alexBlogs

Don't be dogmatic about following this, you can't get too far off track with this

1. ask questions to understand stakeholder needs

• User story: Dashboard will be visited by this persona at this cadence to make this decision.

1. ask questions to understand data
2. sketch dashboard (on pen and paper)

• chart elements
• define filters

1. SQL queries to generate input to dashboard elements using some_ideal_clean_and_pristine.table_that_you_think_exists
2. Before starting model, do some sensemaking queries on the source data.
3. Start writing the dbt model to product some_ideal_clean_and_pristine.table_that_you_think_exists

• configure sources, test non-null/uniqueness
• Speak to materialization strategy don't add is_incremental until you have a running model?
• create model. Start with import CTEs.
• scaffold with step by step CTEs before you start hacking away.
• filter near the top:
  • deleted records
  • excluded users
  • events too old to be relevant

with events as (
  select * from {{ref('events')}}
  {% if is_incremental() %}
    where event_timestamp >= (select max(event_timestamp)::date from {{this}})
  {% endif %}
)
--rest of model...

{{
    config(
        materialized='incremental',
        unique_key='date_day'
    )
}}

select
    date_trunc('day', event_at) as date_day,
    count(distinct user_id) as daily_active_users

from {{ ref('app_data_events') }}

{% if is_incremental() %}

  -- this filter will only be applied on an incremental run
  -- (uses >= to include records arriving later on the same day as the last run of this model)
  where date_day >= (select coalesce(max(date_day), '1900-01-01') from {{ this }})

{% endif %}

group by 1

dbt run --full-refresh --select my_incremental_model+

I probably want to avoid packages, but if you need codegen or utils, create a packages.yml file in the dir as the project yaml, and run dbt deps.

packages:
  - package: dbt-labs/codegen
    version: 0.10.0

Run dbt deps. And then here's the command line

dbt --quiet run-operation generate_source --args '{"table_names": ["orders"]}' > models/staging/jaffle_shop/_sources.yml

• Late binding views WITH NO SCHEMA BINDING; in dbt it's {{ config(materialized='view', bind=False) }}.
• Auto-refresh

Via the dbt docs for Redshift config

Be up-front about not being super familiar. But my basic understanding is: distkey is for joining, sortkey is for grouping and filtering.

-- Example with one sort key
{{ config(materialized='table', sort='reporting_day', dist='unique_id') }}

select ...


-- Example with multiple sort keys
{{ config(materialized='table', sort=['category', 'region', 'reporting_day'], dist='received_at') }}

select ...


-- Example with interleaved sort keys
{{ config(materialized='table',
          sort_type='interleaved'
          sort=['category', 'region', 'reporting_day'],
          dist='unique_id')
}}

select ...