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dbt for Snowflake Demonstration Project

Dependencies

This project depends on the following two data sets

  • SNOWFLAKE_SAMPLE_DATA that is available by default in all new Snowflake accounts
  • Knoema: Economy Data Atlas
    • It is available for free in the Snowflake Data Markeplace
    • If named other than "KNOEMA_ECONOMY_DATA_ATLAS", update the database name in sources.yml

How to get started

Install Python and Create a Virtual Environment For dbt

  • We generally recommend Anaconda or Miniconda to create an isolated environment just for dbt. A dbt-conda-env.yml file has been provided so you can set up this environment and switch to it with:

    conda env create -f dbt-conda-env.yml
conda activate dbt

  • You can also use venv with the open source version at Python.org

    • Unix/macOS - Setting it up and verifying which python you are now using:

      python3 -m pip install --user virtualenv
python3 -m venv dbt
source dbt/bin/activate
which python
python3 -m pip install -U dbt-core dbt-snowflake

    • Windows - Setting it up and verifying which python you are now using:

      py -m pip install --user virtualenv
py -m venv dbt
.\dbt\Scripts\activate
where python
py -m pip install -U dbt-core dbt-snowflake

Set Up Your Editor

  • Most dbt users edit their dbt scripts with Microsoft's free editor, VSCode
    • Download VSCode
    • From the Extensions screen (icon looks like Tetris) you should install two extensions
    • In the Explorer, right click in the background and "Add folder to workspace" to add where your dbt project will be located.
    • On Windows, you will want to change the default terminal to "Command Prompt". Under File -> Preferences -> Settings, search for "windows terminal" and scroll down to where it says the default is "null" and change that to "Command Prompt".
    • You will want to set the default intepreter to your new "dbt" environment using these instructions from Microsoft.

Set Up Your Snowflake Account

  • Create a target schema in Snowflake that you want to deploy your dbt demo into
  • Add the Knoema Economy Data Atlas and Snowflake Sample Data to your account if necessary

Update Configuration For Your Account and Test Execution

  • Copy the sample profiles.yml file to your ~/.dbt/ folder and update it with your credentials and target DB/schema
  • From the root folder, run dbt deps to download modules from the dbt hub
  • Run dbt build --full-refresh and troubleshoot any errors such as missing objects or permission issues

Cheatsheet of most common dbt commands

  • dbt deps - download 3rd party packages (necessary for this project before build)
  • dbt build - both compile and then run all models & associated tests
  • dbt build --full-refresh - have incremental models run as a full reload
  • dbt build --models modelname - will only compile/run modelname
  • dbt build --models +modelname - will compile/run modelname and all parents
  • dbt build --models modelname+ - will compile/run modelname and all children
  • dbt build --models +modelname+ - will compile/run modelname, and all parents and children
  • dbt build --models @modelname - will compile/run modelname, all parents, all children, AND all parents of all children
  • dbt build --exclude modelname - will compile/run all models except modelname
  • dbt compile - compile all models but do not execute them
  • dbt run - run all models & tests
  • dbt seed - create or refresh small tables from .csv seed files
  • dbt clean - clear your logs and compiled scripts (can fix issues)
  • dbt docs generate - refresh the documentation for your project
  • dbt docs serve - open this documentation in your browser

Additional commands and details are available in dbt's documentation

Project features

  • How to nest models:
    • DIM_ORDERS
    • DIM_CURRENT_YEAR_ORDERS
    • DIM_CURRENT_YEAR_OPEN_ORDERS
  • Snowflake commands in a pre-hook:
    • DIM_CALENDAR_DAY
  • Materializations:
    • LKP_EXCHANGE_RATES (table)
    • LKP_CUSTOMERS_WITH_ORDERS (ephemeral)
    • DIM_CUSTOMERS_SHARE (secure view)
    • FACT_ORDER_LINE (incremental fact)
    • DIM_CUSTOMERS, DIM__CUSTOMERS (incremental dim)
    • DIM_CUSTOMERS_TYPE2 (snapshot)
  • Source data quality tests:
    • sources.yml
  • Model data quality tests:
    • schema.yml
  • Features available in dbt_project.yml
    • run-start/run-end hooks
    • logging before and after modules
    • default materializations by folder path
    • Snowflake features - copy_grants, secure views, warehouse
    • schemas for models
  • Macro examples:
    • snowflake_surrogate_key
    • copy_log_to_snowflake
    • create_masking_policies
  • Jinja expressions:
    • Q1_FACT_PRICING_SUMMARY_REPORT_QUERY
    • Q2_MINIMUM_COST_SUPPLIER_QUERY
    • Q3_SHIPPING_PRIORITY_QUERY
    • Q4_ORDER_PRIORITY_CHECKING_QUERY

Resources