Issue with basic django admin and "LogEntry"

[pakal]

Accessing the Django2.2.1 admin on a rather simple project, with nplusone 1.0.0, raises this error :

"Potential unnecessary eager load detected on LogEntry.user"

I don't get what this means, since LogEntry.user is a ForeignKey, how could it lead to a heavy loading ? What kind of problem does nplusone report in this case, is it with the User model or with the LogEntry model ?

[pakal]

Django debug toolbar reports that only 1 sql query is issue on /admin/ page, the one below.
But this query IS used, there is a list of recent user actions in the HTML response. Could it be a "false positive"?

SELECT ••• FROM "django_admin_log" INNER JOIN "accounts_user" ON ("django_admin_log"."user_id" = "accounts_user"."id") LEFT OUTER JOIN "django_content_type" ON ("django_admin_log"."content_type_id" = "django_content_type"."id") WHERE "django_admin_log"."user_id" = '1' ORDER BY "django_admin_log"."action_time" DESC LIMIT 10

[hartwork]

There are two typoes of anomalies that nplusone reports about:

• a) N+1 that should be prevented
• b) N+1 protection costs that do not pair with an actual N+1 problem.

The query above contains two joins. If at least one of these is the result of use of select_related, warning "unnecessary eager load" is justified if some of the joined-in data turns out unused. That would be case (b).

My impression right now: Not a bug in nplusone but suboptimally performing code in Django admin. What do you think?

[erdseb]

This workaround did the trick for me:

NPLUSONE_WHITELIST = [
    {'model': 'admin.LogEntry', 'label': 'unused_eager_load'},
]

[pakal]

Allright I'll check the next time that it appears somewhere - i'm not on this project anymore ; maybe it issued a select_related() on User and never used it, indeeed.