django-materialized-view 0.1.6.2

Plugin for django to support Materialized Views

Materialized View support for the Django framework. Django (in general) does not support materialized views by the default therefor migrations are not created automatically with ./manage.py makemigrations. This library provides new manage.py command: ./manage.py migrate_with_views. This command is to be used instead of the default one migrate.

This command automatically finds your materialized view models and keeps them up to date. In case when materialized view is a parent view for another materialized view, use migrate_with_views command in order to change query of parent materialized view. migrate_with_views command finds all related materialized views and recreates them sequentially.

Contents

• Requirements
• Installation
• Usage
  • Create class and inherit from MaterializedViewModel
  • Add materialized view query (You can create a materialized view either from Raw SQL or from a queryset)
    • Create materialized view from Raw SQL
    • Create materialized view query from Queryset
  • Use refresh method to update materialized view data

Requirements

django-materialized-view has been tested with:

• Django: 4.0, 4.1
• Python: 3.9, 3.10, 3.11
• Postgres >= 13

Installation

Via pip into a virtualenv:

pip install django-materialized-view

In settings.py add the following:

INSTALLED_APPS = (
    ...
    'django_materialized_view'
)

Before running migrate:

python manage.py migrate

Then you can use new migrate command instead of the default one:

python manage.py migrate_with_views

This command will automatically begin interception of materialized view models, and proceed to create/delete/update your view on your DB if required.

Usage

1. Create class and inherit from MaterializedViewModel

   EXAMPLE:

   from django.db import models
   from django_materialized_view.base_model import MaterializedViewModel
   
   class MyViewModel(MaterializedViewModel):
       create_pkey_index = True  # if you need add unique field as a primary key and create indexes
   
       class Meta:
           managed = False
   
       # if create_pkey_index=True you must add argument primary_key=True
       item = models.OneToOneField("app.ItemModel", on_delete=models.DO_NOTHING, primary_key=True, db_column="id")
       from_seconds = models.IntegerField()
       to_seconds = models.IntegerField()
       type = models.CharField(max_length=255)
   
       # ATTENTION: this method must be a staticmethod or classmethod
       @staticmethod
       def get_query_from_queryset():
           # define this method only in case use queryset as a query for materialized view.
           # Method must return Queryset
           pass
   

2. Add materialized view query (You can create a materialized view either from Raw SQL or from a queryset)

   • Create materialized view from Raw SQL

     1. run django default makemigrations command for creating model migrations if necessary:

        ./manage.py makemigrations
        

     2. run migrate_with_views command for getting your new sql file name and path:

        ./manage.py migrate_with_views
        

     3. you will get file path in your console

        [Errno 2] No such file or directory: '.../app/models/materialized_views/sql_files/myviewmodel.sql' - please create SQL file and put it to this directory
        

     4. create file on suggested path with suggested name
     5. run again django command migrate_with_views:

        ./manage.py migrate_with_views
        

        this command will run the default migrate command and apply materialized views

   • Create materialized view query from Queryset

     1. run django default makemigrations command for creating model migrations if necessary:

        ./manage.py makemigrations
        

     2. add to your materialized view model the method get_query_from_queryset:

        # ATTENTION: this method must be a staticmethod or classmethod
        @staticmethod
         def get_query_from_queryset():
             return SomeModel.objects.all()
        

     3. run django command migrate_with_views:

        ./manage.py migrate_with_views
        

        This command will run default migrate command and apply materialized views

3. Use refresh method to update materialized view data.

   1. For updating concurrently:

      MyViewModel.refresh()
      

   2. For updating non-concurrently:

      MyViewModel.refresh(concurrently=Fasle)
      

   Note: All refreshes will be logged in to the model MaterializedViewRefreshLog:

   class MaterializedViewRefreshLog(models.Model):
       updated_at = models.DateTimeField(auto_now_add=True, db_index=True)
       duration = models.DurationField(null=True)
       failed = models.BooleanField(default=False)
       view_name = models.CharField(max_length=255)
   

Development

• Release CI triggered on tags. To release new version, create the release with new tag on GitHub

• For integration with pytest add following fixture:

  @pytest.fixture(scope="session")
  def django_db_setup(django_db_setup, django_db_blocker):
      with django_db_blocker.unblock():
          view_processor = MaterializedViewsProcessor()
          view_processor.process_materialized_views()