fyrnheim 0.4.2

Define typed Python entities, generate transformations, run anywhere. A dbt alternative built on Pydantic + Ibis.

Fyrnheim

Activities-first data transformation framework.

Built on Pydantic + Ibis. Define typed sources, detect business events from state changes, resolve identities across systems, and project entity models -- all in Python.

Install

pip install fyrnheim[duckdb]

Quick Start

1. Create a project:

fyr init myproject && cd myproject

2. Define your pipeline in entities/customers.py:

from fyrnheim import (
    StateSource, ActivityDefinition, RowAppeared, FieldChanged,
    IdentityGraph, IdentitySource, EntityModel, StateField,
)

# Source -- a slowly-changing state table
crm = StateSource(name="crm_contacts", project="p", dataset="raw", table="contacts", id_field="id")

# Activities -- named business events from state changes
signup = ActivityDefinition(name="signup", source="crm_contacts", trigger=RowAppeared())
became_paying = ActivityDefinition(
    name="became_paying", source="crm_contacts",
    trigger=FieldChanged(field="plan", to_values=["pro", "enterprise"]),
)

# Identity -- resolve across sources
identity = IdentityGraph(
    name="customer_identity", canonical_id="customer_id",
    sources=[IdentitySource(source="crm_contacts", id_field="id", match_key_field="email")],
)

# Entity -- derived current state
customers = EntityModel(
    name="customers", identity_graph="customer_identity",
    state_fields=[
        StateField(name="email", source="crm_contacts", field="email", strategy="latest"),
        StateField(name="plan", source="crm_contacts", field="plan", strategy="latest"),
    ],
)

3. Run tests:

pytest tests/

Core Concepts

Sources

StateSource -- a slowly-changing table (CRM contacts, subscription records). The diff engine automatically detects row appearances, disappearances, and field changes between snapshots.

StateSource(name="crm_contacts", project="p", dataset="d", table="contacts", id_field="contact_id")

EventSource -- an append-only event stream (page views, transactions).

EventSource(
    name="billing_events", project="p", dataset="d", table="transactions",
    entity_id_field="customer_id", timestamp_field="created_at", event_type_field="event_type",
)

Activity Definitions

Named business events detected from raw data changes. Each activity ties to a source and a trigger:

Trigger	Detects
RowAppeared()	New row in a state source
RowDisappeared()	Row removed from a state source
FieldChanged(field, to_values)	Field value changed (optionally to specific values)
EventOccurred(event_types)	Specific event types in an event source

signup = ActivityDefinition(name="signup", source="crm_contacts", trigger=RowAppeared())
became_paying = ActivityDefinition(
    name="became_paying", source="crm_contacts",
    trigger=FieldChanged(field="plan", to_values=["pro", "enterprise"]),
)

Identity Graph

Cross-source identity resolution. Link records from different systems by a shared match key:

IdentityGraph(
    name="customer_identity",
    canonical_id="customer_id",
    sources=[
        IdentitySource(source="crm_contacts", id_field="contact_id", match_key_field="email_hash"),
        IdentitySource(source="billing_events", id_field="customer_id", match_key_field="email_hash"),
    ],
)

Entity Model

Derived current-state projection from resolved identities. Each field picks a source, a column, and a merge strategy (latest, first):

EntityModel(
    name="customers",
    identity_graph="customer_identity",
    state_fields=[
        StateField(name="email", source="crm_contacts", field="email", strategy="latest"),
        StateField(name="first_seen", source="crm_contacts", field="created_at", strategy="first"),
    ],
    computed_fields=[ComputedColumn(name="is_paying", expression="plan != 'free'")],
)

Analytics Model

Time-grain metric aggregation over the activity stream:

StreamAnalyticsModel(
    name="daily_metrics",
    identity_graph="customer_identity",
    date_grain="daily",
    metrics=[
        StreamMetric(name="new_signups", expression="count()", event_filter="signup", metric_type="count"),
        StreamMetric(name="total_customers", expression="count()", metric_type="snapshot"),
    ],
)

CLI

fyr init [project_name]   # Scaffold a new project
fyr --version             # Show version
fyr --help                # Show available commands

Why Fyrnheim?

	dbt	Fyrnheim
Language	SQL + Jinja	Python
Type safety	Runtime errors	Pydantic validation at definition time
Local dev	Requires warehouse connection	DuckDB on local parquet files
Backend portability	Dialect-specific SQL	Ibis compiles to 15+ backends
Testing	Custom schema tests	pytest
Identity resolution	Manual SQL joins	Built-in identity graph

Status

• Alpha -- API may change before 1.0
• DuckDB backend -- fully supported
• BigQuery backend -- supported
• ClickHouse output -- supported as output sink
• Postgres backend -- supported
• Python 3.11+ required

License

MIT