data_check

data_check is a simple data validation tool. In its most basic form it will execute SQL queries and compare the results against CSV or Excel files. But there are more advanced features:

Features

• CSV checks: compare SQL queries against CSV files
• Excel support: Use Excel (xlsx) instead of CSV
• multiple environments (databases) in the configuration file
• populate tables from CSV or Excel files
• execute any SQL files on a database
• more complex pipelines
• run any script/command (via pipelines)
• simplified checks for empty datasets and full table comparison
• lookups to reuse the same data in multiple queries
• test data generation

Database support

data_check is tested with these databases:

• PostgreSQL
• MySQL
• SQLite
• Oracle
• Microsoft SQL Server

Partially supported:

• DuckDB
• Databricks

Other databases supported by SQLAlchemy might also work.

Quickstart

You need Python 3.9 or above to run data_check. The easiest way to install data_check is via pipx:

pipx install data-check

The data_check Git repository is also a sample data_check project. Clone the repository, switch to the folder and run data_check:

git clone git@github.com:andrjas/data_check.git
cd data_check/example
data_check

This will run the tests in the checks folder using the default connection as set in data_check.yml.

See the documentation how to install data_check in different environments with additional database drivers and other usages of data_check.

Project layout

data_check has a simple layout for projects: a single configuration file and a folder with the test files. You can also organize the test files in subfolders.

data_check.yml    # The configuration file
checks/           # Default folder for data tests
    some_test.sql # SQL file with the query to run against the database
    some_test.csv # CSV file with the expected result
    subfolder/    # Tests can be nested in subfolders

CSV checks

This is the default mode when running data_check. data_check expects a SQL file and a CSV file. The SQL file will be executed against the database and the result is compared with the CSV file. If they match, the test is passed, otherwise it fails.

Pipelines

If data_check finds a file named data_check_pipeline.yml in a folder, it will treat this folder as a pipeline check. Instead of running CSV checks it will execute the steps in the YAML file.

Example project with a pipeline:

data_check.yml
checks/
    some_test.sql                # this test will run in parallel to the pipeline test
    some_test.csv
    sample_pipeline/
        data_check_pipeline.yml  # configuration for the pipeline
        data/
            my_schema.some_table.csv       # data for a table
        data2/
            some_data.csv        # other data
        some_checks/             # folder with CSV checks
            check1.sql
            check1.csl
            ...
        run_this.sql             # a SQL file that will be executed
        cleanup.sql
    other_pipeline/              # you can have multiple pipelines that will run in parallel
        data_check_pipeline.yml
        ...

The file sample_pipeline/data_check_pipeline.yml can look like this:

steps:
    # this will truncate the table my_schema.some_table and load it with the data from data/my_schema.some_table.csv
    - load: data
    # this will execute the SQL statement in run_this.sql
    - sql: run_this.sql
    # this will append the data from data2/some_data.csv to my_schema.other_table
    - load:
        file: data2/some_data.csv
        table: my_schema.other_table
        mode: append
    # this will run a python script and pass the connection name
    - cmd: "python3 /path/to/my_pipeline.py --connection {{CONNECTION}}"
    # this will run the CSV checks in the some_checks folder
    - check: some_checks

Pipeline checks and simple CSV checks can coexist in a project.

Documentation

See the documentation how to setup data_check, how to create a new project and more options.

License

MIT