gnomon_dbt | Gnomon Docs

dbt macros for a PostgreSQL database with the gnomon extension.

gnomon_history, a materialization: a model kept in dbt's snapshot shape (dbt_scd_id, dbt_updated_at, dbt_valid_from, dbt_valid_to) from gnomon's change feed. It records every version (a dbt snapshot records the state at each run) and sees hard deletes. The first run loads the history since the table was tracked; later runs apply the changes since, through a feed consumer per model.
```
-- models/customers_history.sql
{{ config(materialized='gnomon_history', source_table='public.customers') }}
select 1
```
gnomon_as_of(ref) and gnomon_on_branch(branch): pre-hooks that read a model's sources at a past moment (a timestamp, tag:<name> or a coordinate) or on a branch, for the model's transaction. A hook is a string dbt renders when the model runs, and a package's macros go by the package's name:
```
{{ config(materialized='table', pre_hook="{{ gnomon_dbt.gnomon_as_of('tag:month_end') }}") }}
select id, name, tier from customers
```
Name the sources without a schema (customers, not {{ source(...) }}'s "public"."customers") unless the server loads gnomon's C module: without it, only unqualified names follow the session's moment or branch.

Install with packages.yml: - git: <this repository> and subdirectory: dbt/gnomon_dbt.

The work happens in SQL, in gnomon.dbt_snapshot(source, target): test/sql/21_dbt.sql checks that the rows valid at every tick equal the as-of read there. test/shell/dbt.sh runs the package through dbt itself (integration_tests/): a gnomon_history model's first run, a later run and a run with nothing new, and models with each pre-hook, compared with gnomon's own reads.