db

Question 1

The way select_related works is it

Answer 1

creates a join on the foreign key columns so you return all the data together in one query. (Imagine it nested)

select_related only works on single value fields: foreign key and one to one.

Question 2

Using select_related and prefetch related does not

Answer 2

change how you access the foreign fields.

Question 3

To use prefetch_related on a reverse foreign key relationship, type

Answer 3

ModelName.objects.all().prefetch_related(‘model_name_set’)

Question 4

The way prefetch_related works is it

Answer 4

does a separate lookup for each relationship, and does the ‘joining’ in python.

Question 5

To log queries to the console, use

Answer 5

pip install django-queryinspect

MIDDLEWARE = [
‘qinspect.middleware.QueryInspectMiddleware’,

QUERY_INSPECT_ENABLED = True

LOGGING = {
    'version': 1,
    'handlers': {
        'console': {
            'level': 'DEBUG',
            'class': 'logging.StreamHandler',
        },
    },
    'loggers': {
        'qinspect': {
            'handlers': ['console'],
            'level': 'DEBUG',
            'propagate': True,
        },
    },
}