django-aggtrigg

Create triggers to do some aggregate and permit to count objects from database without using COUNT() aggregat.

Detailed documentation is in the “docs” directory.

Quick start

1. Add “django_aggtrigg” to your INSTALLED_APPS setting like this:

   INSTALLED_APPS = (
       ...
       'django_aggtrigg',
   )
   

2. Import fields in your models:

   from django_aggtrigg.models import IntegerTriggerField
   from django_aggtrigg.models import FloatTriggerField
   

3. Configure your fields as is:

   class Apple(models.Model):
       indice = IntegerTriggerField(default=0)
       indice.aggregate_trigger=['count','min']
   
       mark = FloatTriggerField(default=0)
       mark.aggregate_trigger=['min']
   

By default only the count aggregat will be created.

4. Use the new manager on you Model

   objects = AggTriggManager()

Manage triggers and related objects

To create the triggers in the database do:

python manage.py aggtrigg_create

Dropping triggers is easy as doing:

python manage.py aggtrigg_drop | psql -d DATABASE NAME

For safety reason the drop command just ouptput on stdout the SQL statements.

To initialize the aggregeate table, you can fill it by hand or do:

python manage.py aggtrigg_initialize

Howto use the new aggregat

Instead of doing a COUNT as the traditionnal way:

Apple.objects.filter(indice=42).count()

you will do:

Apple.objects.optimized_count(indice=42)

This is may be less easy, but so much more efficient when you manipulate billions or tuples in your relations.

What inside

The class apple was create in the app called foo so the default name of the table that contains data will be foo_apple, we use the tablename from the Model so if it’s changed in Meta will still be compliant.

A new table foo_apple__indice_agg is created in the same database as foo_apple, it will contain the aggregat:

foo=# \d foo_apple__indice_agg
Table "public.foo_apple__indice_agg"
  Column   |  Type   | Modifiers
-----------+---------+-----------
 indice    | integer |
 agg_count | integer |
 agg_min   | integer |
Indexes:
    "foo_apple__indice_agg_indice_idx" btree (indice)

Contents

• Install
• About django-aggtrigg
  • Vision
  • License
  • Authors & contributors
  • Changelog
• Contributing

Indices and tables

• Index
• Module Index
• Search Page