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Django backend for Snowflake

Project description

Snowflake backend for Django

Install and usage

Use the version of django-snowflake that corresponds to your version of Django. For example, to get the latest compatible release for Django 4.2.x:

pip install django-snowflake==4.2.*

The minor release number of Django doesn't correspond to the minor release number of django-snowflake. Use the latest minor release of each.

If a release series of django-snowflake only has pre-releases (alphas or betas), you'll see an error with a list of the available versions. In that case, include --pre to allow pip to install the latest pre-release.

For example, if django-snowflake 4.2 alpha 1 is the latest available version of the 4.2 release series:

$ pip install django-snowflake==4.2.*
ERROR: Could not find a version that satisfies the requirement
django-snowflake==4.2.* (from versions: ..., 4.2a1)

$ pip install --pre django-snowflake==4.2.*
Successfully installed ... django-snowflake-4.2a1 ...

Configure the Django DATABASES setting similar to this:

    'default': {
        'ENGINE': 'django_snowflake',
        'NAME': 'MY_DATABASE',
        'SCHEMA': 'MY_SCHEMA',
        'USER': 'my_user',
        'PASSWORD': 'my_password',
        'ACCOUNT': 'my_account',
        # Include 'OPTIONS' if you need to specify any other
        # snowflake.connector.connect() parameters.
        'OPTIONS': {},

Notes on Django fields

  • Consistent with Snowflake's convention, this backend uppercases all database identifiers (table names, column names, etc.) unless they are quoted, e.g. db_table='"table_name"'.

  • Snowflake supports defining foreign key and unique constraints, however, it doesn't enforce them. Thus, Django manages these constraints and inspectdb detects them, but Django won't raise IntegrityError if they're violated.

  • Snowflake doesn't support indexes. Thus, Django ignores any indexes defined on models or fields.

  • Snowflake doesn't support check constraints, so the various PositiveIntegerField model fields allow negative values (though validation at the form level still works).

Notes on Django QuerySets

  • Snowflake has limited support for subqueries.

  • Valid values for QuerySet.explain()'s format parameter are 'json', 'tabular', and 'text'. The default is 'tabular'.

Known issues and limitations

This list isn't exhaustive. If you run into a problem, consult django_snowflake/ to see if a similar test is skipped. Please create an issue on GitHub if you encounter an issue worth documenting.

  • Snowflake doesn't support last_insert_id to retrieve the ID of a newly created object. Instead, this backend issues the query SELECT MAX(pk_name) FROM table_name to retrieve the ID. This is subject to race conditions if objects are created concurrently. This makes this backend inappropriate for use in web app use cases where multiple clients could be creating objects at the same time. Further, you should not manually specify an ID (e.g. MyModel(id=1)) when creating an object.

  • Snowflake only supports single layer transactions, but Django's TestCase requires that the database supports nested transactions. Therefore, Django's TestCase operates like TransactionTestCase, without the benefit of transactions to speed it up. A future version of Django (5.0 at the earliest) may leverage Snowflake's single layer transactions to give some speed up.

  • Due to snowflake-connector-python's lack of VARIANT support, some JSONField queries with complex JSON parameters don't work.

    For example, if value is a JSONField, this won't work:

    >>> JSONModel.objects.filter(value__k={"l": "m"})

    A workaround is:

    >>> from django.db.models.expressions import RawSQL
    >>> JSONModel.objects.filter(value__k=RawSQL("PARSE_JSON(%s)", ('{"l": "m"}',)))

    In addition, QuerySet.bulk_update() isn't supported for JSONField.

  • Interval math where the interval is a column is not supported.

  • Interval math with a null interval crashes.

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