to a Branch

omni models yaml-create <modelId> --body '{
  "fileName": "my_new_view.view",
  "yaml": "dimensions:\n  order_id:\n    primary_key: true\n  status:\n    label: Order Status\nmeasures:\n  count:\n    aggregate_type: count",
  "mode": "extension",
  "branchId": "{branchId}",
  "commitMessage": "Add my_new_view with status dimension and count measure"
}'

Note: The branchId parameter must be a UUID from the server (Step 0). Passing a string name instead will return 400 Bad Request: Unrecognized key: "branchName".

Step 2: Validate and Test

Every YAML write must be validated and tested before merging. Silent failures are common — a field can be syntactically valid YAML but produce wrong results or broken queries.

2a. Run model validation:

omni models validate <modelId> --branchid <branchId>

Check the response:

• If any issue has is_warning: false, it's an error — fix before proceeding
• Common errors: broken column references, duplicate field names, invalid SQL syntax, missing join paths
• If auto_fix is present, review the suggestion before applying

2b. Test new/modified fields with a query:

Run a query that exercises the fields you just created or modified:

Note: omni query run does not currently support branchId — queries always run against the production model. This means you can only fully test new fields after merging. Use model validation (2a) and field verification (2d) as your pre-merge safety net, and run query tests immediately after merging.

omni query run --body '{
  "query": {
    "modelId": "<modelId>",
    "table": "your_view",
    "fields": ["your_view.new_dimension", "your_view.new_measure"],
    "limit": 10,
    "join_paths_from_topic_name": "your_topic"
  }
}'

What to check:

• No error in response — if the query returns an error, the field SQL is broken (bad column reference, wrong aggregate, dialect mismatch)
• summary.row_count > 0 — confirms the field resolves to actual data
• Values look correct — spot-check that a sum isn't returning a count, that a boolean dimension returns true/false (not 0/1 unexpectedly), etc.
• Joins work — if your field references another view (e.g., ${users.id}), include fields from both views to confirm the join resolves

2c. If you modified a relationship or topic join, test the join path:

omni query run --body '{
  "query": {
    "modelId": "<modelId>",
    "table": "base_view",
    "fields": ["base_view.id", "joined_view.some_field"],
    "limit": 10,
    "join_paths_from_topic_name": "your_topic"
  }
}'

A working join returns rows with data from both views. A broken join returns an error or null values in the joined columns.

2d. Verify the field appears in the model:

# Check the topic to confirm new fields are listed
omni models get-topic <modelId> <topicName> --branch-id <branchId>

# Or read back the YAML you just wrote
omni models yaml-get <modelId> --filename your_view.view --branchid <branchId>

Confirm your new fields are listed in the response. If they're missing, the YAML write may have silently failed (e.g., wrong fileName, malformed YAML string) — or the view may live in an offloaded schema that yaml-get doesn't surface. See omni-model-explorer § Fallback: Expected View Missing from yaml-get for how to recover.

Step 3: Merge the Branch

Important: Always ask the user for confirmation before merging. Merging applies changes to the production model and cannot be easily undone. Only merge after validation and testing pass (Step 2).

omni models merge-branch <modelId> <branchName>

If git with required PRs is configured, merge through your git workflow instead.

After merging, run one final validation against the production model to confirm the merge didn't introduce conflicts:

omni models validate <modelId>

YAML File Types

Type	Extension	Purpose
View	.view	Dimensions, measures, filters for a table
Topic	.topic	Joins views into a queryable unit
Relationships	(special)	Global join definitions

Write with mode: "extension" (shared model layer). To delete a file, send empty yaml.

Writing Views

Every view that participates in joins MUST have a real primary_key: true dimension. Without a genuine row-unique primary key, queries that join to this view can produce fanout errors or incorrect aggregations. Use the table's natural unique identifier (e.g., id, order_id, user_id). If no single column is unique, build a composite key from row-level columns that are jointly unique, for example sql: ${order_id} || '-' || ${line_number}. If you cannot define a row-unique expression, do not mark a dimension as primary_key: true yet; fix the grain first or avoid joining the view until a real key exists.

Basic View

dimensions:
  order_id:
    primary_key: true
  status:
    label: Order Status
  created_at:
    label: Created Date
measures:
  count:
    aggregate_type: count
  total_revenue:
    sql: ${sale_price}
    aggregate_type: sum
    format: currency_2

Understanding Schema Layer vs Extension Layer

When you create a view, Omni separates schema (database structure) from model (your business logic):

• Schema layer: Auto-generated base dimensions, one per column. Types come from the database. Read-only, synced via schema refresh.
• Extension layer: Your custom YAML. Can override base dimensions, add new dimensions/measures, hide columns, add business logic.

When both layers exist for a field with the same name, your extension definition wins but type information comes from the schema layer.

Example: Table has columns created_at (DATE) and revenue (NUMERIC).

# Schema layer (auto-generated)
dimensions:
  created_at: {}  # type: DATE, auto-generates timeframes
  revenue: {}     # type: NUMERIC

# Extension layer (your YAML)
dimensions:
  created_at:
    label: "Order Created"
    description: "When the order was placed"

  revenue:
    hidden: true  # Hide the raw column

measures:
  total_revenue:
    sql: SUM(${revenue})
    aggregate_type: sum
    format: currency_2

Result: created_at inherits its type from schema layer (DATE with automatic week/month/year granularities) but gets your label. The raw revenue column is hidden, only exposed through the total_revenue measure.

Key insight: If your extension layer defines a dimension but there's no schema layer base dimension to provide type information, Omni can't infer granularities or types. Solution: trigger schema refresh to auto-generate the schema layer (see "Schema Refresh" section above).

Dimension Parameters

See references/modelParameters.md for the complete list of 35+ dimension parameters, format values, and timeframes.

Most common parameters:

• sql — SQL expression using ${field_name} references
• label — display name · description — help text (also used by Blobby)
• primary_key: true — unique key (critical for aggregations)
• hidden: true — hides from picker, still usable in SQL
• format — number_2, currency_2, percent_2, id
• group_label — groups fields in the picker
• synonyms — alternative names for AI matching (e.g., [client, account, buyer])

Measure Parameters

See references/modelParameters.md for the complete list of 24+ measure parameters and all 13 aggregate types.

Measure filters restrict rows before aggregation:

measures:
  completed_orders:
    aggregate_type: count
    filters:
      status:
        is: complete
  california_revenue:
    sql: ${sale_price}
    aggregate_type: sum
    filters:
      state:
        is: California

Filter conditions: is, is_not, greater_than, less_than, contains, starts_with, ends_with

Writing Topics

See Topics setup for complete YAML examples with joins, fields, and ai_context, and Topic parameters for all available options.

Key topic elements:

• base_view — the primary view for this topic
• joins — nested structure for join chains (e.g., users: {} or inventory_items: { products: {} })
• ai_context — guides Blobby's field mapping (e.g., "Map 'revenue' → total_revenue")
• default_filters — applied to all queries unless removed
• always_where_sql — non-removable filters
• fields — field curation: [order_items.*, users.name, -users.internal_id]

Writing Relationships

- join_from_view: order_items
  join_to_view: users
  on_sql: ${order_items.user_id} = ${users.id}
  relationship_type: many_to_one
  join_type: always_left

Type	When to Use
many_to_one	Orders → Users
one_to_many	Users → Orders
one_to_one	Users → User Settings
many_to_many	Tags ↔ Products (rare)

Getting relationship_type right prevents fanout and symmetric aggregate errors.

Query Views

Virtual tables defined by a saved query. Like regular views, query views must include a primary_key: true dimension to be joinable:

schema: PUBLIC
query:
  fields:
    order_items.user_id: user_id
    order_items.count: order_count
    order_items.total_revenue: lifetime_value
  base_view: order_items
  topic: order_items

dimensions:
  user_id:
    primary_key: true
  order_count: {}
  lifetime_value:
    format: currency_2

Or with raw SQL:

schema: PUBLIC
sql: |
  SELECT user_id, COUNT(*) as order_count, SUM(sale_price) as lifetime_value
  FROM order_items GROUP BY 1

Common Validation Errors

Error	Fix
"No view X"	Check view name spelling
"No join path from X to Y"	Add a relationship
"Duplicate field name"	Remove duplicate or rename (or suppress with hidden: true if one is auto-generated)
"Invalid YAML syntax"	Check indentation (2 spaces, no tabs)
Fanout / incorrect aggregations on joins	Add primary_key: true to the joined view — every view that participates in a join must have a primary key
Column reference error (e.g., "Column X not found")	Check that the table exists and your Omni connection has access

Troubleshooting: Model Out of Sync with Database

If your model doesn't reflect the database (missing columns, broken references, wrong types), trigger a schema refresh (see "Schema Refresh" section above). Then validate:

omni models validate <modelId>

Common issues and fixes:

Issue	Cause	Fix
Broken column references	Column no longer exists in database	Remove or update the sql reference
Field name collision	Auto-generated dimension conflicts with your measure	Suppress with hidden: true or rename
Unknown field types	Type info not available from schema	Verify column exists and connection has access
Missing tables	Table not in schema after refresh	Verify table exists and connection includes its database/schema

Docs Reference

• Model YAML API · Views · Topics · Dimensions · Measures · Relationships · Query Views · Branch Mode

Related Skills

• omni-model-explorer — understand the model before modifying
• omni-ai-optimizer — add AI context after building topics
• omni-query — test new fields