How to configure a Validation Result store to PostgreSQL

By default, Validations are stored in JSON format in the uncommitted/validations/ subdirectory of your great_expectations/ folder. Since Validations may include examples of data (which could be sensitive or regulated) they should not be committed to a source control system. This guide will help you configure Great Expectations to store them in a PostgreSQL database.

Prerequisites: This how-to guide assumes that you have already:

Steps

  1. Configure the config_variables.yml file with your database credentials

    We recommend that database credentials be stored in the config_variables.yml file, which is located in the uncommitted/ folder by default, and is not part of source control. The following lines add database credentials under the key db_creds. Additional options for configuring the config_variables.yml file or additional environment variables can be found here.

    db_creds:
        drivername: postgres
        host: '<your_host_name>'
        port: '<your_port>'
        username: '<your_username>'
        password: '<your_password>'
        database: '<your_database_name>'
    
  2. Identify your Data Context Validations Store

    In your great_expectations.yml, look for the following lines. The configuration tells Great Expectations to look for Validations in a store called validations_store. The base_directory for validations_store is set to uncommitted/validations/ by default.

    validations_store_name: validations_store
    
    stores:
        validations_store:
            class_name: ValidationsStore
            store_backend:
                class_name: TupleFilesystemStoreBackend
                base_directory: uncommitted/validations/
    
  3. Update your configuration file to include a new store for Validations on PostgreSQL

    In our case, the name is set to validations_postgres_store, but it can be any name you like. We also need to make some changes to the store_backend settings. The class_name will be set to DatabaseStoreBackend, and credentials will be set to ${db_creds}, which references the corresponding key in the config_variables.yml file.

    validations_store_name: validations_postgres_store
    
    stores:
        validations_postgres_store:
            class_name: ValidationsStore
            store_backend:
                class_name: DatabaseStoreBackend
                credentials: ${db_creds}
    
  1. Confirm that the new Validations store has been added by running great_expectations store list.

    Notice the output contains two Validation stores: the original validations_store on the local filesystem and the validations_postgres_store we just configured. This is ok, since Great Expectations will look for Validations in PostgreSQL as long as we set the validations_store_name variable to validations_postgres_store. The config for validations_store can be removed if you would like.

    great_expectations store list
    
    - name: validations_store
    class_name: ValidationsStore
    store_backend:
        class_name: TupleFilesystemStoreBackend
        base_directory: uncommitted/validations/
    
    - name: validations_postgres_store
    class_name: ValidationsStore
    store_backend:
        class_name: DatabaseStoreBackend
        credentials:
            database: '<your_db_name>'
            drivername: postgresql
            host: '<your_host_name>'
            password: ******
            port: '<your_port>'
            username: '<your_username>'
    
  2. Confirm that the Validations store has been correctly configured.

    Run a Checkpoint to store results in the new Validations store in PostgreSQL then visualize the results by re-building Data Docs.

    Behind the scenes, Great Expectations will create a new table in your database called ge_validations_store, and populate the fields with information from the Validation results.

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