أداء الاستعلام والقياس

from django.conf import settings
settings.configure(
    SECRET_KEY="synthetic-course-key",
    USE_I18N=False, USE_TZ=True,
    INSTALLED_APPS=[],
    DATABASES={"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}},
    DEFAULT_AUTO_FIELD="django.db.models.AutoField",
    ALLOWED_HOSTS=["testserver"],
)
import django
django.setup()

from django.db import connection, models
from django.test.utils import CaptureQueriesContext

class Instructor(models.Model):
    name = models.CharField(max_length=60)
    class Meta:
        app_label = "lab"

class Course(models.Model):
    instructor = models.ForeignKey(Instructor, on_delete=models.PROTECT)
    class Meta:
        app_label = "lab"

with connection.schema_editor() as editor:
    editor.create_model(Instructor)
    editor.create_model(Course)
owner = Instructor.objects.create(name="Mira")
Course.objects.create(instructor=owner)
Course.objects.create(instructor=owner)
with CaptureQueriesContext(connection) as queries:
    names = [row.instructor.name for row in Course.objects.select_related("instructor").order_by("pk")]
print(names)
print(len(queries))

['Mira', 'Mira']
1

تقاس القراءة فقط دون الإعداد وبقاعدة ذاكرية مؤقتة.

from django.conf import settings
settings.configure(
    SECRET_KEY="synthetic-course-key",
    USE_I18N=False, USE_TZ=True,
    INSTALLED_APPS=[],
    DATABASES={"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}},
    DEFAULT_AUTO_FIELD="django.db.models.AutoField",
    ALLOWED_HOSTS=["testserver"],
)
import django
django.setup()

from django.db import connection, models
from django.db.models import Count

class Course(models.Model):
    category = models.CharField(max_length=30)
    class Meta:
        app_label = "lab"

with connection.schema_editor() as editor:
    editor.create_model(Course)
Course.objects.bulk_create([Course(category="web"), Course(category="web"), Course(category="data")])
rows = Course.objects.values("category").annotate(total=Count("pk")).order_by("category")
print([(row["category"], row["total"]) for row in rows])

[('data', 1), ('web', 2)]

التجميع بالفئة وعد واحد للمجموعة وفي العينة بيانات واحدة وويب اثنتان.