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Version: 0.16.16

How to configure an Expectation Store to use PostgreSQL

By default, new ProfiledThe act of generating Metrics and candidate Expectations from data. ExpectationsA verifiable assertion about data. are stored as Expectation SuitesA collection of verifiable assertions about data. in JSON format in the expectations/ subdirectory of your great_expectations/ folder. Use the information provided here to configure Great Expectations to store Expectations in a PostgreSQL database.

Prerequisites​

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

GX recommends storing database credentials in the config_variables.yml file, which is located in the uncommitted/ folder by default, and not part of source control.

To add database credentials, open config_variables.yml and add the following entry below the db_creds key: 

    db_creds:
      drivername: postgresql
      host: '<your_host_name>'
      port: '<your_port>'
      username: '<your_username>'
      password: '<your_password>'
      database: '<your_database_name>'

To configure the config_variables.yml file, or additional environment variables, see How to configure credentials.

2. Identify your Data Context Expectations Store​

Open great_expectations.ymland find the following entry: 

expectations_store_name: expectations_store

stores:
  expectations_store:
      class_name: ExpectationsStore
      store_backend:
          class_name: TupleFilesystemStoreBackend
          base_directory: expectations/

This configuration tells Great Expectations to look for Expectations in the expectations_store Store. The default base_directory for expectations_store is expectations/.

3. Update your configuration file to include a new Store for Expectations​

In the following example, expectations_store_name is set to expectations_postgres_store, but it can be personalized. You also need to make some changes to the store_backend settings. The class_name is DatabaseStoreBackend, and credentials is ${db_creds} to reference the corresponding key in the config_variables.yml file. 

expectations_store_name: expectations_postgres_store

stores:
  expectations_postgres_store:
      class_name: ExpectationsStore
      store_backend:
          class_name: DatabaseStoreBackend
          credentials: ${db_creds}